Cluster Network Operator in OKD

The Cluster Network Operator (CNO) deploys and manages the cluster network components on an OKD cluster, including the Container Network Interface (CNI) default network provider plug-in selected for the cluster during installation.

Cluster Network Operator

The Cluster Network Operator implements the network API from the operator.openshift.io API group. The Operator deploys the OpenShift SDN default Container Network Interface (CNI) network provider plug-in, or the default network provider plug-in that you selected during cluster installation, by using a daemon set.

Procedure

The Cluster Network Operator is deployed during installation as a Kubernetes Deployment.

  1. Run the following command to view the Deployment status:

    1. $ oc get -n openshift-network-operator deployment/network-operator

    Example output

    1. NAME               READY   UP-TO-DATE   AVAILABLE   AGE
    2. network-operator   1/1     1            1           56m

  2. Run the following command to view the state of the Cluster Network Operator:

    1. $ oc get clusteroperator/network

    Example output

    1. NAME      VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
    2. network   4.5.4     True        False         False      50m

    The following fields provide information about the status of the operator: AVAILABLE, PROGRESSING, and DEGRADED. The AVAILABLE field is True when the Cluster Network Operator reports an available status condition.

Viewing the cluster network configuration

Every new OKD installation has a network.config object named cluster.

Procedure

  • Use the oc describe command to view the cluster network configuration:

    1. $ oc describe network.config/cluster

    Example output

    1. Name:         cluster
    2. Namespace:
    3. Labels:       <none>
    4. Annotations:  <none>
    5. API Version:  config.openshift.io/v1
    6. Kind:         Network
    7. Metadata:
    8.   Self Link:           /apis/config.openshift.io/v1/networks/cluster
    9. Spec: (1)
    10.   Cluster Network:
    11.     Cidr:         10.128.0.0/14
    12.     Host Prefix:  23
    13.   Network Type:   OpenShiftSDN
    14.   Service Network:
    15.     172.30.0.0/16
    16. Status: (2)
    17.   Cluster Network:
    18.     Cidr:               10.128.0.0/14
    19.     Host Prefix:        23
    20.   Cluster Network MTU:  8951
    21.   Network Type:         OpenShiftSDN
    22.   Service Network:
    23.     172.30.0.0/16
    24. Events:  <none>
    1The Spec field displays the configured state of the cluster network.
    2The Status field displays the current state of the cluster network configuration.

Viewing Cluster Network Operator status

You can inspect the status and view the details of the Cluster Network Operator using the oc describe command.

Procedure

  • Run the following command to view the status of the Cluster Network Operator:

    1. $ oc describe clusteroperators/network

Viewing Cluster Network Operator logs

You can view Cluster Network Operator logs by using the oc logs command.

Procedure

  • Run the following command to view the logs of the Cluster Network Operator:

    1. $ oc logs --namespace=openshift-network-operator deployment/network-operator

Cluster Network Operator configuration

The configuration for the cluster network is specified as part of the Cluster Network Operator (CNO) configuration and stored in a custom resource (CR) object that is named cluster. The CR specifies the fields for the Network API in the operator.openshift.io API group.

The CNO configuration inherits the following fields during cluster installation from the Network API in the Network.config.openshift.io API group and these fields cannot be changed:

clusterNetwork

IP address pools from which pod IP addresses are allocated.

serviceNetwork

IP address pool for services.

defaultNetwork.type

Cluster network provider, such as OpenShift SDN or OVN-Kubernetes.

After cluster installation, you cannot modify the fields listed in the previous section.

You can specify the cluster network provider configuration for your cluster by setting the fields for the defaultNetwork object in the CNO object named cluster.

Cluster Network Operator configuration object

The fields for the Cluster Network Operator (CNO) are described in the following table:

Table 1. Cluster Network Operator configuration object
FieldTypeDescription

metadata.name

string

The name of the CNO object. This name is always cluster.

spec.clusterNetwork

array

A list specifying the blocks of IP addresses from which pod IP addresses are allocated and the subnet prefix length assigned to each individual node in the cluster. For example:

  1. spec:
  2.   clusterNetwork:
  3.   - cidr: 10.128.0.0/19
  4.     hostPrefix: 23
  5.   - cidr: 10.128.32.0/19
  6.     hostPrefix: 23

This value is ready-only and inherited from the Network.config.openshift.io object named cluster during cluster installation.

spec.serviceNetwork

array

A block of IP addresses for services. The OpenShift SDN and OVN-Kubernetes Container Network Interface (CNI) network providers support only a single IP address block for the service network. For example:

  1. spec:
  2.   serviceNetwork:
  3.   - 172.30.0.0/14

This value is ready-only and inherited from the Network.config.openshift.io object named cluster during cluster installation.

spec.defaultNetwork

object

Configures the Container Network Interface (CNI) cluster network provider for the cluster network.

spec.kubeProxyConfig

object

The fields for this object specify the kube-proxy configuration. If you are using the OVN-Kubernetes cluster network provider, the kube-proxy configuration has no effect.

defaultNetwork object configuration

The values for the defaultNetwork object are defined in the following table:

Table 2. defaultNetwork object
FieldTypeDescription

type

string

Either OpenShiftSDN or OVNKubernetes. The cluster network provider is selected during installation. This value cannot be changed after cluster installation.

OKD uses the OVN-Kubernetes Container Network Interface (CNI) cluster network provider by default.

openshiftSDNConfig

object

This object is only valid for the OpenShift SDN cluster network provider.

ovnKubernetesConfig

object

This object is only valid for the OVN-Kubernetes cluster network provider.

Configuration for the OpenShift SDN CNI cluster network provider

The following table describes the configuration fields for the OpenShift SDN Container Network Interface (CNI) cluster network provider.

Table 3. openshiftSDNConfig object
FieldTypeDescription

mode

string

The network isolation mode for OpenShift SDN.

mtu

integer

The maximum transmission unit (MTU) for the VXLAN overlay network. This value is normally configured automatically.

vxlanPort

integer

The port to use for all VXLAN packets. The default value is 4789.

You can only change the configuration for your cluster network provider during cluster installation.

Example OpenShift SDN configuration

  1. defaultNetwork:
  2.   type: OpenShiftSDN
  3.   openshiftSDNConfig:
  4.     mode: NetworkPolicy
  5.     mtu: 1450
  6.     vxlanPort: 4789
Configuration for the OVN-Kubernetes CNI cluster network provider

The following table describes the configuration fields for the OVN-Kubernetes CNI cluster network provider.

Table 4. ovnKubernetesConfig object
FieldTypeDescription

mtu

integer

The maximum transmission unit (MTU) for the Geneve (Generic Network Virtualization Encapsulation) overlay network. This value is normally configured automatically.

genevePort

integer

The UDP port for the Geneve overlay network.

ipsecConfig

object

If the field is present, IPsec is enabled for the cluster.

policyAuditConfig

object

Specify a configuration object for customizing network policy audit logging. If unset, the defaults audit log settings are used.

Table 5. policyAuditConfig object
FieldTypeDescription

rateLimit

integer

The maximum number of messages to generate every second per node. The default value is 20 messages per second.

maxFileSize

integer

The maximum size for the audit log in bytes. The default value is 50000000 or 50 MB.

destination

string

One of the following additional audit log targets:

    libc

    The libc syslog() function of the journald process on the host.

    udp:<host>:<port>

    A syslog server. Replace <host>:<port> with the host and port of the syslog server.

    unix:<file>

    A Unix Domain Socket file specified by <file>.

    null

    Do not send the audit logs to any additional target.

syslogFacility

string

The syslog facility, such as kern, as defined by RFC5424. The default value is local0.

You can only change the configuration for your cluster network provider during cluster installation.

Example OVN-Kubernetes configuration

  1. defaultNetwork:
  2.   type: OVNKubernetes
  3.   ovnKubernetesConfig:
  4.     mtu: 1400
  5.     genevePort: 6081
  6.     ipsecConfig: {}

kubeProxyConfig object configuration

The values for the kubeProxyConfig object are defined in the following table:

Table 6. kubeProxyConfig object
FieldTypeDescription

iptablesSyncPeriod

string

The refresh period for iptables rules. The default value is 30s. Valid suffixes include s, m, and h and are described in the Go time package documentation.

Because of performance improvements introduced in OKD 4.3 and greater, adjusting the iptablesSyncPeriod parameter is no longer necessary.

proxyArguments.iptables-min-sync-period

array

The minimum duration before refreshing iptables rules. This field ensures that the refresh does not happen too frequently. Valid suffixes include s, m, and h and are described in the Go time package. The default value is:

  1. kubeProxyConfig:
  2.   proxyArguments:
  3.     iptables-min-sync-period:
  4.     - 0s

Cluster Network Operator example configuration

A complete CNO configuration is specified in the following example:

Example Cluster Network Operator object

  1. apiVersion: operator.openshift.io/v1
  2. kind: Network
  3. metadata:
  4.   name: cluster
  5. spec:
  6.   clusterNetwork: (1)
  7.   - cidr: 10.128.0.0/14
  8.     hostPrefix: 23
  9.   serviceNetwork: (1)
  10.   - 172.30.0.0/16
  11.   defaultNetwork: (1)
  12.     type: OpenShiftSDN
  13.     openshiftSDNConfig:
  14.       mode: NetworkPolicy
  15.       mtu: 1450
  16.       vxlanPort: 4789
  17.   kubeProxyConfig:
  18.     iptablesSyncPeriod: 30s
  19.     proxyArguments:
  20.       iptables-min-sync-period:
  21.       - 0s
1Configured only during cluster installation.

Additional resources