Chapter 11. Node networking
11.1. Observing node network state
Node network state is the network configuration for all nodes in the cluster.
11.1.1. About nmstate
OpenShift Virtualization uses nmstate
to report on and configure the state of the node network. This makes it possible to modify network policy configuration, such as by creating a Linux bridge on all nodes, by applying a single configuration manifest to the cluster.
Node networking is monitored and updated by the following objects:
NodeNetworkState
- Reports the state of the network on that node.
NodeNetworkConfigurationPolicy
-
Describes the requested network configuration on nodes. You update the node network configuration, including adding and removing interfaces, by applying a
NodeNetworkConfigurationPolicy
manifest to the cluster. NodeNetworkConfigurationEnactment
- Reports the network policies enacted upon each node.
OpenShift Virtualization supports the use of the following nmstate interface types:
- Linux Bridge
- VLAN
- Bond
- Ethernet
If your OpenShift Container Platform cluster uses OVN-Kubernetes as the default Container Network Interface (CNI) provider, you cannot attach a Linux bridge or bonding to the default interface of a host because of a change in the host network topology of OVN-Kubernetes. As a workaround, you can use a secondary network interface connected to your host, or switch to the OpenShift SDN default CNI provider.
11.1.2. Viewing the network state of a node
A NodeNetworkState
object exists on every node in the cluster. This object is periodically updated and captures the state of the network for that node.
Procedure
List all the
NodeNetworkState
objects in the cluster:$ oc get nns
Inspect a
NodeNetworkState
object to view the network on that node. The output in this example has been redacted for clarity:$ oc get nns node01 -o yaml
Example output
apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkState metadata: name: node01 1 status: currentState: 2 dns-resolver: ... interfaces: ... route-rules: ... routes: ... lastSuccessfulUpdateTime: "2020-01-31T12:14:00Z" 3
- 1
- The name of the
NodeNetworkState
object is taken from the node. - 2
- The
currentState
contains the complete network configuration for the node, including DNS, interfaces, and routes. - 3
- Timestamp of the last successful update. This is updated periodically as long as the node is reachable and can be used to evalute the freshness of the report.
11.2. Updating node network configuration
You can update the node network configuration, such as adding or removing interfaces from nodes, by applying NodeNetworkConfigurationPolicy
manifests to the cluster.
11.2.1. About nmstate
OpenShift Virtualization uses nmstate
to report on and configure the state of the node network. This makes it possible to modify network policy configuration, such as by creating a Linux bridge on all nodes, by applying a single configuration manifest to the cluster.
Node networking is monitored and updated by the following objects:
NodeNetworkState
- Reports the state of the network on that node.
NodeNetworkConfigurationPolicy
-
Describes the requested network configuration on nodes. You update the node network configuration, including adding and removing interfaces, by applying a
NodeNetworkConfigurationPolicy
manifest to the cluster. NodeNetworkConfigurationEnactment
- Reports the network policies enacted upon each node.
OpenShift Virtualization supports the use of the following nmstate interface types:
- Linux Bridge
- VLAN
- Bond
- Ethernet
If your OpenShift Container Platform cluster uses OVN-Kubernetes as the default Container Network Interface (CNI) provider, you cannot attach a Linux bridge or bonding to the default interface of a host because of a change in the host network topology of OVN-Kubernetes. As a workaround, you can use a secondary network interface connected to your host, or switch to the OpenShift SDN default CNI provider.
11.2.2. Creating an interface on nodes
Create an interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy
manifest to the cluster. The manifest details the requested configuration for the interface.
By default, the manifest applies to all nodes in the cluster. To add the interface to specific nodes, add the spec: nodeSelector
parameter and the appropriate <key>:<value>
for your node selector.
Procedure
Create the
NodeNetworkConfigurationPolicy
manifest. The following example configures a Linux bridge on all worker nodes:apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: <br1-eth1-policy> 1 spec: nodeSelector: 2 node-role.kubernetes.io/worker: "" 3 desiredState: interfaces: - name: br1 description: Linux bridge with eth1 as a port 4 type: linux-bridge state: up ipv4: dhcp: true enabled: true bridge: options: stp: enabled: false port: - name: eth1
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses the
node-role.kubernetes.io/worker: ""
node selector to select all worker nodes in the cluster. - 4
- Optional: Human-readable description for the interface.
Create the node network policy:
$ oc apply -f <br1-eth1-policy.yaml> 1
- 1
- File name of the node network configuration policy manifest.
Additional resources
11.2.3. Confirming node network policy updates on nodes
A NodeNetworkConfigurationPolicy
manifest describes your requested network configuration for nodes in the cluster. The node network policy includes your requested network configuration and the status of execution of the policy on the cluster as a whole.
When you apply a node network policy, a NodeNetworkConfigurationEnactment
object is created for every node in the cluster. The node network configuration enactment is a read-only object that represents the status of execution of the policy on that node. If the policy fails to be applied on the node, the enactment for that node includes a traceback for troubleshooting.
Procedure
To confirm that a policy has been applied to the cluster, list the policies and their status:
$ oc get nncp
Optional: If a policy is taking longer than expected to successfully configure, you can inspect the requested state and status conditions of a particular policy:
$ oc get nncp <policy> -o yaml
Optional: If a policy is taking longer than expected to successfully configure on all nodes, you can list the status of the enactments on the cluster:
$ oc get nnce
Optional: To view the configuration of a particular enactment, including any error reporting for a failed configuration:
$ oc get nnce <node>.<policy> -o yaml
11.2.4. Removing an interface from nodes
You can remove an interface from one or more nodes in the cluster by editing the NodeNetworkConfigurationPolicy
object and setting the state
of the interface to absent
.
Removing an interface from a node does not automatically restore the node network configuration to a previous state. If you want to restore the previous state, you will need to define that node network configuration in the policy.
If you remove a bridge or bonding interface, any node NICs in the cluster that were previously attached or subordinate to that bridge or bonding interface are placed in a down
state and become unreachable. To avoid losing connectivity, configure the node NIC in the same policy so that it has a status of up
and either DHCP or a static IP address.
Deleting the node network policy that added an interface does not change the configuration of the policy on the node. Although a NodeNetworkConfigurationPolicy
is an object in the cluster, it only represents the requested configuration.
Similarly, removing an interface does not delete the policy.
Procedure
Update the
NodeNetworkConfigurationPolicy
manifest used to create the interface. The following example removes a Linux bridge and configures theeth1
NIC with DHCP to avoid losing connectivity:apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: <br1-eth1-policy> 1 spec: nodeSelector: 2 node-role.kubernetes.io/worker: "" 3 desiredState: interfaces: - name: br1 type: linux-bridge state: absent 4 - name: eth1 5 type: ethernet 6 state: up 7 ipv4: dhcp: true 8 enabled: true 9
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses the
node-role.kubernetes.io/worker: ""
node selector to select all worker nodes in the cluster. - 4
- Changing the state to
absent
removes the interface. - 5
- The name of the interface that is to be unattached from the bridge interface.
- 6
- The type of interface. This example creates an Ethernet networking interface.
- 7
- The requested state for the interface.
- 8
- Optional: If you do not use
dhcp
, you can either set a static IP or leave the interface without an IP address. - 9
- Enables
ipv4
in this example.
Update the policy on the node and remove the interface:
$ oc apply -f <br1-eth1-policy.yaml> 1
- 1
- File name of the policy manifest.
11.2.5. Example policy configurations for different interfaces
11.2.5.1. Example: Linux bridge interface node network configuration policy
Create a Linux bridge interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy
manifest to the cluster.
The following YAML file is an example of a manifest for a Linux bridge interface. It includes samples values that you must replace with your own information.
apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: br1-eth1-policy 1 spec: nodeSelector: 2 kubernetes.io/hostname: <node01> 3 desiredState: interfaces: - name: br1 4 description: Linux bridge with eth1 as a port 5 type: linux-bridge 6 state: up 7 ipv4: dhcp: true 8 enabled: true 9 bridge: options: stp: enabled: false 10 port: - name: eth1 11
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses a
hostname
node selector. - 4
- Name of the interface.
- 5
- Optional: Human-readable description of the interface.
- 6
- The type of interface. This example creates a bridge.
- 7
- The requested state for the interface after creation.
- 8
- Optional: If you do not use
dhcp
, you can either set a static IP or leave the interface without an IP address. - 9
- Enables
ipv4
in this example. - 10
- Disables
stp
in this example. - 11
- The node NIC to which the bridge attaches.
11.2.5.2. Example: VLAN interface node network configuration policy
Create a VLAN interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy
manifest to the cluster.
The following YAML file is an example of a manifest for a VLAN interface. It includes samples values that you must replace with your own information.
apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: vlan-eth1-policy 1 spec: nodeSelector: 2 kubernetes.io/hostname: <node01> 3 desiredState: interfaces: - name: eth1.102 4 description: VLAN using eth1 5 type: vlan 6 state: up 7 vlan: base-iface: eth1 8 id: 102 9
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses a
hostname
node selector. - 4
- Name of the interface.
- 5
- Optional: Human-readable description of the interface.
- 6
- The type of interface. This example creates a VLAN.
- 7
- The requested state for the interface after creation.
- 8
- The node NIC to which the VLAN is attached.
- 9
- The VLAN tag.
11.2.5.3. Example: Bond interface node network configuration policy
Create a bond interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy
manifest to the cluster.
OpenShift Virtualization only supports the following bond modes:
-
mode=1 active-backup
-
mode=2 balance-xor
-
mode=4 802.3ad
-
mode=5 balance-tlb
- mode=6 balance-alb
The following YAML file is an example of a manifest for a bond interface. It includes samples values that you must replace with your own information.
apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: bond0-eth1-eth2-policy 1 spec: nodeSelector: 2 kubernetes.io/hostname: <node01> 3 desiredState: interfaces: - name: bond0 4 description: Bond enslaving eth1 and eth2 5 type: bond 6 state: up 7 ipv4: dhcp: true 8 enabled: true 9 link-aggregation: mode: active-backup 10 options: miimon: '140' 11 slaves: 12 - eth1 - eth2 mtu: 1450 13
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses a
hostname
node selector. - 4
- Name of the interface.
- 5
- Optional: Human-readable description of the interface.
- 6
- The type of interface. This example creates a bond.
- 7
- The requested state for the interface after creation.
- 8
- Optional: If you do not use
dhcp
, you can either set a static IP or leave the interface without an IP address. - 9
- Enables
ipv4
in this example. - 10
- The driver mode for the bond. This example uses an active backup mode.
- 11
- Optional: This example uses miimon to inspect the bond link every 140ms.
- 12
- The subordinate node NICs in the bond.
- 13
- Optional: The maximum transmission unit (MTU) for the bond. If not specified, this value is set to
1500
by default.
11.2.5.4. Example: Ethernet interface node network configuration policy
Configure an Ethernet interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy
manifest to the cluster.
The following YAML file is an example of a manifest for an Ethernet interface. It includes sample values that you must replace with your own information.
apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: eth1-policy 1 spec: nodeSelector: 2 kubernetes.io/hostname: <node01> 3 desiredState: interfaces: - name: eth1 4 description: Configuring eth1 on node01 5 type: ethernet 6 state: up 7 ipv4: dhcp: true 8 enabled: true 9
- 1
- Name of the policy.
- 2
- Optional: If you do not include the
nodeSelector
parameter, the policy applies to all nodes in the cluster. - 3
- This example uses a
hostname
node selector. - 4
- Name of the interface.
- 5
- Optional: Human-readable description of the interface.
- 6
- The type of interface. This example creates an Ethernet networking interface.
- 7
- The requested state for the interface after creation.
- 8
- Optional: If you do not use
dhcp
, you can either set a static IP or leave the interface without an IP address. - 9
- Enables
ipv4
in this example.
11.2.5.5. Example: Multiple interfaces in the same node network configuration policy
You can create multiple interfaces in the same node network configuration policy. These interfaces can reference each other, allowing you to build and deploy a network configuration by using a single policy manifest.
The following example snippet creates a bond that is named bond10
across two NICs and a Linux bridge that is named br1
that connects to the bond.
... interfaces: - name: bond10 description: Bonding eth2 and eth3 for Linux bridge type: bond state: up link-aggregation: slaves: - eth2 - eth3 - name: br1 description: Linux bridge on bond type: linux-bridge state: up bridge: port: - name: bond10 ...
11.2.6. Examples: IP management
The following example configuration snippets demonstrate different methods of IP management.
These examples use the ethernet
interface type to simplify the example while showing the related context in the policy configuration. These IP management examples can be used with the other interface types.
11.2.6.1. Static
The following snippet statically configures an IP address on the Ethernet interface:
...
interfaces:
- name: eth1
description: static IP on eth1
type: ethernet
state: up
ipv4:
address:
- ip: 192.168.122.250 1
prefix-length: 24
enabled: true
...
- 1
- Replace this value with the static IP address for the interface.
11.2.6.2. No IP address
The following snippet ensures that the interface has no IP address:
... interfaces: - name: eth1 description: No IP on eth1 type: ethernet state: up ipv4: enabled: false ...
11.2.6.3. Dynamic host configuration
The following snippet configures an Ethernet interface that uses a dynamic IP address, gateway address, and DNS:
... interfaces: - name: eth1 description: DHCP on eth1 type: ethernet state: up ipv4: dhcp: true enabled: true ...
The following snippet configures an Ethernet interface that uses a dynamic IP address but does not use a dynamic gateway address or DNS:
... interfaces: - name: eth1 description: DHCP without gateway or DNS on eth1 type: ethernet state: up ipv4: dhcp: true auto-gateway: false auto-dns: false enabled: true ...
11.2.6.4. DNS
The following snippet sets DNS configuration on the host.
... interfaces: ... dns-resolver: config: search: - example.com - example.org server: - 8.8.8.8 ...
11.2.6.5. Static routing
The following snippet configures a static route and a static IP on interface eth1
.
... interfaces: - name: eth1 description: Static routing on eth1 type: ethernet state: up ipv4: address: - ip: 192.0.2.251 1 prefix-length: 24 enabled: true routes: config: - destination: 198.51.100.0/24 metric: 150 next-hop-address: 192.0.2.1 2 next-hop-interface: eth1 table-id: 254 ...
11.3. Troubleshooting node network configuration
If the node network configuration encounters an issue, the policy is automatically rolled back and the enactments report failure. This includes issues such as:
- The configuration fails to be applied on the host.
- The host loses connection to the default gateway.
- The host loses connection to the API server.
11.3.1. Troubleshooting an incorrect node network configuration policy configuration
You can apply changes to the node network configuration across your entire cluster by applying a node network configuration policy. If you apply an incorrect configuration, you can use the following example to troubleshoot and correct the failed node network policy.
In this example, a Linux bridge policy is applied to an example cluster that has 3 master nodes and 3 worker nodes. The policy fails to be applied because it references an incorrect interface. To find the error, investigate the available nmstate resources. You can then update the policy with the correct configuration.
Procedure
Create a policy and apply it to your cluster. The following example creates a simple bridge on the
ens01
interface:apiVersion: nmstate.io/v1alpha1 kind: NodeNetworkConfigurationPolicy metadata: name: ens01-bridge-testfail spec: desiredState: interfaces: - name: br1 description: Linux bridge with the wrong port type: linux-bridge state: up ipv4: dhcp: true enabled: true bridge: options: stp: enabled: false port: - name: ens01
$ oc apply -f ens01-bridge-testfail.yaml
Example output
nodenetworkconfigurationpolicy.nmstate.io/ens01-bridge-testfail created
Verify the status of the policy by running the following command:
$ oc get nncp
The output shows that the policy failed:
Example output
NAME STATUS ens01-bridge-testfail FailedToConfigure
However, the policy status alone does not indicate if it failed on all nodes or a subset of nodes.
List the node network configuration enactments to see if the policy was successful on any of the nodes. If the policy failed for only a subset of nodes, it suggests that the problem is with a specific node configuration. If the policy failed on all nodes, it suggests that the problem is with the policy.
$ oc get nnce
The output shows that the policy failed on all nodes:
Example output
NAME STATUS master-1.ens01-bridge-testfail FailedToConfigure master-2.ens01-bridge-testfail FailedToConfigure master-3.ens01-bridge-testfail FailedToConfigure worker-1.ens01-bridge-testfail FailedToConfigure worker-2.ens01-bridge-testfail FailedToConfigure worker-3.ens01-bridge-testfail FailedToConfigure
View one of the failed enactments and look at the traceback. The following command uses the output tool
jsonpath
to filter the output:$ oc get nnce worker-1.ens01-bridge-testfail -o jsonpath='{.status.conditions[?(@.type=="Failing")].message}'
This command returns a large traceback that has been edited for brevity:
Example output
error reconciling NodeNetworkConfigurationPolicy at desired state apply: , failed to execute nmstatectl set --no-commit --timeout 480: 'exit status 1' '' ... libnmstate.error.NmstateVerificationError: desired ======= --- name: br1 type: linux-bridge state: up bridge: options: group-forward-mask: 0 mac-ageing-time: 300 multicast-snooping: true stp: enabled: false forward-delay: 15 hello-time: 2 max-age: 20 priority: 32768 port: - name: ens01 description: Linux bridge with the wrong port ipv4: address: [] auto-dns: true auto-gateway: true auto-routes: true dhcp: true enabled: true ipv6: enabled: false mac-address: 01-23-45-67-89-AB mtu: 1500 current ======= --- name: br1 type: linux-bridge state: up bridge: options: group-forward-mask: 0 mac-ageing-time: 300 multicast-snooping: true stp: enabled: false forward-delay: 15 hello-time: 2 max-age: 20 priority: 32768 port: [] description: Linux bridge with the wrong port ipv4: address: [] auto-dns: true auto-gateway: true auto-routes: true dhcp: true enabled: true ipv6: enabled: false mac-address: 01-23-45-67-89-AB mtu: 1500 difference ========== --- desired +++ current @@ -13,8 +13,7 @@ hello-time: 2 max-age: 20 priority: 32768 - port: - - name: ens01 + port: [] description: Linux bridge with the wrong port ipv4: address: [] line 651, in _assert_interfaces_equal\n current_state.interfaces[ifname],\nlibnmstate.error.NmstateVerificationError:
The
NmstateVerificationError
lists thedesired
policy configuration, thecurrent
configuration of the policy on the node, and thedifference
highlighting the parameters that do not match. In this example, theport
is included in thedifference
, which suggests that the problem is the port configuration in the policy.To ensure that the policy is configured properly, view the network configuration for one or all of the nodes by requesting the
NodeNetworkState
object. The following command returns the network configuration for themaster-1
node:$ oc get nns master-1 -o yaml
The output shows that the interface name on the nodes is
ens1
but the failed policy incorrectly usesens01
:Example output
- ipv4: ... name: ens1 state: up type: ethernet
Correct the error by editing the existing policy:
$ oc edit nncp ens01-bridge-testfail
... port: - name: ens1
Save the policy to apply the correction.
Check the status of the policy to ensure it updated successfully:
$ oc get nncp
Example output
NAME STATUS ens01-bridge-testfail SuccessfullyConfigured
The updated policy is successfully configured on all nodes in the cluster.