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Chapter 29. Kubernetes NMState

29.1. About the Kubernetes NMState Operator

The Kubernetes NMState Operator provides a Kubernetes API for performing state-driven network configuration across the OpenShift Container Platform cluster’s nodes with NMState. The Kubernetes NMState Operator provides users with functionality to configure various network interface types, DNS, and routing on cluster nodes. Additionally, the daemons on the cluster nodes periodically report on the state of each node’s network interfaces to the API server.

Important

Red Hat supports the Kubernetes NMState Operator in production environments on bare-metal, IBM Power, IBM Z, IBM® LinuxONE, VMware vSphere, and OpenStack installations.

Before you can use NMState with OpenShift Container Platform, you must install the Kubernetes NMState Operator.

Note

The Kubernetes NMState Operator updates the network configuration of a secondary NIC. It cannot update the network configuration of the primary NIC or the br-ex bridge.

OpenShift Container Platform uses nmstate to report on and configure the state of the node network. This makes it possible to modify the 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.

29.1.1. Installing the Kubernetes NMState Operator

You can install the Kubernetes NMState Operator by using the web console or the CLI.

29.1.1.1. Installing the Kubernetes NMState Operator using the web console

You can install the Kubernetes NMState Operator by using the web console. After it is installed, the Operator can deploy the NMState State Controller as a daemon set across all of the cluster nodes.

Prerequisites

  • You are logged in as a user with cluster-admin privileges.

Procedure

  1. Select Operators OperatorHub.
  2. In the search field below All Items, enter nmstate and click Enter to search for the Kubernetes NMState Operator.
  3. Click on the Kubernetes NMState Operator search result.
  4. Click on Install to open the Install Operator window.
  5. Click Install to install the Operator.
  6. After the Operator finishes installing, click View Operator.
  7. Under Provided APIs, click Create Instance to open the dialog box for creating an instance of kubernetes-nmstate.

  8. In the Name field of the dialog box, ensure the name of the instance is nmstate.

    Note

    The name restriction is a known issue. The instance is a singleton for the entire cluster.

  9. Accept the default settings and click Create to create the instance.

Summary

Once complete, the Operator has deployed the NMState State Controller as a daemon set across all of the cluster nodes.

29.1.1.2. Installing the Kubernetes NMState Operator using the CLI

You can install the Kubernetes NMState Operator by using the OpenShift CLI (oc). After it is installed, the Operator can deploy the NMState State Controller as a daemon set across all of the cluster nodes.

Prerequisites

  • You have installed the OpenShift CLI (oc).
  • You are logged in as a user with cluster-admin privileges.

Procedure

  1. Create the nmstate Operator namespace: 

    $ cat << EOF | oc apply -f -
apiVersion: v1
kind: Namespace
metadata:
  name: openshift-nmstate
spec:
  finalizers:
  - kubernetes
EOF

  2. Create the OperatorGroup: 

    $ cat << EOF | oc apply -f -
apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: openshift-nmstate
  namespace: openshift-nmstate
spec:
  targetNamespaces:
  - openshift-nmstate
EOF

  3. Subscribe to the nmstate Operator: 

    $ cat << EOF| oc apply -f -
apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: kubernetes-nmstate-operator
  namespace: openshift-nmstate
spec:
  channel: stable
  installPlanApproval: Automatic
  name: kubernetes-nmstate-operator
  source: redhat-operators
  sourceNamespace: openshift-marketplace
EOF

  4. Create instance of the nmstate operator: 

    $ cat << EOF | oc apply -f -
apiVersion: nmstate.io/v1
kind: NMState
metadata:
  name: nmstate
EOF

Verification

  • Confirm that the deployment for the nmstate operator is running: 

    oc get clusterserviceversion -n openshift-nmstate \
 -o custom-columns=Name:.metadata.name,Phase:.status.phase

    Example output

    Name                                             Phase
kubernetes-nmstate-operator.4.13.0-202210210157   Succeeded

29.2. Observing and updating the node network state and configuration

29.2.1. Viewing the network state of a node

Node network state is the network configuration for all nodes in the cluster. 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

  1. List all the NodeNetworkState objects in the cluster: 

    $ oc get nns

  2. 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/v1
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.

29.2.2. Managing policy by using the CLI

29.2.2.1. 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.

You can configure multiple nmstate-enabled nodes concurrently. The configuration applies to 50% of the nodes in parallel. This strategy prevents the entire cluster from being unavailable if the network connection fails. To apply the policy configuration in parallel to a specific portion of the cluster, use the maxUnavailable field.

Procedure

  1. Create the NodeNetworkConfigurationPolicy manifest. The following example configures a Linux bridge on all worker nodes and configures the DNS resolver: 

    apiVersion: nmstate.io/v1
kind: NodeNetworkConfigurationPolicy
metadata:
  name: br1-eth1-policy 1
spec:
  nodeSelector: 2
    node-role.kubernetes.io/worker: "" 3
  maxUnavailable: 3 4
  desiredState:
    interfaces:
      - name: br1
        description: Linux bridge with eth1 as a port 5
        type: linux-bridge
        state: up
        ipv4:
          dhcp: true
          enabled: true
          auto-dns: false
        bridge:
          options:
            stp:
              enabled: false
          port:
            - name: eth1
    dns-resolver: 6
      config:
        search:
        - example.com
        - example.org
        server:
        - 8.8.8.8
    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: Specifies the maximum number of nmstate-enabled nodes that the policy configuration can be applied to concurrently. This parameter can be set to either a percentage value (string), for example, "10%", or an absolute value (number), such as 3.
    5
    Optional: Human-readable description for the interface.
    6
    Optional: Specifies the search and server settings for the DNS server.

  2. 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

29.2.3. 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

  1. To confirm that a policy has been applied to the cluster, list the policies and their status: 

    $ oc get nncp

  2. 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

  3. 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

  4. Optional: To view the configuration of a particular enactment, including any error reporting for a failed configuration: 

    $ oc get nnce <node>.<policy> -o yaml

29.2.4. 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.

Note

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

  1. Update the NodeNetworkConfigurationPolicy manifest used to create the interface. The following example removes a Linux bridge and configures the eth1 NIC with DHCP to avoid losing connectivity: 

    apiVersion: nmstate.io/v1
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.

  2. 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.

29.2.5. Example policy configurations for different interfaces

Before you read the different example NodeNetworkConfigurationPolicy (NNCP) manifest configurations, consider the following factors when you apply a policy so that your cluster runs at its best performance conditions:

  • When you need to apply a policy to more than one node, create a NodeNetworkConfigurationPolicy manifest for each target node. The Kubernetes NMState Operator applies the policy to each node with an NNCP in an unspecified order. Scoping a policy with this approach reduces the length of time for policy application but risks a cluster-wide outage if an error is in the cluster’s configuration. To avoid this type of error, initially apply NNCP to some nodes, and after you confirm they are configured correctly, proceed with applying the policy to the remaining nodes.
  • When you need to apply a policy to many nodes but you only want to create a single NNCP for all target nodes, the Kubernetes NMState Operator applies the policy to each node in sequence. You can set the speed and coverage of policy application for target nodes with the maxUnavailable parameter in the cluster configuration. By setting a lower percentage value for the parameter, you can reduce the risk of a cluster-wide outage if the outage impacts the small percentage of nodes that are receiving the policy application.
  • Consider specifying all related network configurations in a single policy.
  • When a node restarts, the Kubernetes NMState Operator cannot control the order that it applies policies to nodes. The Kubernetes NMState Operator might apply interdependent policies in a sequence that results in a degraded network object.

29.2.5.1. 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/v1
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.

29.2.5.2. Example: VLAN interface node network configuration policy

Create a VLAN interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy manifest to the cluster.

Note

Define all related configurations for the VLAN interface of a node in a single NodeNetworkConfigurationPolicy manifest. For example, define the VLAN interface for a node and the related routes for the VLAN interface in the same NodeNetworkConfigurationPolicy manifest.

When a node restarts, the Kubernetes NMState Operator cannot control the order in which policies are applied. Therefore, if you use separate policies for related network configurations, the Kubernetes NMState Operator might apply these policies in a sequence that results in a degraded network object.

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/v1
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. When deploying on bare metal, only the <interface_name>.<vlan_number> VLAN format is supported.
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.

29.2.5.3. Example: Bond interface node network configuration policy

Create a bond interface on nodes in the cluster by applying a NodeNetworkConfigurationPolicy manifest to the cluster.

Note

OpenShift Container Platform only supports the following bond modes:

  • mode=1 active-backup
  • mode=2 balance-xor
  • mode=4 802.3ad

Other bond modes are not supported.

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/v1
kind: NodeNetworkConfigurationPolicy
metadata:
  name: bond0-eth1-eth2-policy 1
spec:
  nodeSelector: 2
    kubernetes.io/hostname: <node01> 3
  desiredState:
    interfaces:
    - name: bond0 4
      description: Bond with ports 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
        port: 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.

29.2.5.4. 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/v1
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.

29.2.5.5. 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 YAML file creates a bond that is named bond10 across two NICs and VLAN that is named bond10.103 that connects to the bond. 

apiVersion: nmstate.io/v1
kind: NodeNetworkConfigurationPolicy
metadata:
  name: bond-vlan 1
spec:
  nodeSelector: 2
    kubernetes.io/hostname: <node01> 3
  desiredState:
    interfaces:
    - name: bond10 4
      description: Bonding eth2 and eth3 5
      type: bond 6
      state: up 7
      link-aggregation:
        mode: balance-xor 8
        options:
          miimon: '140' 9
        port: 10
        - eth2
        - eth3
    - name: bond10.103 11
      description: vlan using bond10 12
      type: vlan 13
      state: up 14
      vlan:
         base-iface: bond10 15
         id: 103 16
      ipv4:
        dhcp: true 17
        enabled: true 18
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 hostname node selector.
4 11
Name of the interface.
5 12
Optional: Human-readable description of the interface.
6 13
The type of interface.
7 14
The requested state for the interface after creation.
8
The driver mode for the bond.
9
Optional: This example uses miimon to inspect the bond link every 140ms.
10
The subordinate node NICs in the bond.
15
The node NIC to which the VLAN is attached.
16
The VLAN tag.
17
Optional: If you do not use dhcp, you can either set a static IP or leave the interface without an IP address.
18
Enables ipv4 in this example.

29.2.6. Capturing the static IP of a NIC attached to a bridge

Important

Capturing the static IP of a NIC 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.

29.2.6.1. Example: Linux bridge interface node network configuration policy to inherit static IP address from the NIC attached to the bridge

Create a Linux bridge interface on nodes in the cluster and transfer the static IP configuration of the NIC to the bridge by applying a single NodeNetworkConfigurationPolicy manifest to the cluster.

The following YAML file is an example of a manifest for a Linux bridge interface. It includes sample values that you must replace with your own information. 

apiVersion: nmstate.io/v1
kind: NodeNetworkConfigurationPolicy
metadata:
  name: br1-eth1-copy-ipv4-policy 1
spec:
  nodeSelector: 2
    node-role.kubernetes.io/worker: ""
  capture:
    eth1-nic: interfaces.name=="eth1" 3
    eth1-routes: routes.running.next-hop-interface=="eth1"
    br1-routes: capture.eth1-routes | routes.running.next-hop-interface := "br1"
  desiredState:
    interfaces:
      - name: br1
        description: Linux bridge with eth1 as a port
        type: linux-bridge 4
        state: up
        ipv4: "{{ capture.eth1-nic.interfaces.0.ipv4 }}" 5
        bridge:
          options:
            stp:
              enabled: false
          port:
            - name: eth1 6
     routes:
        config: "{{ capture.br1-routes.routes.running }}"
1
The name of the policy.
2
Optional: If you do not include the nodeSelector parameter, the policy applies to all nodes in the cluster. This example uses the node-role.kubernetes.io/worker: "" node selector to select all worker nodes in the cluster.
3
The reference to the node NIC to which the bridge attaches.
4
The type of interface. This example creates a bridge.
5
The IP address of the bridge interface. This value matches the IP address of the NIC which is referenced by the spec.capture.eth1-nic entry.
6
The node NIC to which the bridge attaches.

Additional resources

29.2.7. Examples: IP management

The following example configuration snippets show 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.

29.2.7.1. 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:
        dhcp: false
        address:
        - ip: 192.168.122.250 1
          prefix-length: 24
        enabled: true
# ...
1
Replace this value with the static IP address for the interface.

29.2.7.2. 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
# ...

29.2.7.3. 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
# ...

29.2.7.4. DNS

By default, the nmstate API stores DNS values globally as against storing them in a network interface. For certain situations, you must configure a network interface to store DNS values. To define a DNS configuration for a network interface, you must initially specify the dns-resolver section in the network interface’s YAML configuration file.

Tip

Setting a DNS configuration is comparable to modifying the /etc/resolv.conf file.

Important

You cannot use br-ex bridge, an OVNKubernetes-managed Open vSwitch bridge, as the interface when configuring DNS resolvers.

The following example shows a default situation that stores DNS values globally:

  • Configure a static DNS without a network interface. Note that when updating the /etc/resolv.conf file on a host node, you do not need to specify an interface, IPv4 or IPv6, in the NodeNetworkConfigurationPolicy (NNCP) manifest.

    Example of a DNS configuration for a network interface that globally stores DNS values

    apiVersion: nmstate.io/v1
kind: NodeNetworkConfigurationPolicy
metadata:
 name: worker-0-dns-testing
spec:
  nodeSelector:
    kubernetes.io/hostname: <target_node>
  desiredState:
    dns-resolver:
      config:
        search:
        - example.com
        - example.org
        server:
        - 2001:db8:f::1
        - 192.0.2.251
# ...

The following examples show situations that require configuring a network interface to store DNS values:

  • If you want to rank a static DNS name server over a dynamic DNS name server, define the interface that runs either the Dynamic Host Configuration Protocol (DHCP) or the IPv6 Autoconfiguration (autoconf) mechanism in the network interface YAML configuration file.

    Example configuration that adds 192.0.2.1 to DNS name servers retrieved from the DHCPv4 network protocol

    # ...
dns-resolver:
  config:
    server:
    - 192.0.2.1
interfaces:
  - name: eth1
    type: ethernet
    state: up
    ipv4:
      enabled: true
      dhcp: true
      auto-dns: true
# ...

  • If you need to configure a network interface to store DNS values instead of adopting the default method, which uses the nmstate API to store DNS values globally, you can set static DNS values and static IP addresses in the network interface YAML file.

    Important

    Storing DNS values at the network interface level might cause name resolution issues after you attach the interface to network components, such as an Open vSwitch (OVS) bridge, a Linux bridge, or a bond.

    Example configuration that stores DNS values at the interface level

    # ...
dns-resolver:
  config:
    search:
    - example.com
    - example.org
    server:
    - 2001:db8:1::d1
    - 2001:db8:1::d2
    - 192.0.2.1
interfaces:
  - name: eth1
    type: ethernet
    state: up
    ipv4:
      address:
      - ip: 192.0.2.251
        prefix-length: 24
      dhcp: false
      enabled: true
    ipv6:
      address:
      - ip: 2001:db8:1::1
        prefix-length: 64
      dhcp: false
      enabled: true
      autoconf: false
# ...

  • If you want to set static DNS search domains and dynamic DNS name servers for your network interface, define the dynamic interface that runs either the Dynamic Host Configuration Protocol (DHCP) or the IPv6 Autoconfiguration (autoconf) mechanism in the network interface YAML configuration file.

    Example configuration that sets example.com and example.org static DNS search domains along with dynamic DNS name server settings

    # ...
dns-resolver:
  config:
    search:
    - example.com
    - example.org
    server: []
interfaces:
  - name: eth1
    type: ethernet
    state: up
    ipv4:
      enabled: true
      dhcp: true
      auto-dns: true
    ipv6:
      enabled: true
      dhcp: true
      autoconf: true
      auto-dns: true
# ...

29.2.7.5. Static routing

The following snippet configures a static route and a static IP on interface eth1. 

dns-resolver:
  config:
# ...
interfaces:
  - name: eth1
    description: Static routing on eth1
    type: ethernet
    state: up
    ipv4:
      dhcp: false
      enabled: true
      address:
      - ip: 192.0.2.251 1
        prefix-length: 24
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
# ...
1
The static IP address for the Ethernet interface.
2
Next hop address for the node traffic. This must be in the same subnet as the IP address set for the Ethernet interface.

29.3. 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.

29.3.1. 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 applied an incorrect configuration, you can use the following example to troubleshoot and correct the failed node network policy. The example attempts to apply a Linux bridge policy to a cluster that has three control plane nodes and three compute nodes. The policy is not applied because the policy references the wrong interface.

To find an error, you need to investigate the available NMState resources. You can then update the policy with the correct configuration.

Prerequisites

  • You ensured that an ens01 interface does not exist on your Linux system.

Procedure

  1. Create a policy on your cluster. The following example creates a simple bridge, br1 that has ens01 as its member: 

    apiVersion: nmstate.io/v1
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
# ...

  2. Apply the policy to your network interface: 

    $ oc apply -f ens01-bridge-testfail.yaml

    Example output

    nodenetworkconfigurationpolicy.nmstate.io/ens01-bridge-testfail created

  3. 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

    The policy status alone does not indicate if it failed on all nodes or a subset of nodes.

  4. 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, the output suggests that the problem is with a specific node configuration. If the policy failed on all nodes, the output 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
control-plane-1.ens01-bridge-testfail        FailedToConfigure
control-plane-2.ens01-bridge-testfail        FailedToConfigure
control-plane-3.ens01-bridge-testfail        FailedToConfigure
compute-1.ens01-bridge-testfail              FailedToConfigure
compute-2.ens01-bridge-testfail              FailedToConfigure
compute-3.ens01-bridge-testfail              FailedToConfigure

  5. View one of the failed enactments. The following command uses the output tool jsonpath to filter the output: 

    $ oc get nnce compute-1.ens01-bridge-testfail -o jsonpath='{.status.conditions[?(@.type=="Failing")].message}'

    Example output

    [2024-10-10T08:40:46Z INFO  nmstatectl] Nmstate version: 2.2.37
NmstateError: InvalidArgument: Controller interface br1 is holding unknown port ens01

    The previous example shows the output from an InvalidArgument error that indicates that the ens01 is an unknown port. For this example, you might need to change the port configuration in the policy configuration file.

  6. 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 the control-plane-1 node: 

    $ oc get nns control-plane-1 -o yaml

    The output shows that the interface name on the nodes is ens1 but the failed policy incorrectly uses ens01:

    Example output

       - ipv4:
# ...
      name: ens1
      state: up
      type: ethernet

  7. Correct the error by editing the existing policy: 

    $ oc edit nncp ens01-bridge-testfail
    # ...
          port:
            - name: ens1

    Save the policy to apply the correction.

  8. 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.

29.3.2. Troubleshooting DNS connectivity issues in a disconnected environment

If you experience DNS connectivity issues when configuring nmstate in a disconnected environment, you can configure the DNS server to resolve the list of name servers for the domain root-servers.net.

Important

Ensure that the DNS server includes a name server (NS) entry for the root-servers.net zone. The DNS server does not need to forward a query to an upstream resolver, but the server must return a correct answer for the NS query.

29.3.2.1. Configuring the bind9 DNS named server

For a cluster configured to query a bind9 DNS server, you can add the root-servers.net zone to a configuration file that contains at least one NS record. For example you can use the /var/named/named.localhost as a zone file that already matches this criteria.

Procedure

  1. Add the root-servers.net zone at the end of the /etc/named.conf configuration file by running the following command: 

    $ cat >> /etc/named.conf <<EOF
zone "root-servers.net" IN {
    	type master;
    	file "named.localhost";
};
EOF

  2. Restart the named service by running the following command: 

    $ systemctl restart named

  3. Confirm that the root-servers.net zone is present by running the following command: 

    $ journalctl -u named|grep root-servers.net

    Example output

    Jul 03 15:16:26 rhel-8-10 bash[xxxx]: zone root-servers.net/IN: loaded serial 0
Jul 03 15:16:26 rhel-8-10 named[xxxx]: zone root-servers.net/IN: loaded serial 0

  4. Verify that the DNS server can resolve the NS record for the root-servers.net domain by running the following command: 

    $ host -t NS root-servers.net. 127.0.0.1

    Example output

    Using domain server:
Name: 127.0.0.1
Address: 127.0.0.53
Aliases:
root-servers.net name server root-servers.net.

29.3.2.2. Configuring the dnsmasq DNS server

If you are using dnsmasq as the DNS server, you can delegate resolution of the root-servers.net domain to another DNS server, for example, by creating a new configuration file that resolves root-servers.net using a DNS server that you specify.

  1. Create a configuration file that delegates the domain root-servers.net to another DNS server by running the following command: 

    $ echo 'server=/root-servers.net/<DNS_server_IP>'> /etc/dnsmasq.d/delegate-root-servers.net.conf

  2. Restart the dnsmasq service by running the following command: 

    $ systemctl restart dnsmasq

  3. Confirm that the root-servers.net domain is delegated to another DNS server by running the following command: 

    $ journalctl -u dnsmasq|grep root-servers.net

    Example output

    Jul 03 15:31:25 rhel-8-10 dnsmasq[1342]: using nameserver 192.168.1.1#53 for domain root-servers.net

  4. Verify that the DNS server can resolve the NS record for the root-servers.net domain by running the following command: 

    $ host -t NS root-servers.net. 127.0.0.1

    Example output

    Using domain server:
Name: 127.0.0.1
Address: 127.0.0.1#53
Aliases:
root-servers.net name server root-servers.net.

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