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Chapter 20. OVN-Kubernetes network plugin
20.1. About the OVN-Kubernetes network plugin
The OpenShift Container Platform cluster uses a virtualized network for pod and service networks.
Part of Red Hat OpenShift Networking, the OVN-Kubernetes network plugin is the default network provider for OpenShift Container Platform. OVN-Kubernetes is based on Open Virtual Network (OVN) and provides an overlay-based networking implementation. A cluster that uses the OVN-Kubernetes plugin also runs Open vSwitch (OVS) on each node. OVN configures OVS on each node to implement the declared network configuration.
OVN-Kubernetes is the default networking solution for OpenShift Container Platform and single-node OpenShift deployments.
OVN-Kubernetes, which arose from the OVS project, uses many of the same constructs, such as open flow rules, to determine how packets travel through the network. For more information, see the Open Virtual Network website.
OVN-Kubernetes is a series of daemons for OVS that translate virtual network configurations into OpenFlow
rules. OpenFlow
is a protocol for communicating with network switches and routers, providing a means for remotely controlling the flow of network traffic on a network device so that network administrators can configure, manage, and monitor the flow of network traffic.
OVN-Kubernetes provides more of the advanced functionality not available with OpenFlow
. OVN supports distributed virtual routing, distributed logical switches, access control, Dynamic Host Configuration Protocol (DHCP), and DNS. OVN implements distributed virtual routing within logic flows that equate to open flows. For example, if you have a pod that sends out a DHCP request to the DHCP server on the network, a logic flow rule in the request helps the OVN-Kubernetes handle the packet so that the server can respond with gateway, DNS server, IP address, and other information.
OVN-Kubernetes runs a daemon on each node. There are daemon sets for the databases and for the OVN controller that run on every node. The OVN controller programs the Open vSwitch daemon on the nodes to support the network provider features: egress IPs, firewalls, routers, hybrid networking, IPSEC encryption, IPv6, network policy, network policy logs, hardware offloading, and multicast.
20.1.1. OVN-Kubernetes purpose
The OVN-Kubernetes network plugin is an open-source, fully-featured Kubernetes CNI plugin that uses Open Virtual Network (OVN) to manage network traffic flows. OVN is a community developed, vendor-agnostic network virtualization solution. The OVN-Kubernetes network plugin uses the following technologies:
- OVN to manage network traffic flows.
- Kubernetes network policy support and logs, including ingress and egress rules.
- The Generic Network Virtualization Encapsulation (Geneve) protocol, rather than Virtual Extensible LAN (VXLAN), to create an overlay network between nodes.
The OVN-Kubernetes network plugin supports the following capabilities:
- Hybrid clusters that can run both Linux and Microsoft Windows workloads. This environment is known as hybrid networking.
- Offloading of network data processing from the host central processing unit (CPU) to compatible network cards and data processing units (DPUs). This is known as hardware offloading.
- IPv4-primary dual-stack networking on bare-metal, VMware vSphere, IBM Power®, IBM Z®, and RHOSP platforms.
- IPv6 single-stack networking on a bare-metal platform.
- IPv6-primary dual-stack networking for a cluster running on a bare-metal, a VMware vSphere, or an RHOSP platform.
- Egress firewall devices and egress IP addresses.
- Egress router devices that operate in redirect mode.
- IPsec encryption of intracluster communications.
20.1.2. OVN-Kubernetes IPv6 and dual-stack limitations
The OVN-Kubernetes network plugin has the following limitations:
For clusters configured for dual-stack networking, both IPv4 and IPv6 traffic must use the same network interface as the default gateway. If this requirement is not met, pods on the host in the
ovnkube-node
daemon set enter theCrashLoopBackOff
state. If you display a pod with a command such asoc get pod -n openshift-ovn-kubernetes -l app=ovnkube-node -o yaml
, thestatus
field contains more than one message about the default gateway, as shown in the following output:I1006 16:09:50.985852 60651 helper_linux.go:73] Found default gateway interface br-ex 192.168.127.1 I1006 16:09:50.985923 60651 helper_linux.go:73] Found default gateway interface ens4 fe80::5054:ff:febe:bcd4 F1006 16:09:50.985939 60651 ovnkube.go:130] multiple gateway interfaces detected: br-ex ens4
The only resolution is to reconfigure the host networking so that both IP families use the same network interface for the default gateway.
For clusters configured for dual-stack networking, both the IPv4 and IPv6 routing tables must contain the default gateway. If this requirement is not met, pods on the host in the
ovnkube-node
daemon set enter theCrashLoopBackOff
state. If you display a pod with a command such asoc get pod -n openshift-ovn-kubernetes -l app=ovnkube-node -o yaml
, thestatus
field contains more than one message about the default gateway, as shown in the following output:I0512 19:07:17.589083 108432 helper_linux.go:74] Found default gateway interface br-ex 192.168.123.1 F0512 19:07:17.589141 108432 ovnkube.go:133] failed to get default gateway interface
The only resolution is to reconfigure the host networking so that both IP families contain the default gateway.
20.1.3. Session affinity
Session affinity is a feature that applies to Kubernetes Service
objects. You can use session affinity if you want to ensure that each time you connect to a <service_VIP>:<Port>, the traffic is always load balanced to the same back end. For more information, including how to set session affinity based on a client’s IP address, see Session affinity.
Stickiness timeout for session affinity
The OVN-Kubernetes network plugin for OpenShift Container Platform calculates the stickiness timeout for a session from a client based on the last packet. For example, if you run a curl
command 10 times, the sticky session timer starts from the tenth packet not the first. As a result, if the client is continuously contacting the service, then the session never times out. The timeout starts when the service has not received a packet for the amount of time set by the timeoutSeconds
parameter.
20.2. OVN-Kubernetes architecture
20.2.1. Introduction to OVN-Kubernetes architecture
The following diagram shows the OVN-Kubernetes architecture.
Figure 20.1. OVK-Kubernetes architecture
The key components are:
- Cloud Management System (CMS) - A platform specific client for OVN that provides a CMS specific plugin for OVN integration. The plugin translates the cloud management system’s concept of the logical network configuration, stored in the CMS configuration database in a CMS-specific format, into an intermediate representation understood by OVN.
-
OVN Northbound database (
nbdb
) container - Stores the logical network configuration passed by the CMS plugin. -
OVN Southbound database (
sbdb
) container - Stores the physical and logical network configuration state for Open vSwitch (OVS) system on each node, including tables that bind them. -
OVN north daemon (
ovn-northd
) - This is the intermediary client betweennbdb
container andsbdb
container. It translates the logical network configuration in terms of conventional network concepts, taken from thenbdb
container, into logical data path flows in thesbdb
container. The container name forovn-northd
daemon isnorthd
and it runs in theovnkube-node
pods. -
ovn-controller - This is the OVN agent that interacts with OVS and hypervisors, for any information or update that is needed for
sbdb
container. Theovn-controller
reads logical flows from thesbdb
container, translates them intoOpenFlow
flows and sends them to the node’s OVS daemon. The container name isovn-controller
and it runs in theovnkube-node
pods.
The OVN northd, northbound database, and southbound database run on each node in the cluster and mostly contain and process information that is local to that node.
The OVN northbound database has the logical network configuration passed down to it by the cloud management system (CMS). The OVN northbound database contains the current desired state of the network, presented as a collection of logical ports, logical switches, logical routers, and more. The ovn-northd
(northd
container) connects to the OVN northbound database and the OVN southbound database. It translates the logical network configuration in terms of conventional network concepts, taken from the OVN northbound database, into logical data path flows in the OVN southbound database.
The OVN southbound database has physical and logical representations of the network and binding tables that link them together. It contains the chassis information of the node and other constructs like remote transit switch ports that are required to connect to the other nodes in the cluster. The OVN southbound database also contains all the logic flows. The logic flows are shared with the ovn-controller
process that runs on each node and the ovn-controller
turns those into OpenFlow
rules to program Open vSwitch
(OVS).
The Kubernetes control plane nodes contain two ovnkube-control-plane
pods on separate nodes, which perform the central IP address management (IPAM) allocation for each node in the cluster. At any given time, a single ovnkube-control-plane
pod is the leader.
20.2.2. Listing all resources in the OVN-Kubernetes project
Finding the resources and containers that run in the OVN-Kubernetes project is important to help you understand the OVN-Kubernetes networking implementation.
Prerequisites
-
Access to the cluster as a user with the
cluster-admin
role. -
The OpenShift CLI (
oc
) installed.
Procedure
Run the following command to get all resources, endpoints, and
ConfigMaps
in the OVN-Kubernetes project:$ oc get all,ep,cm -n openshift-ovn-kubernetes
Example output
Warning: apps.openshift.io/v1 DeploymentConfig is deprecated in v4.14+, unavailable in v4.10000+ NAME READY STATUS RESTARTS AGE pod/ovnkube-control-plane-65c6f55656-6d55h 2/2 Running 0 114m pod/ovnkube-control-plane-65c6f55656-fd7vw 2/2 Running 2 (104m ago) 114m pod/ovnkube-node-bcvts 8/8 Running 0 113m pod/ovnkube-node-drgvv 8/8 Running 0 113m pod/ovnkube-node-f2pxt 8/8 Running 0 113m pod/ovnkube-node-frqsb 8/8 Running 0 105m pod/ovnkube-node-lbxkk 8/8 Running 0 105m pod/ovnkube-node-tt7bx 8/8 Running 1 (102m ago) 105m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/ovn-kubernetes-control-plane ClusterIP None <none> 9108/TCP 114m service/ovn-kubernetes-node ClusterIP None <none> 9103/TCP,9105/TCP 114m NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE daemonset.apps/ovnkube-node 6 6 6 6 6 beta.kubernetes.io/os=linux 114m NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/ovnkube-control-plane 3/3 3 3 114m NAME DESIRED CURRENT READY AGE replicaset.apps/ovnkube-control-plane-65c6f55656 3 3 3 114m NAME ENDPOINTS AGE endpoints/ovn-kubernetes-control-plane 10.0.0.3:9108,10.0.0.4:9108,10.0.0.5:9108 114m endpoints/ovn-kubernetes-node 10.0.0.3:9105,10.0.0.4:9105,10.0.0.5:9105 + 9 more... 114m NAME DATA AGE configmap/control-plane-status 1 113m configmap/kube-root-ca.crt 1 114m configmap/openshift-service-ca.crt 1 114m configmap/ovn-ca 1 114m configmap/ovnkube-config 1 114m configmap/signer-ca 1 114m
There is one
ovnkube-node
pod for each node in the cluster. Theovnkube-config
config map has the OpenShift Container Platform OVN-Kubernetes configurations.List all of the containers in the
ovnkube-node
pods by running the following command:$ oc get pods ovnkube-node-bcvts -o jsonpath='{.spec.containers[*].name}' -n openshift-ovn-kubernetes
Expected output
ovn-controller ovn-acl-logging kube-rbac-proxy-node kube-rbac-proxy-ovn-metrics northd nbdb sbdb ovnkube-controller
The
ovnkube-node
pod is made up of several containers. It is responsible for hosting the northbound database (nbdb
container), the southbound database (sbdb
container), the north daemon (northd
container),ovn-controller
and theovnkube-controller
container. Theovnkube-controller
container watches for API objects like pods, egress IPs, namespaces, services, endpoints, egress firewall, and network policies. It is also responsible for allocating pod IP from the available subnet pool for that node.List all the containers in the
ovnkube-control-plane
pods by running the following command:$ oc get pods ovnkube-control-plane-65c6f55656-6d55h -o jsonpath='{.spec.containers[*].name}' -n openshift-ovn-kubernetes
Expected output
kube-rbac-proxy ovnkube-cluster-manager
The
ovnkube-control-plane
pod has a container (ovnkube-cluster-manager
) that resides on each OpenShift Container Platform node. Theovnkube-cluster-manager
container allocates pod subnet, transit switch subnet IP and join switch subnet IP to each node in the cluster. Thekube-rbac-proxy
container monitors metrics for theovnkube-cluster-manager
container.
20.2.3. Listing the OVN-Kubernetes northbound database contents
Each node is controlled by the ovnkube-controller
container running in the ovnkube-node
pod on that node. To understand the OVN logical networking entities you need to examine the northbound database that is running as a container inside the ovnkube-node
pod on that node to see what objects are in the node you wish to see.
Prerequisites
-
Access to the cluster as a user with the
cluster-admin
role. -
The OpenShift CLI (
oc
) installed.
To run ovn nbctl
or sbctl
commands in a cluster you must open a remote shell into the nbdb
or sbdb
containers on the relevant node
List pods by running the following command:
$ oc get po -n openshift-ovn-kubernetes
Example output
NAME READY STATUS RESTARTS AGE ovnkube-control-plane-8444dff7f9-4lh9k 2/2 Running 0 27m ovnkube-control-plane-8444dff7f9-5rjh9 2/2 Running 0 27m ovnkube-node-55xs2 8/8 Running 0 26m ovnkube-node-7r84r 8/8 Running 0 16m ovnkube-node-bqq8p 8/8 Running 0 17m ovnkube-node-mkj4f 8/8 Running 0 26m ovnkube-node-mlr8k 8/8 Running 0 26m ovnkube-node-wqn2m 8/8 Running 0 16m
Optional: To list the pods with node information, run the following command:
$ oc get pods -n openshift-ovn-kubernetes -owide
Example output
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ovnkube-control-plane-8444dff7f9-4lh9k 2/2 Running 0 27m 10.0.0.3 ci-ln-t487nnb-72292-mdcnq-master-1 <none> <none> ovnkube-control-plane-8444dff7f9-5rjh9 2/2 Running 0 27m 10.0.0.4 ci-ln-t487nnb-72292-mdcnq-master-2 <none> <none> ovnkube-node-55xs2 8/8 Running 0 26m 10.0.0.4 ci-ln-t487nnb-72292-mdcnq-master-2 <none> <none> ovnkube-node-7r84r 8/8 Running 0 17m 10.0.128.3 ci-ln-t487nnb-72292-mdcnq-worker-b-wbz7z <none> <none> ovnkube-node-bqq8p 8/8 Running 0 17m 10.0.128.2 ci-ln-t487nnb-72292-mdcnq-worker-a-lh7ms <none> <none> ovnkube-node-mkj4f 8/8 Running 0 27m 10.0.0.5 ci-ln-t487nnb-72292-mdcnq-master-0 <none> <none> ovnkube-node-mlr8k 8/8 Running 0 27m 10.0.0.3 ci-ln-t487nnb-72292-mdcnq-master-1 <none> <none> ovnkube-node-wqn2m 8/8 Running 0 17m 10.0.128.4 ci-ln-t487nnb-72292-mdcnq-worker-c-przlm <none> <none>
Navigate into a pod to look at the northbound database by running the following command:
$ oc rsh -c nbdb -n openshift-ovn-kubernetes ovnkube-node-55xs2
Run the following command to show all the objects in the northbound database:
$ ovn-nbctl show
The output is too long to list here. The list includes the NAT rules, logical switches, load balancers and so on.
You can narrow down and focus on specific components by using some of the following optional commands:
Run the following command to show the list of logical routers:
$ oc exec -n openshift-ovn-kubernetes -it ovnkube-node-55xs2 \ -c northd -- ovn-nbctl lr-list
Example output
45339f4f-7d0b-41d0-b5f9-9fca9ce40ce6 (GR_ci-ln-t487nnb-72292-mdcnq-master-2) 96a0a0f0-e7ed-4fec-8393-3195563de1b8 (ovn_cluster_router)
NoteFrom this output you can see there is router on each node plus an
ovn_cluster_router
.Run the following command to show the list of logical switches:
$ oc exec -n openshift-ovn-kubernetes -it ovnkube-node-55xs2 \ -c nbdb -- ovn-nbctl ls-list
Example output
bdd7dc3d-d848-4a74-b293-cc15128ea614 (ci-ln-t487nnb-72292-mdcnq-master-2) b349292d-ee03-4914-935f-1940b6cb91e5 (ext_ci-ln-t487nnb-72292-mdcnq-master-2) 0aac0754-ea32-4e33-b086-35eeabf0a140 (join) 992509d7-2c3f-4432-88db-c179e43592e5 (transit_switch)
NoteFrom this output you can see there is an ext switch for each node plus switches with the node name itself and a join switch.
Run the following command to show the list of load balancers:
$ oc exec -n openshift-ovn-kubernetes -it ovnkube-node-55xs2 \ -c nbdb -- ovn-nbctl lb-list
Example output
UUID LB PROTO VIP IPs 7c84c673-ed2a-4436-9a1f-9bc5dd181eea Service_default/ tcp 172.30.0.1:443 10.0.0.3:6443,169.254.169.2:6443,10.0.0.5:6443 4d663fd9-ddc8-4271-b333-4c0e279e20bb Service_default/ tcp 172.30.0.1:443 10.0.0.3:6443,10.0.0.4:6443,10.0.0.5:6443 292eb07f-b82f-4962-868a-4f541d250bca Service_openshif tcp 172.30.105.247:443 10.129.0.12:8443 034b5a7f-bb6a-45e9-8e6d-573a82dc5ee3 Service_openshif tcp 172.30.192.38:443 10.0.0.3:10259,10.0.0.4:10259,10.0.0.5:10259 a68bb53e-be84-48df-bd38-bdd82fcd4026 Service_openshif tcp 172.30.161.125:8443 10.129.0.32:8443 6cc21b3d-2c54-4c94-8ff5-d8e017269c2e Service_openshif tcp 172.30.3.144:443 10.129.0.22:8443 37996ffd-7268-4862-a27f-61cd62e09c32 Service_openshif tcp 172.30.181.107:443 10.129.0.18:8443 81d4da3c-f811-411f-ae0c-bc6713d0861d Service_openshif tcp 172.30.228.23:443 10.129.0.29:8443 ac5a4f3b-b6ba-4ceb-82d0-d84f2c41306e Service_openshif tcp 172.30.14.240:9443 10.129.0.36:9443 c88979fb-1ef5-414b-90ac-43b579351ac9 Service_openshif tcp 172.30.231.192:9001 10.128.0.5:9001,10.128.2.5:9001,10.129.0.5:9001,10.129.2.4:9001,10.130.0.3:9001,10.131.0.3:9001 fcb0a3fb-4a77-4230-a84a-be45dce757e8 Service_openshif tcp 172.30.189.92:443 10.130.0.17:8440 67ef3e7b-ceb9-4bf0-8d96-b43bde4c9151 Service_openshif tcp 172.30.67.218:443 10.129.0.9:8443 d0032fba-7d5e-424a-af25-4ab9b5d46e81 Service_openshif tcp 172.30.102.137:2379 10.0.0.3:2379,10.0.0.4:2379,10.0.0.5:2379 tcp 172.30.102.137:9979 10.0.0.3:9979,10.0.0.4:9979,10.0.0.5:9979 7361c537-3eec-4e6c-bc0c-0522d182abd4 Service_openshif tcp 172.30.198.215:9001 10.0.0.3:9001,10.0.0.4:9001,10.0.0.5:9001,10.0.128.2:9001,10.0.128.3:9001,10.0.128.4:9001 0296c437-1259-410b-a6fd-81c310ad0af5 Service_openshif tcp 172.30.198.215:9001 10.0.0.3:9001,169.254.169.2:9001,10.0.0.5:9001,10.0.128.2:9001,10.0.128.3:9001,10.0.128.4:9001 5d5679f5-45b8-479d-9f7c-08b123c688b8 Service_openshif tcp 172.30.38.253:17698 10.128.0.52:17698,10.129.0.84:17698,10.130.0.60:17698 2adcbab4-d1c9-447d-9573-b5dc9f2efbfa Service_openshif tcp 172.30.148.52:443 10.0.0.4:9202,10.0.0.5:9202 tcp 172.30.148.52:444 10.0.0.4:9203,10.0.0.5:9203 tcp 172.30.148.52:445 10.0.0.4:9204,10.0.0.5:9204 tcp 172.30.148.52:446 10.0.0.4:9205,10.0.0.5:9205 2a33a6d7-af1b-4892-87cc-326a380b809b Service_openshif tcp 172.30.67.219:9091 10.129.2.16:9091,10.131.0.16:9091 tcp 172.30.67.219:9092 10.129.2.16:9092,10.131.0.16:9092 tcp 172.30.67.219:9093 10.129.2.16:9093,10.131.0.16:9093 tcp 172.30.67.219:9094 10.129.2.16:9094,10.131.0.16:9094 f56f59d7-231a-4974-99b3-792e2741ec8d Service_openshif tcp 172.30.89.212:443 10.128.0.41:8443,10.129.0.68:8443,10.130.0.44:8443 08c2c6d7-d217-4b96-b5d8-c80c4e258116 Service_openshif tcp 172.30.102.137:2379 10.0.0.3:2379,169.254.169.2:2379,10.0.0.5:2379 tcp 172.30.102.137:9979 10.0.0.3:9979,169.254.169.2:9979,10.0.0.5:9979 60a69c56-fc6a-4de6-bd88-3f2af5ba5665 Service_openshif tcp 172.30.10.193:443 10.129.0.25:8443 ab1ef694-0826-4671-a22c-565fc2d282ec Service_openshif tcp 172.30.196.123:443 10.128.0.33:8443,10.129.0.64:8443,10.130.0.37:8443 b1fb34d3-0944-4770-9ee3-2683e7a630e2 Service_openshif tcp 172.30.158.93:8443 10.129.0.13:8443 95811c11-56e2-4877-be1e-c78ccb3a82a9 Service_openshif tcp 172.30.46.85:9001 10.130.0.16:9001 4baba1d1-b873-4535-884c-3f6fc07a50fd Service_openshif tcp 172.30.28.87:443 10.129.0.26:8443 6c2e1c90-f0ca-484e-8a8e-40e71442110a Service_openshif udp 172.30.0.10:53 10.128.0.13:5353,10.128.2.6:5353,10.129.0.39:5353,10.129.2.6:5353,10.130.0.11:5353,10.131.0.9:5353
NoteFrom this truncated output you can see there are many OVN-Kubernetes load balancers. Load balancers in OVN-Kubernetes are representations of services.
Run the following command to display the options available with the command
ovn-nbctl
:$ oc exec -n openshift-ovn-kubernetes -it ovnkube-node-55xs2 \ -c nbdb ovn-nbctl --help
20.2.4. Command line arguments for ovn-nbctl to examine northbound database contents
The following table describes the command line arguments that can be used with ovn-nbctl
to examine the contents of the northbound database.
Open a remote shell in the pod you want to view the contents of and then run the ovn-nbctl
commands.
Argument | Description |
---|---|
| An overview of the northbound database contents as seen from a specific node. |
| Show the details associated with the specified switch or router. |
| Show the logical routers. |
|
Using the router information from |
| Show network address translation details for the specified router. |
| Show the logical switches |
|
Using the switch information from |
| Get the type for the logical port. |
| Show the load balancers. |
20.2.5. Listing the OVN-Kubernetes southbound database contents
Each node is controlled by the ovnkube-controller
container running in the ovnkube-node
pod on that node. To understand the OVN logical networking entities you need to examine the northbound database that is running as a container inside the ovnkube-node
pod on that node to see what objects are in the node you wish to see.
Prerequisites
-
Access to the cluster as a user with the
cluster-admin
role. -
The OpenShift CLI (
oc
) installed.
To run ovn nbctl
or sbctl
commands in a cluster you must open a remote shell into the nbdb
or sbdb
containers on the relevant node
List the pods by running the following command:
$ oc get po -n openshift-ovn-kubernetes
Example output
NAME READY STATUS RESTARTS AGE ovnkube-control-plane-8444dff7f9-4lh9k 2/2 Running 0 27m ovnkube-control-plane-8444dff7f9-5rjh9 2/2 Running 0 27m ovnkube-node-55xs2 8/8 Running 0 26m ovnkube-node-7r84r 8/8 Running 0 16m ovnkube-node-bqq8p 8/8 Running 0 17m ovnkube-node-mkj4f 8/8 Running 0 26m ovnkube-node-mlr8k 8/8 Running 0 26m ovnkube-node-wqn2m 8/8 Running 0 16m
Optional: To list the pods with node information, run the following command:
$ oc get pods -n openshift-ovn-kubernetes -owide
Example output
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ovnkube-control-plane-8444dff7f9-4lh9k 2/2 Running 0 27m 10.0.0.3 ci-ln-t487nnb-72292-mdcnq-master-1 <none> <none> ovnkube-control-plane-8444dff7f9-5rjh9 2/2 Running 0 27m 10.0.0.4 ci-ln-t487nnb-72292-mdcnq-master-2 <none> <none> ovnkube-node-55xs2 8/8 Running 0 26m 10.0.0.4 ci-ln-t487nnb-72292-mdcnq-master-2 <none> <none> ovnkube-node-7r84r 8/8 Running 0 17m 10.0.128.3 ci-ln-t487nnb-72292-mdcnq-worker-b-wbz7z <none> <none> ovnkube-node-bqq8p 8/8 Running 0 17m 10.0.128.2 ci-ln-t487nnb-72292-mdcnq-worker-a-lh7ms <none> <none> ovnkube-node-mkj4f 8/8 Running 0 27m 10.0.0.5 ci-ln-t487nnb-72292-mdcnq-master-0 <none> <none> ovnkube-node-mlr8k 8/8 Running 0 27m 10.0.0.3 ci-ln-t487nnb-72292-mdcnq-master-1 <none> <none> ovnkube-node-wqn2m 8/8 Running 0 17m 10.0.128.4 ci-ln-t487nnb-72292-mdcnq-worker-c-przlm <none> <none>
Navigate into a pod to look at the southbound database:
$ oc rsh -c sbdb -n openshift-ovn-kubernetes ovnkube-node-55xs2
Run the following command to show all the objects in the southbound database:
$ ovn-sbctl show
Example output
Chassis "5db31703-35e9-413b-8cdf-69e7eecb41f7" hostname: ci-ln-9gp362t-72292-v2p94-worker-a-8bmwz Encap geneve ip: "10.0.128.4" options: {csum="true"} Port_Binding tstor-ci-ln-9gp362t-72292-v2p94-worker-a-8bmwz Chassis "070debed-99b7-4bce-b17d-17e720b7f8bc" hostname: ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Encap geneve ip: "10.0.128.2" options: {csum="true"} Port_Binding k8s-ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding rtoe-GR_ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding openshift-monitoring_alertmanager-main-1 Port_Binding rtoj-GR_ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding etor-GR_ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding cr-rtos-ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding openshift-e2e-loki_loki-promtail-qcrcz Port_Binding jtor-GR_ci-ln-9gp362t-72292-v2p94-worker-b-svmp6 Port_Binding openshift-multus_network-metrics-daemon-mkd4t Port_Binding openshift-ingress-canary_ingress-canary-xtvj4 Port_Binding openshift-ingress_router-default-6c76cbc498-pvlqk Port_Binding openshift-dns_dns-default-zz582 Port_Binding openshift-monitoring_thanos-querier-57585899f5-lbf4f Port_Binding openshift-network-diagnostics_network-check-target-tn228 Port_Binding openshift-monitoring_prometheus-k8s-0 Port_Binding openshift-image-registry_image-registry-68899bd877-xqxjj Chassis "179ba069-0af1-401c-b044-e5ba90f60fea" hostname: ci-ln-9gp362t-72292-v2p94-master-0 Encap geneve ip: "10.0.0.5" options: {csum="true"} Port_Binding tstor-ci-ln-9gp362t-72292-v2p94-master-0 Chassis "68c954f2-5a76-47be-9e84-1cb13bd9dab9" hostname: ci-ln-9gp362t-72292-v2p94-worker-c-mjf9w Encap geneve ip: "10.0.128.3" options: {csum="true"} Port_Binding tstor-ci-ln-9gp362t-72292-v2p94-worker-c-mjf9w Chassis "2de65d9e-9abf-4b6e-a51d-a1e038b4d8af" hostname: ci-ln-9gp362t-72292-v2p94-master-2 Encap geneve ip: "10.0.0.4" options: {csum="true"} Port_Binding tstor-ci-ln-9gp362t-72292-v2p94-master-2 Chassis "1d371cb8-5e21-44fd-9025-c4b162cc4247" hostname: ci-ln-9gp362t-72292-v2p94-master-1 Encap geneve ip: "10.0.0.3" options: {csum="true"} Port_Binding tstor-ci-ln-9gp362t-72292-v2p94-master-1
This detailed output shows the chassis and the ports that are attached to the chassis which in this case are all of the router ports and anything that runs like host networking. Any pods communicate out to the wider network using source network address translation (SNAT). Their IP address is translated into the IP address of the node that the pod is running on and then sent out into the network.
In addition to the chassis information the southbound database has all the logic flows and those logic flows are then sent to the
ovn-controller
running on each of the nodes. Theovn-controller
translates the logic flows into open flow rules and ultimately programsOpenvSwitch
so that your pods can then follow open flow rules and make it out of the network.Run the following command to display the options available with the command
ovn-sbctl
:$ oc exec -n openshift-ovn-kubernetes -it ovnkube-node-55xs2 \ -c sbdb ovn-sbctl --help
20.2.6. Command line arguments for ovn-sbctl to examine southbound database contents
The following table describes the command line arguments that can be used with ovn-sbctl
to examine the contents of the southbound database.
Open a remote shell in the pod you wish to view the contents of and then run the ovn-sbctl
commands.
Argument | Description |
---|---|
| An overview of the southbound database contents as seen from a specific node. |
| List the contents of southbound database for a the specified port . |
| List the logical flows. |
20.2.7. OVN-Kubernetes logical architecture
OVN is a network virtualization solution. It creates logical switches and routers. These switches and routers are interconnected to create any network topologies. When you run ovnkube-trace
with the log level set to 2 or 5 the OVN-Kubernetes logical components are exposed. The following diagram shows how the routers and switches are connected in OpenShift Container Platform.
Figure 20.2. OVN-Kubernetes router and switch components
The key components involved in packet processing are:
- Gateway routers
-
Gateway routers sometimes called L3 gateway routers, are typically used between the distributed routers and the physical network. Gateway routers including their logical patch ports are bound to a physical location (not distributed), or chassis. The patch ports on this router are known as l3gateway ports in the ovn-southbound database (
ovn-sbdb
). - Distributed logical routers
- Distributed logical routers and the logical switches behind them, to which virtual machines and containers attach, effectively reside on each hypervisor.
- Join local switch
- Join local switches are used to connect the distributed router and gateway routers. It reduces the number of IP addresses needed on the distributed router.
- Logical switches with patch ports
- Logical switches with patch ports are used to virtualize the network stack. They connect remote logical ports through tunnels.
- Logical switches with localnet ports
- Logical switches with localnet ports are used to connect OVN to the physical network. They connect remote logical ports by bridging the packets to directly connected physical L2 segments using localnet ports.
- Patch ports
- Patch ports represent connectivity between logical switches and logical routers and between peer logical routers. A single connection has a pair of patch ports at each such point of connectivity, one on each side.
- l3gateway ports
-
l3gateway ports are the port binding entries in the
ovn-sbdb
for logical patch ports used in the gateway routers. They are called l3gateway ports rather than patch ports just to portray the fact that these ports are bound to a chassis just like the gateway router itself. - localnet ports
-
localnet ports are present on the bridged logical switches that allows a connection to a locally accessible network from each
ovn-controller
instance. This helps model the direct connectivity to the physical network from the logical switches. A logical switch can only have a single localnet port attached to it.
20.2.7.1. Installing network-tools on local host
Install network-tools
on your local host to make a collection of tools available for debugging OpenShift Container Platform cluster network issues.
Procedure
Clone the
network-tools
repository onto your workstation with the following command:$ git clone git@github.com:openshift/network-tools.git
Change into the directory for the repository you just cloned:
$ cd network-tools
Optional: List all available commands:
$ ./debug-scripts/network-tools -h
20.2.7.2. Running network-tools
Get information about the logical switches and routers by running network-tools
.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster as a user with
cluster-admin
privileges. -
You have installed
network-tools
on local host.
Procedure
List the routers by running the following command:
$ ./debug-scripts/network-tools ovn-db-run-command ovn-nbctl lr-list
Example output
944a7b53-7948-4ad2-a494-82b55eeccf87 (GR_ci-ln-54932yb-72292-kd676-worker-c-rzj99) 84bd4a4c-4b0b-4a47-b0cf-a2c32709fc53 (ovn_cluster_router)
List the localnet ports by running the following command:
$ ./debug-scripts/network-tools ovn-db-run-command \ ovn-sbctl find Port_Binding type=localnet
Example output
_uuid : d05298f5-805b-4838-9224-1211afc2f199 additional_chassis : [] additional_encap : [] chassis : [] datapath : f3c2c959-743b-4037-854d-26627902597c encap : [] external_ids : {} gateway_chassis : [] ha_chassis_group : [] logical_port : br-ex_ci-ln-54932yb-72292-kd676-worker-c-rzj99 mac : [unknown] mirror_rules : [] nat_addresses : [] options : {network_name=physnet} parent_port : [] port_security : [] requested_additional_chassis: [] requested_chassis : [] tag : [] tunnel_key : 2 type : localnet up : false virtual_parent : [] [...]
List the
l3gateway
ports by running the following command:$ ./debug-scripts/network-tools ovn-db-run-command \ ovn-sbctl find Port_Binding type=l3gateway
Example output
_uuid : 5207a1f3-1cf3-42f1-83e9-387bbb06b03c additional_chassis : [] additional_encap : [] chassis : ca6eb600-3a10-4372-a83e-e0d957c4cd92 datapath : f3c2c959-743b-4037-854d-26627902597c encap : [] external_ids : {} gateway_chassis : [] ha_chassis_group : [] logical_port : etor-GR_ci-ln-54932yb-72292-kd676-worker-c-rzj99 mac : ["42:01:0a:00:80:04"] mirror_rules : [] nat_addresses : ["42:01:0a:00:80:04 10.0.128.4"] options : {l3gateway-chassis="84737c36-b383-4c83-92c5-2bd5b3c7e772", peer=rtoe-GR_ci-ln-54932yb-72292-kd676-worker-c-rzj99} parent_port : [] port_security : [] requested_additional_chassis: [] requested_chassis : [] tag : [] tunnel_key : 1 type : l3gateway up : true virtual_parent : [] _uuid : 6088d647-84f2-43f2-b53f-c9d379042679 additional_chassis : [] additional_encap : [] chassis : ca6eb600-3a10-4372-a83e-e0d957c4cd92 datapath : dc9cea00-d94a-41b8-bdb0-89d42d13aa2e encap : [] external_ids : {} gateway_chassis : [] ha_chassis_group : [] logical_port : jtor-GR_ci-ln-54932yb-72292-kd676-worker-c-rzj99 mac : [router] mirror_rules : [] nat_addresses : [] options : {l3gateway-chassis="84737c36-b383-4c83-92c5-2bd5b3c7e772", peer=rtoj-GR_ci-ln-54932yb-72292-kd676-worker-c-rzj99} parent_port : [] port_security : [] requested_additional_chassis: [] requested_chassis : [] tag : [] tunnel_key : 2 type : l3gateway up : true virtual_parent : [] [...]
List the patch ports by running the following command:
$ ./debug-scripts/network-tools ovn-db-run-command \ ovn-sbctl find Port_Binding type=patch
Example output
_uuid : 785fb8b6-ee5a-4792-a415-5b1cb855dac2 additional_chassis : [] additional_encap : [] chassis : [] datapath : f1ddd1cc-dc0d-43b4-90ca-12651305acec encap : [] external_ids : {} gateway_chassis : [] ha_chassis_group : [] logical_port : stor-ci-ln-54932yb-72292-kd676-worker-c-rzj99 mac : [router] mirror_rules : [] nat_addresses : ["0a:58:0a:80:02:01 10.128.2.1 is_chassis_resident(\"cr-rtos-ci-ln-54932yb-72292-kd676-worker-c-rzj99\")"] options : {peer=rtos-ci-ln-54932yb-72292-kd676-worker-c-rzj99} parent_port : [] port_security : [] requested_additional_chassis: [] requested_chassis : [] tag : [] tunnel_key : 1 type : patch up : false virtual_parent : [] _uuid : c01ff587-21a5-40b4-8244-4cd0425e5d9a additional_chassis : [] additional_encap : [] chassis : [] datapath : f6795586-bf92-4f84-9222-efe4ac6a7734 encap : [] external_ids : {} gateway_chassis : [] ha_chassis_group : [] logical_port : rtoj-ovn_cluster_router mac : ["0a:58:64:40:00:01 100.64.0.1/16"] mirror_rules : [] nat_addresses : [] options : {peer=jtor-ovn_cluster_router} parent_port : [] port_security : [] requested_additional_chassis: [] requested_chassis : [] tag : [] tunnel_key : 1 type : patch up : false virtual_parent : [] [...]
20.2.8. Additional resources
20.3. Troubleshooting OVN-Kubernetes
OVN-Kubernetes has many sources of built-in health checks and logs. Follow the instructions in these sections to examine your cluster. If a support case is necessary, follow the support guide to collect additional information through a must-gather
. Only use the -- gather_network_logs
when instructed by support.
20.3.1. Monitoring OVN-Kubernetes health by using readiness probes
The ovnkube-control-plane
and ovnkube-node
pods have containers configured with readiness probes.
Prerequisites
-
Access to the OpenShift CLI (
oc
). -
You have access to the cluster with
cluster-admin
privileges. -
You have installed
jq
.
Procedure
Review the details of the
ovnkube-node
readiness probe by running the following command:$ oc get pods -n openshift-ovn-kubernetes -l app=ovnkube-node \ -o json | jq '.items[0].spec.containers[] | .name,.readinessProbe'
The readiness probe for the northbound and southbound database containers in the
ovnkube-node
pod checks for the health of the databases and theovnkube-controller
container.The
ovnkube-controller
container in theovnkube-node
pod has a readiness probe to verify the presence of the OVN-Kubernetes CNI configuration file, the absence of which would indicate that the pod is not running or is not ready to accept requests to configure pods.Show all events including the probe failures, for the namespace by using the following command:
$ oc get events -n openshift-ovn-kubernetes
Show the events for just a specific pod:
$ oc describe pod ovnkube-node-9lqfk -n openshift-ovn-kubernetes
Show the messages and statuses from the cluster network operator:
$ oc get co/network -o json | jq '.status.conditions[]'
Show the
ready
status of each container inovnkube-node
pods by running the following script:$ for p in $(oc get pods --selector app=ovnkube-node -n openshift-ovn-kubernetes \ -o jsonpath='{range.items[*]}{" "}{.metadata.name}'); do echo === $p ===; \ oc get pods -n openshift-ovn-kubernetes $p -o json | jq '.status.containerStatuses[] | .name, .ready'; \ done
NoteThe expectation is all container statuses are reporting as
true
. Failure of a readiness probe sets the status tofalse
.
Additional resources
20.3.2. Viewing OVN-Kubernetes alerts in the console
The Alerting UI provides detailed information about alerts and their governing alerting rules and silences.
Prerequisites
- You have access to the cluster as a developer or as a user with view permissions for the project that you are viewing metrics for.
Procedure (UI)
-
In the Administrator perspective, select Observe
Alerting. The three main pages in the Alerting UI in this perspective are the Alerts, Silences, and Alerting Rules pages. -
View the rules for OVN-Kubernetes alerts by selecting Observe
Alerting Alerting Rules.
20.3.3. Viewing OVN-Kubernetes alerts in the CLI
You can get information about alerts and their governing alerting rules and silences from the command line.
Prerequisites
-
Access to the cluster as a user with the
cluster-admin
role. -
The OpenShift CLI (
oc
) installed. -
You have installed
jq
.
Procedure
View active or firing alerts by running the following commands.
Set the alert manager route environment variable by running the following command:
$ ALERT_MANAGER=$(oc get route alertmanager-main -n openshift-monitoring \ -o jsonpath='{@.spec.host}')
Issue a
curl
request to the alert manager route API by running the following command, replacing$ALERT_MANAGER
with the URL of yourAlertmanager
instance:$ curl -s -k -H "Authorization: Bearer $(oc create token prometheus-k8s -n openshift-monitoring)" https://$ALERT_MANAGER/api/v1/alerts | jq '.data[] | "\(.labels.severity) \(.labels.alertname) \(.labels.pod) \(.labels.container) \(.labels.endpoint) \(.labels.instance)"'
View alerting rules by running the following command:
$ oc -n openshift-monitoring exec -c prometheus prometheus-k8s-0 -- curl -s 'http://localhost:9090/api/v1/rules' | jq '.data.groups[].rules[] | select(((.name|contains("ovn")) or (.name|contains("OVN")) or (.name|contains("Ovn")) or (.name|contains("North")) or (.name|contains("South"))) and .type=="alerting")'
20.3.4. Viewing the OVN-Kubernetes logs using the CLI
You can view the logs for each of the pods in the ovnkube-master
and ovnkube-node
pods using the OpenShift CLI (oc
).
Prerequisites
-
Access to the cluster as a user with the
cluster-admin
role. -
Access to the OpenShift CLI (
oc
). -
You have installed
jq
.
Procedure
View the log for a specific pod:
$ oc logs -f <pod_name> -c <container_name> -n <namespace>
where:
-f
- Optional: Specifies that the output follows what is being written into the logs.
<pod_name>
- Specifies the name of the pod.
<container_name>
- Optional: Specifies the name of a container. When a pod has more than one container, you must specify the container name.
<namespace>
- Specify the namespace the pod is running in.
For example:
$ oc logs ovnkube-node-5dx44 -n openshift-ovn-kubernetes
$ oc logs -f ovnkube-node-5dx44 -c ovnkube-controller -n openshift-ovn-kubernetes
The contents of log files are printed out.
Examine the most recent entries in all the containers in the
ovnkube-node
pods:$ for p in $(oc get pods --selector app=ovnkube-node -n openshift-ovn-kubernetes \ -o jsonpath='{range.items[*]}{" "}{.metadata.name}'); \ do echo === $p ===; for container in $(oc get pods -n openshift-ovn-kubernetes $p \ -o json | jq -r '.status.containerStatuses[] | .name');do echo ---$container---; \ oc logs -c $container $p -n openshift-ovn-kubernetes --tail=5; done; done
View the last 5 lines of every log in every container in an
ovnkube-node
pod using the following command:$ oc logs -l app=ovnkube-node -n openshift-ovn-kubernetes --all-containers --tail 5
20.3.5. Viewing the OVN-Kubernetes logs using the web console
You can view the logs for each of the pods in the ovnkube-master
and ovnkube-node
pods in the web console.
Prerequisites
-
Access to the OpenShift CLI (
oc
).
Procedure
-
In the OpenShift Container Platform console, navigate to Workloads
Pods or navigate to the pod through the resource you want to investigate. -
Select the
openshift-ovn-kubernetes
project from the drop-down menu. - Click the name of the pod you want to investigate.
-
Click Logs. By default for the
ovnkube-master
the logs associated with thenorthd
container are displayed. - Use the down-down menu to select logs for each container in turn.
20.3.5.1. Changing the OVN-Kubernetes log levels
The default log level for OVN-Kubernetes is 4. To debug OVN-Kubernetes, set the log level to 5. Follow this procedure to increase the log level of the OVN-Kubernetes to help you debug an issue.
Prerequisites
-
You have access to the cluster with
cluster-admin
privileges. - You have access to the OpenShift Container Platform web console.
Procedure
Run the following command to get detailed information for all pods in the OVN-Kubernetes project:
$ oc get po -o wide -n openshift-ovn-kubernetes
Example output
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES ovnkube-control-plane-65497d4548-9ptdr 2/2 Running 2 (128m ago) 147m 10.0.0.3 ci-ln-3njdr9b-72292-5nwkp-master-0 <none> <none> ovnkube-control-plane-65497d4548-j6zfk 2/2 Running 0 147m 10.0.0.5 ci-ln-3njdr9b-72292-5nwkp-master-2 <none> <none> ovnkube-node-5dx44 8/8 Running 0 146m 10.0.0.3 ci-ln-3njdr9b-72292-5nwkp-master-0 <none> <none> ovnkube-node-dpfn4 8/8 Running 0 146m 10.0.0.4 ci-ln-3njdr9b-72292-5nwkp-master-1 <none> <none> ovnkube-node-kwc9l 8/8 Running 0 134m 10.0.128.2 ci-ln-3njdr9b-72292-5nwkp-worker-a-2fjcj <none> <none> ovnkube-node-mcrhl 8/8 Running 0 134m 10.0.128.4 ci-ln-3njdr9b-72292-5nwkp-worker-c-v9x5v <none> <none> ovnkube-node-nsct4 8/8 Running 0 146m 10.0.0.5 ci-ln-3njdr9b-72292-5nwkp-master-2 <none> <none> ovnkube-node-zrj9f 8/8 Running 0 134m 10.0.128.3 ci-ln-3njdr9b-72292-5nwkp-worker-b-v78h7 <none> <none>
Create a
ConfigMap
file similar to the following example and use a filename such asenv-overrides.yaml
:Example
ConfigMap
filekind: ConfigMap apiVersion: v1 metadata: name: env-overrides namespace: openshift-ovn-kubernetes data: ci-ln-3njdr9b-72292-5nwkp-master-0: | 1 # This sets the log level for the ovn-kubernetes node process: OVN_KUBE_LOG_LEVEL=5 # You might also/instead want to enable debug logging for ovn-controller: OVN_LOG_LEVEL=dbg ci-ln-3njdr9b-72292-5nwkp-master-2: | # This sets the log level for the ovn-kubernetes node process: OVN_KUBE_LOG_LEVEL=5 # You might also/instead want to enable debug logging for ovn-controller: OVN_LOG_LEVEL=dbg _master: | 2 # This sets the log level for the ovn-kubernetes master process as well as the ovn-dbchecker: OVN_KUBE_LOG_LEVEL=5 # You might also/instead want to enable debug logging for northd, nbdb and sbdb on all masters: OVN_LOG_LEVEL=dbg
Apply the
ConfigMap
file by using the following command:$ oc apply -n openshift-ovn-kubernetes -f env-overrides.yaml
Example output
configmap/env-overrides.yaml created
Restart the
ovnkube
pods to apply the new log level by using the following commands:$ oc delete pod -n openshift-ovn-kubernetes \ --field-selector spec.nodeName=ci-ln-3njdr9b-72292-5nwkp-master-0 -l app=ovnkube-node
$ oc delete pod -n openshift-ovn-kubernetes \ --field-selector spec.nodeName=ci-ln-3njdr9b-72292-5nwkp-master-2 -l app=ovnkube-node
$ oc delete pod -n openshift-ovn-kubernetes -l app=ovnkube-node
To verify that the `ConfigMap`file has been applied to all nodes for a specific pod, run the following command:
$ oc logs -n openshift-ovn-kubernetes --all-containers --prefix ovnkube-node-<xxxx> | grep -E -m 10 '(Logging config:|vconsole|DBG)'
where:
<XXXX>
Specifies the random sequence of letters for a pod from the previous step.
Example output
[pod/ovnkube-node-2cpjc/sbdb] + exec /usr/share/ovn/scripts/ovn-ctl --no-monitor '--ovn-sb-log=-vconsole:info -vfile:off -vPATTERN:console:%D{%Y-%m-%dT%H:%M:%S.###Z}|%05N|%c%T|%p|%m' run_sb_ovsdb [pod/ovnkube-node-2cpjc/ovnkube-controller] I1012 14:39:59.984506 35767 config.go:2247] Logging config: {File: CNIFile:/var/log/ovn-kubernetes/ovn-k8s-cni-overlay.log LibovsdbFile:/var/log/ovnkube/libovsdb.log Level:5 LogFileMaxSize:100 LogFileMaxBackups:5 LogFileMaxAge:0 ACLLoggingRateLimit:20} [pod/ovnkube-node-2cpjc/northd] + exec ovn-northd --no-chdir -vconsole:info -vfile:off '-vPATTERN:console:%D{%Y-%m-%dT%H:%M:%S.###Z}|%05N|%c%T|%p|%m' --pidfile /var/run/ovn/ovn-northd.pid --n-threads=1 [pod/ovnkube-node-2cpjc/nbdb] + exec /usr/share/ovn/scripts/ovn-ctl --no-monitor '--ovn-nb-log=-vconsole:info -vfile:off -vPATTERN:console:%D{%Y-%m-%dT%H:%M:%S.###Z}|%05N|%c%T|%p|%m' run_nb_ovsdb [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.552Z|00002|hmap|DBG|lib/shash.c:114: 1 bucket with 6+ nodes, including 1 bucket with 6 nodes (32 nodes total across 32 buckets) [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.553Z|00003|hmap|DBG|lib/shash.c:114: 1 bucket with 6+ nodes, including 1 bucket with 6 nodes (64 nodes total across 64 buckets) [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.553Z|00004|hmap|DBG|lib/shash.c:114: 1 bucket with 6+ nodes, including 1 bucket with 7 nodes (32 nodes total across 32 buckets) [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.553Z|00005|reconnect|DBG|unix:/var/run/openvswitch/db.sock: entering BACKOFF [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.553Z|00007|reconnect|DBG|unix:/var/run/openvswitch/db.sock: entering CONNECTING [pod/ovnkube-node-2cpjc/ovn-controller] 2023-10-12T14:39:54.553Z|00008|ovsdb_cs|DBG|unix:/var/run/openvswitch/db.sock: SERVER_SCHEMA_REQUESTED -> SERVER_SCHEMA_REQUESTED at lib/ovsdb-cs.c:423
Optional: Check the
ConfigMap
file has been applied by running the following command:for f in $(oc -n openshift-ovn-kubernetes get po -l 'app=ovnkube-node' --no-headers -o custom-columns=N:.metadata.name) ; do echo "---- $f ----" ; oc -n openshift-ovn-kubernetes exec -c ovnkube-controller $f -- pgrep -a -f init-ovnkube-controller | grep -P -o '^.*loglevel\s+\d' ; done
Example output
---- ovnkube-node-2dt57 ---- 60981 /usr/bin/ovnkube --init-ovnkube-controller xpst8-worker-c-vmh5n.c.openshift-qe.internal --init-node xpst8-worker-c-vmh5n.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 4 ---- ovnkube-node-4zznh ---- 178034 /usr/bin/ovnkube --init-ovnkube-controller xpst8-master-2.c.openshift-qe.internal --init-node xpst8-master-2.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 4 ---- ovnkube-node-548sx ---- 77499 /usr/bin/ovnkube --init-ovnkube-controller xpst8-worker-a-fjtnb.c.openshift-qe.internal --init-node xpst8-worker-a-fjtnb.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 4 ---- ovnkube-node-6btrf ---- 73781 /usr/bin/ovnkube --init-ovnkube-controller xpst8-worker-b-p8rww.c.openshift-qe.internal --init-node xpst8-worker-b-p8rww.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 4 ---- ovnkube-node-fkc9r ---- 130707 /usr/bin/ovnkube --init-ovnkube-controller xpst8-master-0.c.openshift-qe.internal --init-node xpst8-master-0.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 5 ---- ovnkube-node-tk9l4 ---- 181328 /usr/bin/ovnkube --init-ovnkube-controller xpst8-master-1.c.openshift-qe.internal --init-node xpst8-master-1.c.openshift-qe.internal --config-file=/run/ovnkube-config/ovnkube.conf --ovn-empty-lb-events --loglevel 4
20.3.6. Checking the OVN-Kubernetes pod network connectivity
The connectivity check controller, in OpenShift Container Platform 4.10 and later, orchestrates connection verification checks in your cluster. These include Kubernetes API, OpenShift API and individual nodes. The results for the connection tests are stored in PodNetworkConnectivity
objects in the openshift-network-diagnostics
namespace. Connection tests are performed every minute in parallel.
Prerequisites
-
Access to the OpenShift CLI (
oc
). -
Access to the cluster as a user with the
cluster-admin
role. -
You have installed
jq
.
Procedure
To list the current
PodNetworkConnectivityCheck
objects, enter the following command:$ oc get podnetworkconnectivitychecks -n openshift-network-diagnostics
View the most recent success for each connection object by using the following command:
$ oc get podnetworkconnectivitychecks -n openshift-network-diagnostics \ -o json | jq '.items[]| .spec.targetEndpoint,.status.successes[0]'
View the most recent failures for each connection object by using the following command:
$ oc get podnetworkconnectivitychecks -n openshift-network-diagnostics \ -o json | jq '.items[]| .spec.targetEndpoint,.status.failures[0]'
View the most recent outages for each connection object by using the following command:
$ oc get podnetworkconnectivitychecks -n openshift-network-diagnostics \ -o json | jq '.items[]| .spec.targetEndpoint,.status.outages[0]'
The connectivity check controller also logs metrics from these checks into Prometheus.
View all the metrics by running the following command:
$ oc exec prometheus-k8s-0 -n openshift-monitoring -- \ promtool query instant http://localhost:9090 \ '{component="openshift-network-diagnostics"}'
View the latency between the source pod and the openshift api service for the last 5 minutes:
$ oc exec prometheus-k8s-0 -n openshift-monitoring -- \ promtool query instant http://localhost:9090 \ '{component="openshift-network-diagnostics"}'
20.3.7. Additional resources
20.4. Tracing Openflow with ovnkube-trace
OVN and OVS traffic flows can be simulated in a single utility called ovnkube-trace
. The ovnkube-trace
utility runs ovn-trace
, ovs-appctl ofproto/trace
and ovn-detrace
and correlates that information in a single output.
You can execute the ovnkube-trace
binary from a dedicated container. For releases after OpenShift Container Platform 4.7, you can also copy the binary to a local host and execute it from that host.
20.4.1. Installing the ovnkube-trace on local host
The ovnkube-trace
tool traces packet simulations for arbitrary UDP or TCP traffic between points in an OVN-Kubernetes driven OpenShift Container Platform cluster. Copy the ovnkube-trace
binary to your local host making it available to run against the cluster.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges.
Procedure
Create a pod variable by using the following command:
$ POD=$(oc get pods -n openshift-ovn-kubernetes -l app=ovnkube-control-plane -o name | head -1 | awk -F '/' '{print $NF}')
Run the following command on your local host to copy the binary from the
ovnkube-control-plane
pods:$ oc cp -n openshift-ovn-kubernetes $POD:/usr/bin/ovnkube-trace -c ovnkube-cluster-manager ovnkube-trace
NoteIf you are using Red Hat Enterprise Linux (RHEL) 8 to run the
ovnkube-trace
tool, you must copy the file/usr/lib/rhel8/ovnkube-trace
to your local host.Make
ovnkube-trace
executable by running the following command:$ chmod +x ovnkube-trace
Display the options available with
ovnkube-trace
by running the following command:$ ./ovnkube-trace -help
Expected output
Usage of ./ovnkube-trace: -addr-family string Address family (ip4 or ip6) to be used for tracing (default "ip4") -dst string dest: destination pod name -dst-ip string destination IP address (meant for tests to external targets) -dst-namespace string k8s namespace of dest pod (default "default") -dst-port string dst-port: destination port (default "80") -kubeconfig string absolute path to the kubeconfig file -loglevel string loglevel: klog level (default "0") -ovn-config-namespace string namespace used by ovn-config itself -service string service: destination service name -skip-detrace skip ovn-detrace command -src string src: source pod name -src-namespace string k8s namespace of source pod (default "default") -tcp use tcp transport protocol -udp use udp transport protocol
The command-line arguments supported are familiar Kubernetes constructs, such as namespaces, pods, services so you do not need to find the MAC address, the IP address of the destination nodes, or the ICMP type.
The log levels are:
- 0 (minimal output)
- 2 (more verbose output showing results of trace commands)
- 5 (debug output)
20.4.2. Running ovnkube-trace
Run ovn-trace
to simulate packet forwarding within an OVN logical network.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges. -
You have installed
ovnkube-trace
on local host
Example: Testing that DNS resolution works from a deployed pod
This example illustrates how to test the DNS resolution from a deployed pod to the core DNS pod that runs in the cluster.
Procedure
Start a web service in the default namespace by entering the following command:
$ oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80
List the pods running in the
openshift-dns
namespace:oc get pods -n openshift-dns
Example output
NAME READY STATUS RESTARTS AGE dns-default-8s42x 2/2 Running 0 5h8m dns-default-mdw6r 2/2 Running 0 4h58m dns-default-p8t5h 2/2 Running 0 4h58m dns-default-rl6nk 2/2 Running 0 5h8m dns-default-xbgqx 2/2 Running 0 5h8m dns-default-zv8f6 2/2 Running 0 4h58m node-resolver-62jjb 1/1 Running 0 5h8m node-resolver-8z4cj 1/1 Running 0 4h59m node-resolver-bq244 1/1 Running 0 5h8m node-resolver-hc58n 1/1 Running 0 4h59m node-resolver-lm6z4 1/1 Running 0 5h8m node-resolver-zfx5k 1/1 Running 0 5h
Run the following
ovnkube-trace
command to verify DNS resolution is working:$ ./ovnkube-trace \ -src-namespace default \ 1 -src web \ 2 -dst-namespace openshift-dns \ 3 -dst dns-default-p8t5h \ 4 -udp -dst-port 53 \ 5 -loglevel 0 6
Example output if the
src&dst
pod lands on the same nodeovn-trace source pod to destination pod indicates success from web to dns-default-p8t5h ovn-trace destination pod to source pod indicates success from dns-default-p8t5h to web ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-p8t5h ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-p8t5h to web ovn-detrace source pod to destination pod indicates success from web to dns-default-p8t5h ovn-detrace destination pod to source pod indicates success from dns-default-p8t5h to web
Example output if the
src&dst
pod lands on a different nodeovn-trace source pod to destination pod indicates success from web to dns-default-8s42x ovn-trace (remote) source pod to destination pod indicates success from web to dns-default-8s42x ovn-trace destination pod to source pod indicates success from dns-default-8s42x to web ovn-trace (remote) destination pod to source pod indicates success from dns-default-8s42x to web ovs-appctl ofproto/trace source pod to destination pod indicates success from web to dns-default-8s42x ovs-appctl ofproto/trace destination pod to source pod indicates success from dns-default-8s42x to web ovn-detrace source pod to destination pod indicates success from web to dns-default-8s42x ovn-detrace destination pod to source pod indicates success from dns-default-8s42x to web
The ouput indicates success from the deployed pod to the DNS port and also indicates that it is successful going back in the other direction. So you know bi-directional traffic is supported on UDP port 53 if my web pod wants to do dns resolution from core DNS.
If for example that did not work and you wanted to get the ovn-trace
, the ovs-appctl
of proto/trace
and ovn-detrace
, and more debug type information increase the log level to 2 and run the command again as follows:
$ ./ovnkube-trace \ -src-namespace default \ -src web \ -dst-namespace openshift-dns \ -dst dns-default-467qw \ -udp -dst-port 53 \ -loglevel 2
The output from this increased log level is too much to list here. In a failure situation the output of this command shows which flow is dropping that traffic. For example an egress or ingress network policy may be configured on the cluster that does not allow that traffic.
Example: Verifying by using debug output a configured default deny
This example illustrates how to identify by using the debug output that an ingress default deny policy blocks traffic.
Procedure
Create the following YAML that defines a
deny-by-default
policy to deny ingress from all pods in all namespaces. Save the YAML in thedeny-by-default.yaml
file:kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: deny-by-default namespace: default spec: podSelector: {} ingress: []
Apply the policy by entering the following command:
$ oc apply -f deny-by-default.yaml
Example output
networkpolicy.networking.k8s.io/deny-by-default created
Start a web service in the
default
namespace by entering the following command:$ oc run web --namespace=default --image=quay.io/openshifttest/nginx --labels="app=web" --expose --port=80
Run the following command to create the
prod
namespace:$ oc create namespace prod
Run the following command to label the
prod
namespace:$ oc label namespace/prod purpose=production
Run the following command to deploy an
alpine
image in theprod
namespace and start a shell:$ oc run test-6459 --namespace=prod --rm -i -t --image=alpine -- sh
- Open another terminal session.
In this new terminal session run
ovn-trace
to verify the failure in communication between the source podtest-6459
running in namespaceprod
and destination pod running in thedefault
namespace:$ ./ovnkube-trace \ -src-namespace prod \ -src test-6459 \ -dst-namespace default \ -dst web \ -tcp -dst-port 80 \ -loglevel 0
Example output
ovn-trace source pod to destination pod indicates failure from test-6459 to web
Increase the log level to 2 to expose the reason for the failure by running the following command:
$ ./ovnkube-trace \ -src-namespace prod \ -src test-6459 \ -dst-namespace default \ -dst web \ -tcp -dst-port 80 \ -loglevel 2
Example output
... ------------------------------------------------ 3. ls_out_acl_hint (northd.c:7454): !ct.new && ct.est && !ct.rpl && ct_mark.blocked == 0, priority 4, uuid 12efc456 reg0[8] = 1; reg0[10] = 1; next; 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 0, priority 500, uuid 69372c5d reg8[30..31] = 1; next(4); 5. ls_out_acl_action (northd.c:7835): reg8[30..31] == 1, priority 500, uuid 2fa0af89 reg8[30..31] = 2; next(4); 4. ls_out_acl_eval (northd.c:7691): reg8[30..31] == 2 && reg0[10] == 1 && (outport == @a16982411286042166782_ingressDefaultDeny), priority 2000, uuid 447d0dab reg8[17] = 1; ct_commit { ct_mark.blocked = 1; }; 1 next; ...
- 1
- Ingress traffic is blocked due to the default deny policy being in place.
Create a policy that allows traffic from all pods in a particular namespaces with a label
purpose=production
. Save the YAML in theweb-allow-prod.yaml
file:kind: NetworkPolicy apiVersion: networking.k8s.io/v1 metadata: name: web-allow-prod namespace: default spec: podSelector: matchLabels: app: web policyTypes: - Ingress ingress: - from: - namespaceSelector: matchLabels: purpose: production
Apply the policy by entering the following command:
$ oc apply -f web-allow-prod.yaml
Run
ovnkube-trace
to verify that traffic is now allowed by entering the following command:$ ./ovnkube-trace \ -src-namespace prod \ -src test-6459 \ -dst-namespace default \ -dst web \ -tcp -dst-port 80 \ -loglevel 0
Expected output
ovn-trace source pod to destination pod indicates success from test-6459 to web ovn-trace destination pod to source pod indicates success from web to test-6459 ovs-appctl ofproto/trace source pod to destination pod indicates success from test-6459 to web ovs-appctl ofproto/trace destination pod to source pod indicates success from web to test-6459 ovn-detrace source pod to destination pod indicates success from test-6459 to web ovn-detrace destination pod to source pod indicates success from web to test-6459
Run the following command in the shell that was opened in step six to connect nginx to the web-server:
wget -qO- --timeout=2 http://web.default
Expected output
<!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html>
20.4.3. Additional resources
20.5. Converting to IPv4/IPv6 dual-stack networking
As a cluster administrator, you can convert your IPv4 single-stack cluster to a dual-network cluster network that supports IPv4 and IPv6 address families. After converting to dual-stack networking, new and existing pods have dual-stack networking enabled.
When using dual-stack networking where IPv6 is required, you cannot use IPv4-mapped IPv6 addresses, such as ::FFFF:198.51.100.1
.
Additional resources
- For more information about platform-specific support for dual-stack networking, see OVN-Kubernetes purpose
20.5.1. Converting to a dual-stack cluster network
As a cluster administrator, you can convert your single-stack cluster network to a dual-stack cluster network.
After converting your cluster to use dual-stack networking, you must re-create any existing pods for them to receive IPv6 addresses, because only new pods are assigned IPv6 addresses.
Converting a single-stack cluster network to a dual-stack cluster network consists of creating patches and applying them to the cluster’s network and infrastructure. You can convert to a dual-stack cluster network for a cluster that runs on installer-provisioned infrastructure.
Each patch operation that changes clusterNetwork
, serviceNetwork
, apiServerInternalIPs
, and ingressIP
objects triggers a restart of the cluster. Changing the MachineNetworks
object does not cause a reboot of the cluster.
If you need to add IPv6 virtual IPs (VIPs) for API and Ingress services to an existing dual-stack-configured cluster, you need to patch only the cluster’s infrastructure and not the cluster’s network.
If you already upgraded your cluster to OpenShift Container Platform 4.16 or later and you need to convert the single-stack cluster network to a dual-stack cluster network, you must specify an existing IPv4 machineNetwork
network configuration from the install-config.yaml
file for API and Ingress services in the YAML configuration patch file. This configuration ensures that IPv4 traffic exists in the same network interface as the default gateway.
Example YAML configuration file with an added IPv4 address block for the machineNetwork
network
- op: add
path: /spec/platformSpec/baremetal/machineNetworks/- 1
value: 192.168.1.0/24
# ...
- 1
- Ensure that you specify an address block for the
machineNetwork
network where your machines operate. You must select both API and Ingress IP addresses for the machine network.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges. - Your cluster uses the OVN-Kubernetes network plugin.
- The cluster nodes have IPv6 addresses.
- You have configured an IPv6-enabled router based on your infrastructure.
Procedure
To specify IPv6 address blocks for cluster and service networks, create a YAML configuration patch file that has a similar configuration to the following example:
- op: add path: /spec/clusterNetwork/- value: 1 cidr: fd01::/48 hostPrefix: 64 - op: add path: /spec/serviceNetwork/- value: fd02::/112 2
- 1
- Specify an object with the
cidr
andhostPrefix
fields. The host prefix must be64
or greater. The IPv6 Classless Inter-Domain Routing (CIDR) prefix must be large enough to accommodate the specified host prefix. - 2
- Specify an IPv6 CIDR with a prefix of
112
. Kubernetes uses only the lowest 16 bits. For a prefix of112
, IP addresses are assigned from112
to128
bits.
Patch the cluster network configuration by entering the following command in your CLI:
$ oc patch network.config.openshift.io cluster \1 --type='json' --patch-file <file>.yaml
- 1
- Where
file
specifies the name of your created YAML file.
Example output
network.config.openshift.io/cluster patched
Specify IPv6 VIPs for API and Ingress services for your cluster. Create a YAML configuration patch file that has a similar configuration to the following example:
- op: add path: /spec/platformSpec/baremetal/machineNetworks/- 1 value: fd2e:6f44:5dd8::/64 - op: add path: /spec/platformSpec/baremetal/apiServerInternalIPs/- 2 value: fd2e:6f44:5dd8::4 - op: add path: /spec/platformSpec/baremetal/ingressIPs/- value: fd2e:6f44:5dd8::5
- 1
- Ensure that you specify an address block for the
machineNetwork
network where your machines operate. You must select both API and Ingress IP addresses for the machine network. - 2
- Ensure that you specify each file path according to your platform. The example demonstrates a file path on a bare-metal platform.
Patch the infrastructure by entering the following command in your CLI:
$ oc patch infrastructure cluster \1 --type='json' --patch-file <file>.yaml
- 1
- Where
file
specifies the name of your created YAML file.
Example output
infrastructure/cluster patched
Verification
Show the cluster network configuration by entering the following command in your CLI:
$ oc describe network
Verify the successful installation of the patch on the network configuration by checking that the cluster network configuration recognizes the IPv6 address blocks that you specified in the YAML file.
Example output
# ... Status: Cluster Network: Cidr: 10.128.0.0/14 Host Prefix: 23 Cidr: fd01::/48 Host Prefix: 64 Cluster Network MTU: 1400 Network Type: OVNKubernetes Service Network: 172.30.0.0/16 fd02::/112 # ...
Complete the following additional tasks for a cluster that runs on installer-provisioned infrastructure:
Show the cluster infrastructure configuration by entering the following command in your CLI:
$ oc describe infrastructure
Verify the successful installation of the patch on the cluster infrastructure by checking that the infrastructure recognizes the IPv6 address blocks that you specified in the YAML file.
Example output
# ... spec: # ... platformSpec: baremetal: apiServerInternalIPs: - 192.168.123.5 - fd2e:6f44:5dd8::4 ingressIPs: - 192.168.123.10 - fd2e:6f44:5dd8::5 status: # ... platformStatus: baremetal: apiServerInternalIP: 192.168.123.5 apiServerInternalIPs: - 192.168.123.5 - fd2e:6f44:5dd8::4 ingressIP: 192.168.123.10 ingressIPs: - 192.168.123.10 - fd2e:6f44:5dd8::5 # ...
20.5.2. Converting to a single-stack cluster network
As a cluster administrator, you can convert your dual-stack cluster network to a single-stack cluster network.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges. - Your cluster uses the OVN-Kubernetes network plugin.
- The cluster nodes have IPv6 addresses.
- You have enabled dual-stack networking.
Procedure
Edit the
networks.config.openshift.io
custom resource (CR) by running the following command:$ oc edit networks.config.openshift.io
-
Remove the IPv6 specific configuration that you have added to the
cidr
andhostPrefix
fields in the previous procedure.
20.6. Configuring OVN-Kubernetes internal IP address subnets
As a cluster administrator, you can change the IP address ranges that the OVN-Kubernetes network plugin uses for the join and transit subnets.
20.6.1. Configuring the OVN-Kubernetes join subnet
You can change the join subnet used by OVN-Kubernetes to avoid conflicting with any existing subnets already in use in your environment.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in to the cluster with a user with
cluster-admin
privileges. - Ensure that the cluster uses the OVN-Kubernetes network plugin.
Procedure
To change the OVN-Kubernetes join subnet, enter the following command:
$ oc patch network.operator.openshift.io cluster --type='merge' \ -p='{"spec":{"defaultNetwork":{"ovnKubernetesConfig": {"ipv4":{"internalJoinSubnet": "<join_subnet>"}, "ipv6":{"internalJoinSubnet": "<join_subnet>"}}}}}'
where:
<join_subnet>
-
Specifies an IP address subnet for internal use by OVN-Kubernetes. The subnet must be larger than the number of nodes in the cluster and it must be large enough to accommodate one IP address per node in the cluster. This subnet cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv4 is
100.64.0.0/16
and the default value for IPv6 isfd98::/64
.
Example output
network.operator.openshift.io/cluster patched
Verification
To confirm that the configuration is active, enter the following command:
$ oc get network.operator.openshift.io \ -o jsonpath="{.items[0].spec.defaultNetwork}"
It can take up to 30 minutes for this change to take effect.
Example output
{ "ovnKubernetesConfig": { "ipv4": { "internalJoinSubnet": "100.64.1.0/16" }, }, "type": "OVNKubernetes" }
20.6.2. Configuring the OVN-Kubernetes masquerade subnet as a Day 2 operation
You can change the masquerade subnet used by OVN-Kubernetes as a Day 2 operation in order to avoid conflicts with any existing subnets that are already in use in your environment.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in to the cluster as a user with
cluster-admin
privileges.
Procedure
Change your cluster’s masquerade subnet:
For dualstack clusters using IPv6, run the following command:
$ oc patch networks.operator.openshift.io cluster --type=merge -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"ipv4":{"internalMasqueradeSubnet": "<ipv4_masquerade_subnet>"},"ipv6":{"internalMasqueradeSubnet": "<ipv6_masquerade_subnet>"}}}}}}'
where:
ipv4_masquerade_subnet
-
Specifies an IP address to be used as the IPv4 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv4 is
169.254.169.0/29
. ipv6_masquerade_subnet
-
Specifies an IP address to be used as the IPv6 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv6 is
fd69::/125
.
For clusters using IPv4, run the following command:
$ oc patch networks.operator.openshift.io cluster --type=merge -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"ipv4":{"internalMasqueradeSubnet": "<ipv4_masquerade_subnet>"}}}}}}'
where:
ipv4_masquerade_subnet
-
Specifies an IP address to be used as the IPv4 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv4 is
169.254.169.0/29
.
20.6.3. Configuring the OVN-Kubernetes transit subnet
You can change the transit subnet used by OVN-Kubernetes to avoid conflicting with any existing subnets already in use in your environment.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in to the cluster with a user with
cluster-admin
privileges. - Ensure that the cluster uses the OVN-Kubernetes network plugin.
Procedure
To change the OVN-Kubernetes transit subnet, enter the following command:
$ oc patch network.operator.openshift.io cluster --type='merge' \ -p='{"spec":{"defaultNetwork":{"ovnKubernetesConfig": {"ipv4":{"internalTransitSwitchSubnet": "<transit_subnet>"}, "ipv6":{"internalTransitSwitchSubnet": "<transit_subnet>"}}}}}'
where:
<transit_subnet>
-
Specifies an IP address subnet for the distributed transit switch that enables east-west traffic. This subnet cannot overlap with any other subnets used by OVN-Kubernetes or on the host itself. The default value for IPv4 is
100.88.0.0/16
and the default value for IPv6 isfd97::/64
.
Example output
network.operator.openshift.io/cluster patched
Verification
To confirm that the configuration is active, enter the following command:
$ oc get network.operator.openshift.io \ -o jsonpath="{.items[0].spec.defaultNetwork}"
It can take up to 30 minutes for this change to take effect.
Example output
{ "ovnKubernetesConfig": { "ipv4": { "internalTransitSwitchSubnet": "100.88.1.0/16" }, }, "type": "OVNKubernetes" }
20.7. Configure an external gateway on the default network
As a cluster administrator, you can configure an external gateway on the default network.
This feature offers the following benefits:
- Granular control over egress traffic on a per-namespace basis
- Flexible configuration of static and dynamic external gateway IP addresses
- Support for both IPv4 and IPv6 address families
20.7.1. Prerequisites
- Your cluster uses the OVN-Kubernetes network plugin.
- Your infrastructure is configured to route traffic from the secondary external gateway.
20.7.2. How OpenShift Container Platform determines the external gateway IP address
You configure a secondary external gateway with the AdminPolicyBasedExternalRoute
custom resource (CR) from the k8s.ovn.org
API group. The CR supports static and dynamic approaches to specifying an external gateway’s IP address.
Each namespace that a AdminPolicyBasedExternalRoute
CR targets cannot be selected by any other AdminPolicyBasedExternalRoute
CR. A namespace cannot have concurrent secondary external gateways.
Changes to policies are isolated in the controller. If a policy fails to apply, changes to other policies do not trigger a retry of other policies. Policies are only re-evaluated, applying any differences that might have occurred by the change, when updates to the policy itself or related objects to the policy such as target namespaces, pod gateways, or namespaces hosting them from dynamic hops are made.
- Static assignment
- You specify an IP address directly.
- Dynamic assignment
You specify an IP address indirectly, with namespace and pod selectors, and an optional network attachment definition.
- If the name of a network attachment definition is provided, the external gateway IP address of the network attachment is used.
-
If the name of a network attachment definition is not provided, the external gateway IP address for the pod itself is used. However, this approach works only if the pod is configured with
hostNetwork
set totrue
.
20.7.3. AdminPolicyBasedExternalRoute object configuration
You can define an AdminPolicyBasedExternalRoute
object, which is cluster scoped, with the following properties. A namespace can be selected by only one AdminPolicyBasedExternalRoute
CR at a time.
Field | Type | Description |
---|---|---|
|
|
Specifies the name of the |
|
|
Specifies a namespace selector that the routing policies apply to. Only from: namespaceSelector: matchLabels: kubernetes.io/metadata.name: novxlan-externalgw-ecmp-4059
A namespace can only be targeted by one |
|
|
Specifies the destinations where the packets are forwarded to. Must be either or both of |
Field | Type | Description |
---|---|---|
|
| Specifies an array of static IP addresses. |
|
| Specifies an array of pod selectors corresponding to pods configured with a network attachment definition to use as the external gateway target. |
Field | Type | Description |
---|---|---|
|
| Specifies either an IPv4 or IPv6 address of the next destination hop. |
|
|
Optional: Specifies whether Bi-Directional Forwarding Detection (BFD) is supported by the network. The default value is |
Field | Type | Description |
---|---|---|
|
| Specifies a [set-based](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#set-based-requirement) label selector to filter the pods in the namespace that match this network configuration. |
|
|
Specifies a |
|
|
Optional: Specifies whether Bi-Directional Forwarding Detection (BFD) is supported by the network. The default value is |
|
| Optional: Specifies the name of a network attachment definition. The name must match the list of logical networks associated with the pod. If this field is not specified, the host network of the pod is used. However, the pod must be configure as a host network pod to use the host network. |
20.7.3.1. Example secondary external gateway configurations
In the following example, the AdminPolicyBasedExternalRoute
object configures two static IP addresses as external gateways for pods in namespaces with the kubernetes.io/metadata.name: novxlan-externalgw-ecmp-4059
label.
apiVersion: k8s.ovn.org/v1 kind: AdminPolicyBasedExternalRoute metadata: name: default-route-policy spec: from: namespaceSelector: matchLabels: kubernetes.io/metadata.name: novxlan-externalgw-ecmp-4059 nextHops: static: - ip: "172.18.0.8" - ip: "172.18.0.9"
In the following example, the AdminPolicyBasedExternalRoute
object configures a dynamic external gateway. The IP addresses used for the external gateway are derived from the additional network attachments associated with each of the selected pods.
apiVersion: k8s.ovn.org/v1 kind: AdminPolicyBasedExternalRoute metadata: name: shadow-traffic-policy spec: from: namespaceSelector: matchLabels: externalTraffic: "" nextHops: dynamic: - podSelector: matchLabels: gatewayPod: "" namespaceSelector: matchLabels: shadowTraffic: "" networkAttachmentName: shadow-gateway - podSelector: matchLabels: gigabyteGW: "" namespaceSelector: matchLabels: gatewayNamespace: "" networkAttachmentName: gateway
In the following example, the AdminPolicyBasedExternalRoute
object configures both static and dynamic external gateways.
apiVersion: k8s.ovn.org/v1 kind: AdminPolicyBasedExternalRoute metadata: name: multi-hop-policy spec: from: namespaceSelector: matchLabels: trafficType: "egress" nextHops: static: - ip: "172.18.0.8" - ip: "172.18.0.9" dynamic: - podSelector: matchLabels: gatewayPod: "" namespaceSelector: matchLabels: egressTraffic: "" networkAttachmentName: gigabyte
20.7.4. Configure a secondary external gateway
You can configure an external gateway on the default network for a namespace in your cluster.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges.
Procedure
-
Create a YAML file that contains an
AdminPolicyBasedExternalRoute
object. To create an admin policy based external route, enter the following command:
$ oc create -f <file>.yaml
where:
<file>
- Specifies the name of the YAML file that you created in the previous step.
Example output
adminpolicybasedexternalroute.k8s.ovn.org/default-route-policy created
To confirm that the admin policy based external route was created, enter the following command:
$ oc describe apbexternalroute <name> | tail -n 6
where:
<name>
-
Specifies the name of the
AdminPolicyBasedExternalRoute
object.
Example output
Status: Last Transition Time: 2023-04-24T15:09:01Z Messages: Configured external gateway IPs: 172.18.0.8 Status: Success Events: <none>
20.7.5. Additional resources
- For more information about additional network attachments, see Understanding multiple networks
20.8. Configuring an egress IP address
As a cluster administrator, you can configure the OVN-Kubernetes Container Network Interface (CNI) network plugin to assign one or more egress IP addresses to a namespace, or to specific pods in a namespace.
20.8.1. Egress IP address architectural design and implementation
The OpenShift Container Platform egress IP address functionality allows you to ensure that the traffic from one or more pods in one or more namespaces has a consistent source IP address for services outside the cluster network.
For example, you might have a pod that periodically queries a database that is hosted on a server outside of your cluster. To enforce access requirements for the server, a packet filtering device is configured to allow traffic only from specific IP addresses. To ensure that you can reliably allow access to the server from only that specific pod, you can configure a specific egress IP address for the pod that makes the requests to the server.
An egress IP address assigned to a namespace is different from an egress router, which is used to send traffic to specific destinations.
In some cluster configurations, application pods and ingress router pods run on the same node. If you configure an egress IP address for an application project in this scenario, the IP address is not used when you send a request to a route from the application project.
Egress IP addresses must not be configured in any Linux network configuration files, such as ifcfg-eth0
.
20.8.1.1. Platform support
Support for the egress IP address functionality on various platforms is summarized in the following table:
Platform | Supported |
---|---|
Bare metal | Yes |
VMware vSphere | Yes |
Red Hat OpenStack Platform (RHOSP) | Yes |
Amazon Web Services (AWS) | Yes |
Google Cloud Platform (GCP) | Yes |
Microsoft Azure | Yes |
IBM Z® and IBM® LinuxONE | Yes |
IBM Z® and IBM® LinuxONE for Red Hat Enterprise Linux (RHEL) KVM | Yes |
IBM Power® | Yes |
Nutanix | Yes |
The assignment of egress IP addresses to control plane nodes with the EgressIP feature is not supported on a cluster provisioned on Amazon Web Services (AWS). (BZ#2039656).
20.8.1.2. Public cloud platform considerations
For clusters provisioned on public cloud infrastructure, there is a constraint on the absolute number of assignable IP addresses per node. The maximum number of assignable IP addresses per node, or the IP capacity, can be described in the following formula:
IP capacity = public cloud default capacity - sum(current IP assignments)
While the Egress IPs capability manages the IP address capacity per node, it is important to plan for this constraint in your deployments. For example, for a cluster installed on bare-metal infrastructure with 8 nodes you can configure 150 egress IP addresses. However, if a public cloud provider limits IP address capacity to 10 IP addresses per node, the total number of assignable IP addresses is only 80. To achieve the same IP address capacity in this example cloud provider, you would need to allocate 7 additional nodes.
To confirm the IP capacity and subnets for any node in your public cloud environment, you can enter the oc get node <node_name> -o yaml
command. The cloud.network.openshift.io/egress-ipconfig
annotation includes capacity and subnet information for the node.
The annotation value is an array with a single object with fields that provide the following information for the primary network interface:
-
interface
: Specifies the interface ID on AWS and Azure and the interface name on GCP. -
ifaddr
: Specifies the subnet mask for one or both IP address families. -
capacity
: Specifies the IP address capacity for the node. On AWS, the IP address capacity is provided per IP address family. On Azure and GCP, the IP address capacity includes both IPv4 and IPv6 addresses.
Automatic attachment and detachment of egress IP addresses for traffic between nodes are available. This allows for traffic from many pods in namespaces to have a consistent source IP address to locations outside of the cluster.
The RHOSP egress IP address feature creates a Neutron reservation port called egressip-<IP address>
. Using the same RHOSP user as the one used for the OpenShift Container Platform cluster installation, you can assign a floating IP address to this reservation port to have a predictable SNAT address for egress traffic. When an egress IP address on an RHOSP network is moved from one node to another, because of a node failover, for example, the Neutron reservation port is removed and recreated. This means that the floating IP association is lost and you need to manually reassign the floating IP address to the new reservation port.
When an RHOSP cluster administrator assigns a floating IP to the reservation port, OpenShift Container Platform cannot delete the reservation port. The CloudPrivateIPConfig
object cannot perform delete and move operations until an RHOSP cluster administrator unassigns the floating IP from the reservation port.
The following examples illustrate the annotation from nodes on several public cloud providers. The annotations are indented for readability.
Example cloud.network.openshift.io/egress-ipconfig
annotation on AWS
cloud.network.openshift.io/egress-ipconfig: [ { "interface":"eni-078d267045138e436", "ifaddr":{"ipv4":"10.0.128.0/18"}, "capacity":{"ipv4":14,"ipv6":15} } ]
Example cloud.network.openshift.io/egress-ipconfig
annotation on GCP
cloud.network.openshift.io/egress-ipconfig: [ { "interface":"nic0", "ifaddr":{"ipv4":"10.0.128.0/18"}, "capacity":{"ip":14} } ]
The following sections describe the IP address capacity for supported public cloud environments for use in your capacity calculation.
20.8.1.2.1. Amazon Web Services (AWS) IP address capacity limits
On AWS, constraints on IP address assignments depend on the instance type configured. For more information, see IP addresses per network interface per instance type
20.8.1.2.2. Google Cloud Platform (GCP) IP address capacity limits
On GCP, the networking model implements additional node IP addresses through IP address aliasing, rather than IP address assignments. However, IP address capacity maps directly to IP aliasing capacity.
The following capacity limits exist for IP aliasing assignment:
- Per node, the maximum number of IP aliases, both IPv4 and IPv6, is 100.
- Per VPC, the maximum number of IP aliases is unspecified, but OpenShift Container Platform scalability testing reveals the maximum to be approximately 15,000.
For more information, see Per instance quotas and Alias IP ranges overview.
20.8.1.2.3. Microsoft Azure IP address capacity limits
On Azure, the following capacity limits exist for IP address assignment:
- Per NIC, the maximum number of assignable IP addresses, for both IPv4 and IPv6, is 256.
- Per virtual network, the maximum number of assigned IP addresses cannot exceed 65,536.
For more information, see Networking limits.
20.8.1.3. Considerations for using an egress IP on additional network interfaces
In OpenShift Container Platform, egress IPs provide administrators a way to control network traffic. Egress IPs can be used with the br-ex
, or primary, network interface, which is a Linux bridge interface associated with Open vSwitch, or they can be used with additional network interfaces.
You can inspect your network interface type by running the following command:
$ ip -details link show
The primary network interface is assigned a node IP address which also contains a subnet mask. Information for this node IP address can be retrieved from the Kubernetes node object for each node within your cluster by inspecting the k8s.ovn.org/node-primary-ifaddr
annotation. In an IPv4 cluster, this annotation is similar to the following example: "k8s.ovn.org/node-primary-ifaddr: {"ipv4":"192.168.111.23/24"}"
.
If the egress IP is not within the subnet of the primary network interface subnet, you can use an egress IP on another Linux network interface that is not of the primary network interface type. By doing so, OpenShift Container Platform administrators are provided with a greater level of control over networking aspects such as routing, addressing, segmentation, and security policies. This feature provides users with the option to route workload traffic over specific network interfaces for purposes such as traffic segmentation or meeting specialized requirements.
If the egress IP is not within the subnet of the primary network interface, then the selection of another network interface for egress traffic might occur if they are present on a node.
You can determine which other network interfaces might support egress IPs by inspecting the k8s.ovn.org/host-cidrs
Kubernetes node annotation. This annotation contains the addresses and subnet mask found for the primary network interface. It also contains additional network interface addresses and subnet mask information. These addresses and subnet masks are assigned to network interfaces that use the longest prefix match routing mechanism to determine which network interface supports the egress IP.
OVN-Kubernetes provides a mechanism to control and direct outbound network traffic from specific namespaces and pods. This ensures that it exits the cluster through a particular network interface and with a specific egress IP address.
Requirements for assigning an egress IP to a network interface that is not the primary network interface
For users who want an egress IP and traffic to be routed over a particular interface that is not the primary network interface, the following conditions must be met:
- OpenShift Container Platform is installed on a bare metal cluster. This feature is disabled within cloud or hypervisor environments.
- Your OpenShift Container Platform pods are not configured as host-networked.
- If a network interface is removed or if the IP address and subnet mask which allows the egress IP to be hosted on the interface is removed, then the egress IP is reconfigured. Consequently, it could be assigned to another node and interface.
IP forwarding must be enabled for the network interface. To enable IP forwarding, you can use the
oc edit network.operator
command and edit the object like the following example:# ... spec: clusterNetwork: - cidr: 10.128.0.0/14 hostPrefix: 23 defaultNetwork: ovnKubernetesConfig: gatewayConfig: ipForwarding: Global # ...
20.8.1.4. Assignment of egress IPs to pods
To assign one or more egress IPs to a namespace or specific pods in a namespace, the following conditions must be satisfied:
-
At least one node in your cluster must have the
k8s.ovn.org/egress-assignable: ""
label. -
An
EgressIP
object exists that defines one or more egress IP addresses to use as the source IP address for traffic leaving the cluster from pods in a namespace.
If you create EgressIP
objects prior to labeling any nodes in your cluster for egress IP assignment, OpenShift Container Platform might assign every egress IP address to the first node with the k8s.ovn.org/egress-assignable: ""
label.
To ensure that egress IP addresses are widely distributed across nodes in the cluster, always apply the label to the nodes you intent to host the egress IP addresses before creating any EgressIP
objects.
20.8.1.5. Assignment of egress IPs to nodes
When creating an EgressIP
object, the following conditions apply to nodes that are labeled with the k8s.ovn.org/egress-assignable: ""
label:
- An egress IP address is never assigned to more than one node at a time.
- An egress IP address is equally balanced between available nodes that can host the egress IP address.
If the
spec.EgressIPs
array in anEgressIP
object specifies more than one IP address, the following conditions apply:- No node will ever host more than one of the specified IP addresses.
- Traffic is balanced roughly equally between the specified IP addresses for a given namespace.
- If a node becomes unavailable, any egress IP addresses assigned to it are automatically reassigned, subject to the previously described conditions.
When a pod matches the selector for multiple EgressIP
objects, there is no guarantee which of the egress IP addresses that are specified in the EgressIP
objects is assigned as the egress IP address for the pod.
Additionally, if an EgressIP
object specifies multiple egress IP addresses, there is no guarantee which of the egress IP addresses might be used. For example, if a pod matches a selector for an EgressIP
object with two egress IP addresses, 10.10.20.1
and 10.10.20.2
, either might be used for each TCP connection or UDP conversation.
20.8.1.6. Architectural diagram of an egress IP address configuration
The following diagram depicts an egress IP address configuration. The diagram describes four pods in two different namespaces running on three nodes in a cluster. The nodes are assigned IP addresses from the 192.168.126.0/18
CIDR block on the host network.
Both Node 1 and Node 3 are labeled with k8s.ovn.org/egress-assignable: ""
and thus available for the assignment of egress IP addresses.
The dashed lines in the diagram depict the traffic flow from pod1, pod2, and pod3 traveling through the pod network to egress the cluster from Node 1 and Node 3. When an external service receives traffic from any of the pods selected by the example EgressIP
object, the source IP address is either 192.168.126.10
or 192.168.126.102
. The traffic is balanced roughly equally between these two nodes.
The following resources from the diagram are illustrated in detail:
Namespace
objectsThe namespaces are defined in the following manifest:
Namespace objects
apiVersion: v1 kind: Namespace metadata: name: namespace1 labels: env: prod --- apiVersion: v1 kind: Namespace metadata: name: namespace2 labels: env: prod
EgressIP
objectThe following
EgressIP
object describes a configuration that selects all pods in any namespace with theenv
label set toprod
. The egress IP addresses for the selected pods are192.168.126.10
and192.168.126.102
.EgressIP
objectapiVersion: k8s.ovn.org/v1 kind: EgressIP metadata: name: egressips-prod spec: egressIPs: - 192.168.126.10 - 192.168.126.102 namespaceSelector: matchLabels: env: prod status: items: - node: node1 egressIP: 192.168.126.10 - node: node3 egressIP: 192.168.126.102
For the configuration in the previous example, OpenShift Container Platform assigns both egress IP addresses to the available nodes. The
status
field reflects whether and where the egress IP addresses are assigned.
20.8.2. EgressIP object
The following YAML describes the API for the EgressIP
object. The scope of the object is cluster-wide; it is not created in a namespace.
apiVersion: k8s.ovn.org/v1 kind: EgressIP metadata: name: <name> 1 spec: egressIPs: 2 - <ip_address> namespaceSelector: 3 ... podSelector: 4 ...
- 1
- The name for the
EgressIPs
object. - 2
- An array of one or more IP addresses.
- 3
- One or more selectors for the namespaces to associate the egress IP addresses with.
- 4
- Optional: One or more selectors for pods in the specified namespaces to associate egress IP addresses with. Applying these selectors allows for the selection of a subset of pods within a namespace.
The following YAML describes the stanza for the namespace selector:
Namespace selector stanza
namespaceSelector: 1
matchLabels:
<label_name>: <label_value>
- 1
- One or more matching rules for namespaces. If more than one match rule is provided, all matching namespaces are selected.
The following YAML describes the optional stanza for the pod selector:
Pod selector stanza
podSelector: 1
matchLabels:
<label_name>: <label_value>
- 1
- Optional: One or more matching rules for pods in the namespaces that match the specified
namespaceSelector
rules. If specified, only pods that match are selected. Others pods in the namespace are not selected.
In the following example, the EgressIP
object associates the 192.168.126.11
and 192.168.126.102
egress IP addresses with pods that have the app
label set to web
and are in the namespaces that have the env
label set to prod
:
Example EgressIP
object
apiVersion: k8s.ovn.org/v1 kind: EgressIP metadata: name: egress-group1 spec: egressIPs: - 192.168.126.11 - 192.168.126.102 podSelector: matchLabels: app: web namespaceSelector: matchLabels: env: prod
In the following example, the EgressIP
object associates the 192.168.127.30
and 192.168.127.40
egress IP addresses with any pods that do not have the environment
label set to development
:
Example EgressIP
object
apiVersion: k8s.ovn.org/v1 kind: EgressIP metadata: name: egress-group2 spec: egressIPs: - 192.168.127.30 - 192.168.127.40 namespaceSelector: matchExpressions: - key: environment operator: NotIn values: - development
20.8.3. The egressIPConfig object
As a feature of egress IP, the reachabilityTotalTimeoutSeconds
parameter configures the EgressIP node reachability check total timeout in seconds. If the EgressIP node cannot be reached within this timeout, the node is declared down.
You can set a value for the reachabilityTotalTimeoutSeconds
in the configuration file for the egressIPConfig
object. Setting a large value might cause the EgressIP implementation to react slowly to node changes. The implementation reacts slowly for EgressIP nodes that have an issue and are unreachable.
If you omit the reachabilityTotalTimeoutSeconds
parameter from the egressIPConfig
object, the platform chooses a reasonable default value, which is subject to change over time. The current default is 1
second. A value of 0
disables the reachability check for the EgressIP node.
The following egressIPConfig
object describes changing the reachabilityTotalTimeoutSeconds
from the default 1
second probes to 5
second probes:
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: clusterNetwork: - cidr: 10.128.0.0/14 hostPrefix: 23 defaultNetwork: ovnKubernetesConfig: egressIPConfig: 1 reachabilityTotalTimeoutSeconds: 5 2 gatewayConfig: routingViaHost: false genevePort: 6081
- 1
- The
egressIPConfig
holds the configurations for the options of theEgressIP
object. By changing these configurations, you can extend theEgressIP
object. - 2
- The value for
reachabilityTotalTimeoutSeconds
accepts integer values from0
to60
. A value of0
disables the reachability check of the egressIP node. Setting a value from1
to60
corresponds to the timeout in seconds for a probe to send the reachability check to the node.
20.8.4. Labeling a node to host egress IP addresses
You can apply the k8s.ovn.org/egress-assignable=""
label to a node in your cluster so that OpenShift Container Platform can assign one or more egress IP addresses to the node.
Prerequisites
-
Install the OpenShift CLI (
oc
). - Log in to the cluster as a cluster administrator.
Procedure
To label a node so that it can host one or more egress IP addresses, enter the following command:
$ oc label nodes <node_name> k8s.ovn.org/egress-assignable="" 1
- 1
- The name of the node to label.
TipYou can alternatively apply the following YAML to add the label to a node:
apiVersion: v1 kind: Node metadata: labels: k8s.ovn.org/egress-assignable: "" name: <node_name>
20.8.5. Next steps
20.8.6. Additional resources
20.9. Assigning an egress IP address
As a cluster administrator, you can assign an egress IP address for traffic leaving the cluster from a namespace or from specific pods in a namespace.
20.9.1. Assigning an egress IP address to a namespace
You can assign one or more egress IP addresses to a namespace or to specific pods in a namespace.
Prerequisites
-
Install the OpenShift CLI (
oc
). - Log in to the cluster as a cluster administrator.
- Configure at least one node to host an egress IP address.
Procedure
Create an
EgressIP
object:-
Create a
<egressips_name>.yaml
file where<egressips_name>
is the name of the object. In the file that you created, define an
EgressIP
object, as in the following example:apiVersion: k8s.ovn.org/v1 kind: EgressIP metadata: name: egress-project1 spec: egressIPs: - 192.168.127.10 - 192.168.127.11 namespaceSelector: matchLabels: env: qa
-
Create a
To create the object, enter the following command.
$ oc apply -f <egressips_name>.yaml 1
- 1
- Replace
<egressips_name>
with the name of the object.
Example output
egressips.k8s.ovn.org/<egressips_name> created
-
Optional: Store the
<egressips_name>.yaml
file so that you can make changes later. Add labels to the namespace that requires egress IP addresses. To add a label to the namespace of an
EgressIP
object defined in step 1, run the following command:$ oc label ns <namespace> env=qa 1
- 1
- Replace
<namespace>
with the namespace that requires egress IP addresses.
Verification
To show all egress IPs that are in use in your cluster, enter the following command:
$ oc get egressip -o yaml
NoteThe command
oc get egressip
only returns one egress IP address regardless of how many are configured. This is not a bug and is a limitation of Kubernetes. As a workaround, you can pass in the-o yaml
or-o json
flags to return all egress IPs addresses in use.Example output
# ... spec: egressIPs: - 192.168.127.10 - 192.168.127.11 # ...
20.9.2. Additional resources
20.10. Configuring an egress service
As a cluster administrator, you can configure egress traffic for pods behind a load balancer service by using an egress service.
Egress service is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.
For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.
You can use the EgressService
custom resource (CR) to manage egress traffic in the following ways:
Assign a load balancer service IP address as the source IP address for egress traffic for pods behind the load balancer service.
Assigning the load balancer IP address as the source IP address in this context is useful to present a single point of egress and ingress. For example, in some scenarios, an external system communicating with an application behind a load balancer service can expect the source and destination IP address for the application to be the same.
NoteWhen you assign the load balancer service IP address to egress traffic for pods behind the service, OVN-Kubernetes restricts the ingress and egress point to a single node. This limits the load balancing of traffic that MetalLB typically provides.
Assign the egress traffic for pods behind a load balancer to a different network than the default node network.
This is useful to assign the egress traffic for applications behind a load balancer to a different network than the default network. Typically, the different network is implemented by using a VRF instance associated with a network interface.
20.10.1. Egress service custom resource
Define the configuration for an egress service in an EgressService
custom resource. The following YAML describes the fields for the configuration of an egress service:
apiVersion: k8s.ovn.org/v1 kind: EgressService metadata: name: <egress_service_name> 1 namespace: <namespace> 2 spec: sourceIPBy: <egress_traffic_ip> 3 nodeSelector: 4 matchLabels: node-role.kubernetes.io/<role>: "" network: <egress_traffic_network> 5
- 1
- Specify the name for the egress service. The name of the
EgressService
resource must match the name of the load-balancer service that you want to modify. - 2
- Specify the namespace for the egress service. The namespace for the
EgressService
must match the namespace of the load-balancer service that you want to modify. The egress service is namespace-scoped. - 3
- Specify the source IP address of egress traffic for pods behind a service. Valid values are
LoadBalancerIP
orNetwork
. Use theLoadBalancerIP
value to assign theLoadBalancer
service ingress IP address as the source IP address for egress traffic. SpecifyNetwork
to assign the network interface IP address as the source IP address for egress traffic. - 4
- Optional: If you use the
LoadBalancerIP
value for thesourceIPBy
specification, a single node handles theLoadBalancer
service traffic. Use thenodeSelector
field to limit which node can be assigned this task. When a node is selected to handle the service traffic, OVN-Kubernetes labels the node in the following format:egress-service.k8s.ovn.org/<svc-namespace>-<svc-name>: ""
. When thenodeSelector
field is not specified, any node can manage theLoadBalancer
service traffic. - 5
- Optional: Specify the routing table for egress traffic. If you do not include the
network
specification, the egress service uses the default host network.
Example egress service specification
apiVersion: k8s.ovn.org/v1 kind: EgressService metadata: name: test-egress-service namespace: test-namespace spec: sourceIPBy: "LoadBalancerIP" nodeSelector: matchLabels: vrf: "true" network: "2"
20.10.2. Deploying an egress service
You can deploy an egress service to manage egress traffic for pods behind a LoadBalancer
service.
The following example configures the egress traffic to have the same source IP address as the ingress IP address of the LoadBalancer
service.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in as a user with
cluster-admin
privileges. -
You configured MetalLB
BGPPeer
resources.
Procedure
Create an
IPAddressPool
CR with the desired IP for the service:Create a file, such as
ip-addr-pool.yaml
, with content like the following example:apiVersion: metallb.io/v1beta1 kind: IPAddressPool metadata: name: example-pool namespace: metallb-system spec: addresses: - 172.19.0.100/32
Apply the configuration for the IP address pool by running the following command:
$ oc apply -f ip-addr-pool.yaml
Create
Service
andEgressService
CRs:Create a file, such as
service-egress-service.yaml
, with content like the following example:apiVersion: v1 kind: Service metadata: name: example-service namespace: example-namespace annotations: metallb.universe.tf/address-pool: example-pool 1 spec: selector: app: example ports: - name: http protocol: TCP port: 8080 targetPort: 8080 type: LoadBalancer --- apiVersion: k8s.ovn.org/v1 kind: EgressService metadata: name: example-service namespace: example-namespace spec: sourceIPBy: "LoadBalancerIP" 2 nodeSelector: 3 matchLabels: node-role.kubernetes.io/worker: ""
- 1
- The
LoadBalancer
service uses the IP address assigned by MetalLB from theexample-pool
IP address pool. - 2
- This example uses the
LoadBalancerIP
value to assign the ingress IP address of theLoadBalancer
service as the source IP address of egress traffic. - 3
- When you specify the
LoadBalancerIP
value, a single node handles theLoadBalancer
service’s traffic. In this example, only nodes with theworker
label can be selected to handle the traffic. When a node is selected, OVN-Kubernetes labels the node in the following formategress-service.k8s.ovn.org/<svc-namespace>-<svc-name>: ""
.
NoteIf you use the
sourceIPBy: "LoadBalancerIP"
setting, you must specify the load-balancer node in theBGPAdvertisement
custom resource (CR).Apply the configuration for the service and egress service by running the following command:
$ oc apply -f service-egress-service.yaml
Create a
BGPAdvertisement
CR to advertise the service:Create a file, such as
service-bgp-advertisement.yaml
, with content like the following example:apiVersion: metallb.io/v1beta1 kind: BGPAdvertisement metadata: name: example-bgp-adv namespace: metallb-system spec: ipAddressPools: - example-pool nodeSelector: - matchLabels: egress-service.k8s.ovn.org/example-namespace-example-service: "" 1
- 1
- In this example, the
EgressService
CR configures the source IP address for egress traffic to use the load-balancer service IP address. Therefore, you must specify the load-balancer node for return traffic to use the same return path for the traffic originating from the pod.
Verification
Verify that you can access the application endpoint of the pods running behind the MetalLB service by running the following command:
$ curl <external_ip_address>:<port_number> 1
- 1
- Update the external IP address and port number to suit your application endpoint.
-
If you assigned the
LoadBalancer
service’s ingress IP address as the source IP address for egress traffic, verify this configuration by using tools such astcpdump
to analyze packets received at the external client.
20.11. Considerations for the use of an egress router pod
20.11.1. About an egress router pod
The OpenShift Container Platform egress router pod redirects traffic to a specified remote server from a private source IP address that is not used for any other purpose. An egress router pod can send network traffic to servers that are set up to allow access only from specific IP addresses.
The egress router pod is not intended for every outgoing connection. Creating large numbers of egress router pods can exceed the limits of your network hardware. For example, creating an egress router pod for every project or application could exceed the number of local MAC addresses that the network interface can handle before reverting to filtering MAC addresses in software.
The egress router image is not compatible with Amazon AWS, Azure Cloud, or any other cloud platform that does not support layer 2 manipulations due to their incompatibility with macvlan traffic.
20.11.1.1. Egress router modes
In redirect mode, an egress router pod configures iptables
rules to redirect traffic from its own IP address to one or more destination IP addresses. Client pods that need to use the reserved source IP address must be configured to access the service for the egress router rather than connecting directly to the destination IP. You can access the destination service and port from the application pod by using the curl
command. For example:
$ curl <router_service_IP> <port>
The egress router CNI plugin supports redirect mode only. The egress router CNI plugin does not support HTTP proxy mode or DNS proxy mode.
20.11.1.2. Egress router pod implementation
The egress router implementation uses the egress router Container Network Interface (CNI) plugin. The plugin adds a secondary network interface to a pod.
An egress router is a pod that has two network interfaces. For example, the pod can have eth0
and net1
network interfaces. The eth0
interface is on the cluster network and the pod continues to use the interface for ordinary cluster-related network traffic. The net1
interface is on a secondary network and has an IP address and gateway for that network. Other pods in the OpenShift Container Platform cluster can access the egress router service and the service enables the pods to access external services. The egress router acts as a bridge between pods and an external system.
Traffic that leaves the egress router exits through a node, but the packets have the MAC address of the net1
interface from the egress router pod.
When you add an egress router custom resource, the Cluster Network Operator creates the following objects:
-
The network attachment definition for the
net1
secondary network interface of the pod. - A deployment for the egress router.
If you delete an egress router custom resource, the Operator deletes the two objects in the preceding list that are associated with the egress router.
20.11.1.3. Deployment considerations
An egress router pod adds an additional IP address and MAC address to the primary network interface of the node. As a result, you might need to configure your hypervisor or cloud provider to allow the additional address.
- Red Hat OpenStack Platform (RHOSP)
If you deploy OpenShift Container Platform on RHOSP, you must allow traffic from the IP and MAC addresses of the egress router pod on your OpenStack environment. If you do not allow the traffic, then communication will fail:
$ openstack port set --allowed-address \ ip_address=<ip_address>,mac_address=<mac_address> <neutron_port_uuid>
- VMware vSphere
- If you are using VMware vSphere, see the VMware documentation for securing vSphere standard switches. View and change VMware vSphere default settings by selecting the host virtual switch from the vSphere Web Client.
Specifically, ensure that the following are enabled:
20.11.1.4. Failover configuration
To avoid downtime, the Cluster Network Operator deploys the egress router pod as a deployment resource. The deployment name is egress-router-cni-deployment
. The pod that corresponds to the deployment has a label of app=egress-router-cni
.
To create a new service for the deployment, use the oc expose deployment/egress-router-cni-deployment --port <port_number>
command or create a file like the following example:
apiVersion: v1 kind: Service metadata: name: app-egress spec: ports: - name: tcp-8080 protocol: TCP port: 8080 - name: tcp-8443 protocol: TCP port: 8443 - name: udp-80 protocol: UDP port: 80 type: ClusterIP selector: app: egress-router-cni
20.11.2. Additional resources
20.12. Deploying an egress router pod in redirect mode
As a cluster administrator, you can deploy an egress router pod to redirect traffic to specified destination IP addresses from a reserved source IP address.
The egress router implementation uses the egress router Container Network Interface (CNI) plugin.
20.12.1. Egress router custom resource
Define the configuration for an egress router pod in an egress router custom resource. The following YAML describes the fields for the configuration of an egress router in redirect mode:
apiVersion: network.operator.openshift.io/v1 kind: EgressRouter metadata: name: <egress_router_name> namespace: <namespace> 1 spec: addresses: [ 2 { ip: "<egress_router>", 3 gateway: "<egress_gateway>" 4 } ] mode: Redirect redirect: { redirectRules: [ 5 { destinationIP: "<egress_destination>", port: <egress_router_port>, targetPort: <target_port>, 6 protocol: <network_protocol> 7 }, ... ], fallbackIP: "<egress_destination>" 8 }
- 1
- Optional: The
namespace
field specifies the namespace to create the egress router in. If you do not specify a value in the file or on the command line, thedefault
namespace is used. - 2
- The
addresses
field specifies the IP addresses to configure on the secondary network interface. - 3
- The
ip
field specifies the reserved source IP address and netmask from the physical network that the node is on to use with egress router pod. Use CIDR notation to specify the IP address and netmask. - 4
- The
gateway
field specifies the IP address of the network gateway. - 5
- Optional: The
redirectRules
field specifies a combination of egress destination IP address, egress router port, and protocol. Incoming connections to the egress router on the specified port and protocol are routed to the destination IP address. - 6
- Optional: The
targetPort
field specifies the network port on the destination IP address. If this field is not specified, traffic is routed to the same network port that it arrived on. - 7
- The
protocol
field supports TCP, UDP, or SCTP. - 8
- Optional: The
fallbackIP
field specifies a destination IP address. If you do not specify any redirect rules, the egress router sends all traffic to this fallback IP address. If you specify redirect rules, any connections to network ports that are not defined in the rules are sent by the egress router to this fallback IP address. If you do not specify this field, the egress router rejects connections to network ports that are not defined in the rules.
Example egress router specification
apiVersion: network.operator.openshift.io/v1 kind: EgressRouter metadata: name: egress-router-redirect spec: networkInterface: { macvlan: { mode: "Bridge" } } addresses: [ { ip: "192.168.12.99/24", gateway: "192.168.12.1" } ] mode: Redirect redirect: { redirectRules: [ { destinationIP: "10.0.0.99", port: 80, protocol: UDP }, { destinationIP: "203.0.113.26", port: 8080, targetPort: 80, protocol: TCP }, { destinationIP: "203.0.113.27", port: 8443, targetPort: 443, protocol: TCP } ] }
20.12.2. Deploying an egress router in redirect mode
You can deploy an egress router to redirect traffic from its own reserved source IP address to one or more destination IP addresses.
After you add an egress router, the client pods that need to use the reserved source IP address must be modified to connect to the egress router rather than connecting directly to the destination IP.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in as a user with
cluster-admin
privileges.
Procedure
- Create an egress router definition.
To ensure that other pods can find the IP address of the egress router pod, create a service that uses the egress router, as in the following example:
apiVersion: v1 kind: Service metadata: name: egress-1 spec: ports: - name: web-app protocol: TCP port: 8080 type: ClusterIP selector: app: egress-router-cni 1
- 1
- Specify the label for the egress router. The value shown is added by the Cluster Network Operator and is not configurable.
After you create the service, your pods can connect to the service. The egress router pod redirects traffic to the corresponding port on the destination IP address. The connections originate from the reserved source IP address.
Verification
To verify that the Cluster Network Operator started the egress router, complete the following procedure:
View the network attachment definition that the Operator created for the egress router:
$ oc get network-attachment-definition egress-router-cni-nad
The name of the network attachment definition is not configurable.
Example output
NAME AGE egress-router-cni-nad 18m
View the deployment for the egress router pod:
$ oc get deployment egress-router-cni-deployment
The name of the deployment is not configurable.
Example output
NAME READY UP-TO-DATE AVAILABLE AGE egress-router-cni-deployment 1/1 1 1 18m
View the status of the egress router pod:
$ oc get pods -l app=egress-router-cni
Example output
NAME READY STATUS RESTARTS AGE egress-router-cni-deployment-575465c75c-qkq6m 1/1 Running 0 18m
- View the logs and the routing table for the egress router pod.
Get the node name for the egress router pod:
$ POD_NODENAME=$(oc get pod -l app=egress-router-cni -o jsonpath="{.items[0].spec.nodeName}")
Enter into a debug session on the target node. This step instantiates a debug pod called
<node_name>-debug
:$ oc debug node/$POD_NODENAME
Set
/host
as the root directory within the debug shell. The debug pod mounts the root file system of the host in/host
within the pod. By changing the root directory to/host
, you can run binaries from the executable paths of the host:# chroot /host
From within the
chroot
environment console, display the egress router logs:# cat /tmp/egress-router-log
Example output
2021-04-26T12:27:20Z [debug] Called CNI ADD 2021-04-26T12:27:20Z [debug] Gateway: 192.168.12.1 2021-04-26T12:27:20Z [debug] IP Source Addresses: [192.168.12.99/24] 2021-04-26T12:27:20Z [debug] IP Destinations: [80 UDP 10.0.0.99/30 8080 TCP 203.0.113.26/30 80 8443 TCP 203.0.113.27/30 443] 2021-04-26T12:27:20Z [debug] Created macvlan interface 2021-04-26T12:27:20Z [debug] Renamed macvlan to "net1" 2021-04-26T12:27:20Z [debug] Adding route to gateway 192.168.12.1 on macvlan interface 2021-04-26T12:27:20Z [debug] deleted default route {Ifindex: 3 Dst: <nil> Src: <nil> Gw: 10.128.10.1 Flags: [] Table: 254} 2021-04-26T12:27:20Z [debug] Added new default route with gateway 192.168.12.1 2021-04-26T12:27:20Z [debug] Added iptables rule: iptables -t nat PREROUTING -i eth0 -p UDP --dport 80 -j DNAT --to-destination 10.0.0.99 2021-04-26T12:27:20Z [debug] Added iptables rule: iptables -t nat PREROUTING -i eth0 -p TCP --dport 8080 -j DNAT --to-destination 203.0.113.26:80 2021-04-26T12:27:20Z [debug] Added iptables rule: iptables -t nat PREROUTING -i eth0 -p TCP --dport 8443 -j DNAT --to-destination 203.0.113.27:443 2021-04-26T12:27:20Z [debug] Added iptables rule: iptables -t nat -o net1 -j SNAT --to-source 192.168.12.99
The logging file location and logging level are not configurable when you start the egress router by creating an
EgressRouter
object as described in this procedure.From within the
chroot
environment console, get the container ID:# crictl ps --name egress-router-cni-pod | awk '{print $1}'
Example output
CONTAINER bac9fae69ddb6
Determine the process ID of the container. In this example, the container ID is
bac9fae69ddb6
:# crictl inspect -o yaml bac9fae69ddb6 | grep 'pid:' | awk '{print $2}'
Example output
68857
Enter the network namespace of the container:
# nsenter -n -t 68857
Display the routing table:
# ip route
In the following example output, the
net1
network interface is the default route. Traffic for the cluster network uses theeth0
network interface. Traffic for the192.168.12.0/24
network uses thenet1
network interface and originates from the reserved source IP address192.168.12.99
. The pod routes all other traffic to the gateway at IP address192.168.12.1
. Routing for the service network is not shown.Example output
default via 192.168.12.1 dev net1 10.128.10.0/23 dev eth0 proto kernel scope link src 10.128.10.18 192.168.12.0/24 dev net1 proto kernel scope link src 192.168.12.99 192.168.12.1 dev net1
20.13. Enabling multicast for a project
20.13.1. About multicast
With IP multicast, data is broadcast to many IP addresses simultaneously.
- At this time, multicast is best used for low-bandwidth coordination or service discovery and not a high-bandwidth solution.
-
By default, network policies affect all connections in a namespace. However, multicast is unaffected by network policies. If multicast is enabled in the same namespace as your network policies, it is always allowed, even if there is a
deny-all
network policy. Cluster administrators should consider the implications to the exemption of multicast from network policies before enabling it.
Multicast traffic between OpenShift Container Platform pods is disabled by default. If you are using the OVN-Kubernetes network plugin, you can enable multicast on a per-project basis.
20.13.2. Enabling multicast between pods
You can enable multicast between pods for your project.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
You must log in to the cluster with a user that has the
cluster-admin
role.
Procedure
Run the following command to enable multicast for a project. Replace
<namespace>
with the namespace for the project you want to enable multicast for.$ oc annotate namespace <namespace> \ k8s.ovn.org/multicast-enabled=true
TipYou can alternatively apply the following YAML to add the annotation:
apiVersion: v1 kind: Namespace metadata: name: <namespace> annotations: k8s.ovn.org/multicast-enabled: "true"
Verification
To verify that multicast is enabled for a project, complete the following procedure:
Change your current project to the project that you enabled multicast for. Replace
<project>
with the project name.$ oc project <project>
Create a pod to act as a multicast receiver:
$ cat <<EOF| oc create -f - apiVersion: v1 kind: Pod metadata: name: mlistener labels: app: multicast-verify spec: containers: - name: mlistener image: registry.access.redhat.com/ubi9 command: ["/bin/sh", "-c"] args: ["dnf -y install socat hostname && sleep inf"] ports: - containerPort: 30102 name: mlistener protocol: UDP EOF
Create a pod to act as a multicast sender:
$ cat <<EOF| oc create -f - apiVersion: v1 kind: Pod metadata: name: msender labels: app: multicast-verify spec: containers: - name: msender image: registry.access.redhat.com/ubi9 command: ["/bin/sh", "-c"] args: ["dnf -y install socat && sleep inf"] EOF
In a new terminal window or tab, start the multicast listener.
Get the IP address for the Pod:
$ POD_IP=$(oc get pods mlistener -o jsonpath='{.status.podIP}')
Start the multicast listener by entering the following command:
$ oc exec mlistener -i -t -- \ socat UDP4-RECVFROM:30102,ip-add-membership=224.1.0.1:$POD_IP,fork EXEC:hostname
Start the multicast transmitter.
Get the pod network IP address range:
$ CIDR=$(oc get Network.config.openshift.io cluster \ -o jsonpath='{.status.clusterNetwork[0].cidr}')
To send a multicast message, enter the following command:
$ oc exec msender -i -t -- \ /bin/bash -c "echo | socat STDIO UDP4-DATAGRAM:224.1.0.1:30102,range=$CIDR,ip-multicast-ttl=64"
If multicast is working, the previous command returns the following output:
mlistener
20.14. Disabling multicast for a project
20.14.1. Disabling multicast between pods
You can disable multicast between pods for your project.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
You must log in to the cluster with a user that has the
cluster-admin
role.
Procedure
Disable multicast by running the following command:
$ oc annotate namespace <namespace> \ 1 k8s.ovn.org/multicast-enabled-
- 1
- The
namespace
for the project you want to disable multicast for.
TipYou can alternatively apply the following YAML to delete the annotation:
apiVersion: v1 kind: Namespace metadata: name: <namespace> annotations: k8s.ovn.org/multicast-enabled: null
20.15. Tracking network flows
As a cluster administrator, you can collect information about pod network flows from your cluster to assist with the following areas:
- Monitor ingress and egress traffic on the pod network.
- Troubleshoot performance issues.
- Gather data for capacity planning and security audits.
When you enable the collection of the network flows, only the metadata about the traffic is collected. For example, packet data is not collected, but the protocol, source address, destination address, port numbers, number of bytes, and other packet-level information is collected.
The data is collected in one or more of the following record formats:
- NetFlow
- sFlow
- IPFIX
When you configure the Cluster Network Operator (CNO) with one or more collector IP addresses and port numbers, the Operator configures Open vSwitch (OVS) on each node to send the network flows records to each collector.
You can configure the Operator to send records to more than one type of network flow collector. For example, you can send records to NetFlow collectors and also send records to sFlow collectors.
When OVS sends data to the collectors, each type of collector receives identical records. For example, if you configure two NetFlow collectors, OVS on a node sends identical records to the two collectors. If you also configure two sFlow collectors, the two sFlow collectors receive identical records. However, each collector type has a unique record format.
Collecting the network flows data and sending the records to collectors affects performance. Nodes process packets at a slower rate. If the performance impact is too great, you can delete the destinations for collectors to disable collecting network flows data and restore performance.
Enabling network flow collectors might have an impact on the overall performance of the cluster network.
20.15.1. Network object configuration for tracking network flows
The fields for configuring network flows collectors in the Cluster Network Operator (CNO) are shown in the following table:
Field | Type | Description |
---|---|---|
|
|
The name of the CNO object. This name is always |
|
|
One or more of |
|
| A list of IP address and network port pairs for up to 10 collectors. |
|
| A list of IP address and network port pairs for up to 10 collectors. |
|
| A list of IP address and network port pairs for up to 10 collectors. |
After applying the following manifest to the CNO, the Operator configures Open vSwitch (OVS) on each node in the cluster to send network flows records to the NetFlow collector that is listening at 192.168.1.99:2056
.
Example configuration for tracking network flows
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: exportNetworkFlows: netFlow: collectors: - 192.168.1.99:2056
20.15.2. Adding destinations for network flows collectors
As a cluster administrator, you can configure the Cluster Network Operator (CNO) to send network flows metadata about the pod network to a network flows collector.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges. - You have a network flows collector and know the IP address and port that it listens on.
Procedure
Create a patch file that specifies the network flows collector type and the IP address and port information of the collectors:
spec: exportNetworkFlows: netFlow: collectors: - 192.168.1.99:2056
Configure the CNO with the network flows collectors:
$ oc patch network.operator cluster --type merge -p "$(cat <file_name>.yaml)"
Example output
network.operator.openshift.io/cluster patched
Verification
Verification is not typically necessary. You can run the following command to confirm that Open vSwitch (OVS) on each node is configured to send network flows records to one or more collectors.
View the Operator configuration to confirm that the
exportNetworkFlows
field is configured:$ oc get network.operator cluster -o jsonpath="{.spec.exportNetworkFlows}"
Example output
{"netFlow":{"collectors":["192.168.1.99:2056"]}}
View the network flows configuration in OVS from each node:
$ for pod in $(oc get pods -n openshift-ovn-kubernetes -l app=ovnkube-node -o jsonpath='{range@.items[*]}{.metadata.name}{"\n"}{end}'); do ; echo; echo $pod; oc -n openshift-ovn-kubernetes exec -c ovnkube-controller $pod \ -- bash -c 'for type in ipfix sflow netflow ; do ovs-vsctl find $type ; done'; done
Example output
ovnkube-node-xrn4p _uuid : a4d2aaca-5023-4f3d-9400-7275f92611f9 active_timeout : 60 add_id_to_interface : false engine_id : [] engine_type : [] external_ids : {} targets : ["192.168.1.99:2056"] ovnkube-node-z4vq9 _uuid : 61d02fdb-9228-4993-8ff5-b27f01a29bd6 active_timeout : 60 add_id_to_interface : false engine_id : [] engine_type : [] external_ids : {} targets : ["192.168.1.99:2056"]- ...
20.15.3. Deleting all destinations for network flows collectors
As a cluster administrator, you can configure the Cluster Network Operator (CNO) to stop sending network flows metadata to a network flows collector.
Prerequisites
-
You installed the OpenShift CLI (
oc
). -
You are logged in to the cluster with a user with
cluster-admin
privileges.
Procedure
Remove all network flows collectors:
$ oc patch network.operator cluster --type='json' \ -p='[{"op":"remove", "path":"/spec/exportNetworkFlows"}]'
Example output
network.operator.openshift.io/cluster patched
20.15.4. Additional resources
20.16. Configuring hybrid networking
As a cluster administrator, you can configure the Red Hat OpenShift Networking OVN-Kubernetes network plugin to allow Linux and Windows nodes to host Linux and Windows workloads, respectively.
20.16.1. Configuring hybrid networking with OVN-Kubernetes
You can configure your cluster to use hybrid networking with the OVN-Kubernetes network plugin. This allows a hybrid cluster that supports different node networking configurations.
This configuration is necessary to run both Linux and Windows nodes in the same cluster.
Prerequisites
-
Install the OpenShift CLI (
oc
). -
Log in to the cluster as a user with
cluster-admin
privileges. - Ensure that the cluster uses the OVN-Kubernetes network plugin.
Procedure
To configure the OVN-Kubernetes hybrid network overlay, enter the following command:
$ oc patch networks.operator.openshift.io cluster --type=merge \ -p '{ "spec":{ "defaultNetwork":{ "ovnKubernetesConfig":{ "hybridOverlayConfig":{ "hybridClusterNetwork":[ { "cidr": "<cidr>", "hostPrefix": <prefix> } ], "hybridOverlayVXLANPort": <overlay_port> } } } } }'
where:
cidr
- Specify the CIDR configuration used for nodes on the additional overlay network. This CIDR must not overlap with the cluster network CIDR.
hostPrefix
-
Specifies the subnet prefix length to assign to each individual node. For example, if
hostPrefix
is set to23
, then each node is assigned a/23
subnet out of the givencidr
, which allows for 510 (2^(32 - 23) - 2) pod IP addresses. If you are required to provide access to nodes from an external network, configure load balancers and routers to manage the traffic. hybridOverlayVXLANPort
-
Specify a custom VXLAN port for the additional overlay network. This is required for running Windows nodes in a cluster installed on vSphere, and must not be configured for any other cloud provider. The custom port can be any open port excluding the default
4789
port. For more information on this requirement, see the Microsoft documentation on Pod-to-pod connectivity between hosts is broken.
Example output
network.operator.openshift.io/cluster patched
To confirm that the configuration is active, enter the following command. It can take several minutes for the update to apply.
$ oc get network.operator.openshift.io -o jsonpath="{.items[0].spec.defaultNetwork.ovnKubernetesConfig}"