Installing the MetalLB Operator - Load balancing with MetalLB | Networking

Installing the MetalLB Operator from the OperatorHub using the web console
Installing from OperatorHub using the CLI
Starting MetalLB on your cluster
Deployment specifications for MetalLB
Additional resources
Next steps

As a cluster administrator, you can add the MetallB Operator so that the Operator can manage the lifecycle for an instance of MetalLB on your cluster.

MetalLB and IP failover are incompatible. If you configured IP failover for your cluster, perform the steps to remove IP failover before you install the Operator.

Installing the MetalLB Operator from the OperatorHub using the web console

As a cluster administrator, you can install the MetalLB Operator by using the OpenShift Container Platform web console.

Prerequisites

Procedure

In the OpenShift Container Platform web console, navigate to Operators → OperatorHub.
Type a keyword into the Filter by keyword box or scroll to find the Operator you want. For example, type metallb to find the MetalLB Operator.

You can also filter options by Infrastructure Features. For example, select Disconnected if you want to see Operators that work in disconnected environments, also known as restricted network environments.
On the Install Operator page, accept the defaults and click Install.

Verification

To confirm that the installation is successful:
1. Navigate to the Operators → Installed Operators page.
2. Check that the Operator is installed in the openshift-operators namespace and that its status is Succeeded.
If the Operator is not installed successfully, check the status of the Operator and review the logs:
1. Navigate to the Operators → Installed Operators page and inspect the Status column for any errors or failures.
2. Navigate to the Workloads → Pods page and check the logs in any pods in the openshift-operators project that are reporting issues.

Installing from OperatorHub using the CLI

Instead of using the OpenShift Container Platform web console, you can install an Operator from OperatorHub using the CLI. You can use the OpenShift CLI (oc) to install the MetalLB Operator.

It is recommended that when using the CLI you install the Operator in the metallb-system namespace.

Prerequisites

A cluster installed on bare-metal hardware.
Install the OpenShift CLI (oc).
Log in as a user with cluster-admin privileges.

Procedure

Create a namespace for the MetalLB Operator by entering the following command:

$ cat << EOF | oc apply -f -
apiVersion: v1
kind: Namespace
metadata:
  name: metallb-system
EOF

Create an Operator group custom resource (CR) in the namespace:

$ cat << EOF | oc apply -f -
apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: metallb-operator
  namespace: metallb-system
EOF

Confirm the Operator group is installed in the namespace:

$ oc get operatorgroup -n metallb-system

Example output

NAME               AGE
metallb-operator   14m

Create a Subscription CR:

Define the Subscription CR and save the YAML file, for example, metallb-sub.yaml:

apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: metallb-operator-sub
  namespace: metallb-system
spec:
  channel: stable
  name: metallb-operator
  source: redhat-operators (1)
  sourceNamespace: openshift-marketplace

1	You must specify the `redhat-operators` value.

To create the Subscription CR, run the following command:
```
$ oc create -f metallb-sub.yaml
```

Optional: To ensure BGP and BFD metrics appear in Prometheus, you can label the namespace as in the following command:
```
$ oc label ns metallb-system "openshift.io/cluster-monitoring=true"
```

Verification

The verification steps assume the MetalLB Operator is installed in the metallb-system namespace.

Confirm the install plan is in the namespace:

$ oc get installplan -n metallb-system

Example output

NAME            CSV                                   APPROVAL    APPROVED
install-wzg94   metallb-operator.4.12.0-nnnnnnnnnnnn   Automatic   true

Installation of the Operator might take a few seconds.

To verify that the Operator is installed, enter the following command:

$ oc get clusterserviceversion -n metallb-system \
  -o custom-columns=Name:.metadata.name,Phase:.status.phase

Example output

Name                                  Phase
metallb-operator.4.12.0-nnnnnnnnnnnn   Succeeded

Starting MetalLB on your cluster

After you install the Operator, you need to configure a single instance of a MetalLB custom resource. After you configure the custom resource, the Operator starts MetalLB on your cluster.

Prerequisites

Install the OpenShift CLI (oc).
Log in as a user with cluster-admin privileges.
Install the MetalLB Operator.

Procedure

This procedure assumes the MetalLB Operator is installed in the metallb-system namespace. If you installed using the web console substitute openshift-operators for the namespace.

Create a single instance of a MetalLB custom resource:

$ cat << EOF | oc apply -f -
apiVersion: metallb.io/v1beta1
kind: MetalLB
metadata:
  name: metallb
  namespace: metallb-system
EOF

Verification

Confirm that the deployment for the MetalLB controller and the daemon set for the MetalLB speaker are running.

Verify that the deployment for the controller is running:

$ oc get deployment -n metallb-system controller

Example output

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
controller   1/1     1            1           11m

Verify that the daemon set for the speaker is running:
```
$ oc get daemonset -n metallb-system speaker
```
Example output
```
NAME      DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR            AGE
speaker   6         6         6       6            6           kubernetes.io/os=linux   18m
```
The example output indicates 6 speaker pods. The number of speaker pods in your cluster might differ from the example output. Make sure the output indicates one pod for each node in your cluster.

Deployment specifications for MetalLB

When you start an instance of MetalLB using the MetalLB custom resource, you can configure deployment specifications in the MetalLB custom resource to manage how the controller or speaker pods deploy and run in your cluster. Use these deployment specifications to manage the following tasks:

Select nodes for MetalLB pod deployment.
Manage scheduling by using pod priority and pod affinity.
Assign CPU limits for MetalLB pods.
Assign a container RuntimeClass for MetalLB pods.
Assign metadata for MetalLB pods.

Limit speaker pods to specific nodes

By default, when you start MetalLB with the MetalLB Operator, the Operator starts an instance of a speaker pod on each node in the cluster. Only the nodes with a speaker pod can advertise a load balancer IP address. You can configure the MetalLB custom resource with a node selector to specify which nodes run the speaker pods.

The most common reason to limit the speaker pods to specific nodes is to ensure that only nodes with network interfaces on specific networks advertise load balancer IP addresses. Only the nodes with a running speaker pod are advertised as destinations of the load balancer IP address.

If you limit the speaker pods to specific nodes and specify local for the external traffic policy of a service, then you must ensure that the application pods for the service are deployed to the same nodes.

Example configuration to limit speaker pods to worker nodes

apiVersion: metallb.io/v1beta1
kind: MetalLB
metadata:
  name: metallb
  namespace: metallb-system
spec:
  nodeSelector:  (1)
    node-role.kubernetes.io/worker: ""
  speakerTolerations:   (2)
  - key: "Example"
    operator: "Exists"
    effect: "NoExecute"

1	The example configuration specifies to assign the speaker pods to worker nodes, but you can specify labels that you assigned to nodes or any valid node selector.
2	In this example configuration, the pod that this toleration is attached to tolerates any taint that matches the `key` value and `effect` value using the `operator`.

After you apply a manifest with the spec.nodeSelector field, you can check the number of pods that the Operator deployed with the oc get daemonset -n metallb-system speaker command. Similarly, you can display the nodes that match your labels with a command like oc get nodes -l node-role.kubernetes.io/worker=.

You can optionally allow the node to control which speaker pods should, or should not, be scheduled on them by using affinity rules. You can also limit these pods by applying a list of tolerations. For more information about affinity rules, taints, and tolerations, see the additional resources.

Configuring pod priority and pod affinity in a MetalLB deployment

You can optionally assign pod priority and pod affinity rules to controller and speaker pods by configuring the MetalLB custom resource. The pod priority indicates the relative importance of a pod on a node and schedules the pod based on this priority. Set a high priority on your controller or speaker pod to ensure scheduling priority over other pods on the node.

Pod affinity manages relationships among pods. Assign pod affinity to the controller or speaker pods to control on what node the scheduler places the pod in the context of pod relationships. For example, you can use pod affinity rules to ensure that certain pods are located on the same node or nodes, which can help improve network communication and reduce latency between those components.

Prerequisites

You are logged in as a user with cluster-admin privileges.
You have installed the MetalLB Operator.
You have started the MetalLB Operator on your cluster.

Procedure

Create a PriorityClass custom resource, such as myPriorityClass.yaml, to configure the priority level. This example defines a PriorityClass named high-priority with a value of 1000000. Pods that are assigned this priority class are considered higher priority during scheduling compared to pods with lower priority classes:
```
apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: high-priority
value: 1000000
```
Apply the PriorityClass custom resource configuration:
```
$ oc apply -f myPriorityClass.yaml
```

Create a MetalLB custom resource, such as MetalLBPodConfig.yaml, to specify the priorityClassName and podAffinity values:

apiVersion: metallb.io/v1beta1
kind: MetalLB
metadata:
  name: metallb
  namespace: metallb-system
spec:
  logLevel: debug
  controllerConfig:
    priorityClassName: high-priority (1)
    affinity:
      podAffinity: (2)
        requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchLabels:
             app: metallb
          topologyKey: kubernetes.io/hostname
  speakerConfig:
    priorityClassName: high-priority
    affinity:
      podAffinity:
        requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchLabels:
             app: metallb
          topologyKey: kubernetes.io/hostname

1 Specifies the priority class for the MetalLB controller pods. In this case, it is set to high-priority.

2 Specifies that you are configuring pod affinity rules. These rules dictate how pods are scheduled in relation to other pods or nodes. This configuration instructs the scheduler to schedule pods that have the label app: metallb onto nodes that share the same hostname. This helps to co-locate MetalLB-related pods on the same nodes, potentially optimizing network communication, latency, and resource usage between these pods.

Apply the MetalLB custom resource configuration:
```
$ oc apply -f MetalLBPodConfig.yaml
```

Verification

To view the priority class that you assigned to pods in the metallb-system namespace, run the following command:

$ oc get pods -n metallb-system -o custom-columns=NAME:.metadata.name,PRIORITY:.spec.priorityClassName

Example output

NAME                                                 PRIORITY
controller-584f5c8cd8-5zbvg                          high-priority
metallb-operator-controller-manager-9c8d9985-szkqg   <none>
metallb-operator-webhook-server-c895594d4-shjgx      <none>
speaker-dddf7                                        high-priority

To verify that the scheduler placed pods according to pod affinity rules, view the metadata for the pod’s node or nodes by running the following command:
```
$ oc get pod -o=custom-columns=NODE:.spec.nodeName,NAME:.metadata.name -n metallb-system
```

Configuring pod CPU limits in a MetalLB deployment

You can optionally assign pod CPU limits to controller and speaker pods by configuring the MetalLB custom resource. Defining CPU limits for the controller or speaker pods helps you to manage compute resources on the node. This ensures all pods on the node have the necessary compute resources to manage workloads and cluster housekeeping.

Prerequisites

You are logged in as a user with cluster-admin privileges.
You have installed the MetalLB Operator.

Procedure

Create a MetalLB custom resource file, such as CPULimits.yaml, to specify the cpu value for the controller and speaker pods:

apiVersion: metallb.io/v1beta1
kind: MetalLB
metadata:
  name: metallb
  namespace: metallb-system
spec:
  logLevel: debug
  controllerConfig:
    resources:
      limits:
        cpu: "200m"
  speakerConfig:
    resources:
      limits:
        cpu: "300m"

Apply the MetalLB custom resource configuration:
```
$ oc apply -f CPULimits.yaml
```

Verification

To view compute resources for a pod, run the following command, replacing <pod_name> with your target pod:
```
$ oc describe pod <pod_name>
```

Additional resources

Next steps

Configuring MetalLB address pools