Create a Cluster

This section provides details about creating a new Cluster managed by Cluster API.

If you are not using the ClusterClass, at this point you should already have:

• an InfrastructureCluster resource and one or more InfrastructureMachineTemplate resources
• a control plane resource (for example, a KubeadmControlPlane)
• one or more BootstrapConfigTemplate resources
• one or more MachineDeployment or MachinePool resources

All you need now is a Cluster resource that ties everything together:

---
apiVersion: cluster.x-k8s.io/v1beta2
kind: Cluster
metadata:
  name: my-cluster
spec:
  clusterNetwork:
    pods:
      cidrBlocks:
      - 192.168.0.0/16
  controlPlaneRef:
    apiGroup: controlplane.cluster.x-k8s.io
    kind: KubeadmControlPlane
    name: my-cluster-controlplane
  infrastructureRef:
    apiGroup: infrastructure.cluster.x-k8s.io
    kind: VSphereCluster
    name: my-cluster-infrastructure

Once this is ready, you can apply your manifest, including the Cluster and all the other resources, and Cluster API will orchestrate infrastructure provisioning, Machine bootstrap as well as bootstrapping the Kubernetes cluster hosted on this infrastructure/machines.

Tip

The clusterctl generate cluster command can help you in generating the Cluster and all the other resources starting from templates available for each infrastructure provider.

Using ClusterClass

If you are using the ClusterClass feature, the ClusterClass author takes ownership of the responsibility of defining InfrastructureCluster, ControlPlane and all the other resources described in the previous paragraphs.

As a consequence, all you need to create a cluster managed by Cluster API is to create a Cluster resource with additional information defining the desired cluster topology.

e.g.

apiVersion: cluster.x-k8s.io/v1beta2
kind: Cluster
metadata:
  name: my-cluster
spec:
  clusterNetwork:
    pods:
      cidrBlocks:
        - 192.168.0.0/16
  topology:
    classRef:
      name: vsphere-clusterclass-v0.1.0
    version: v1.34.0
    controlPlane:
      replicas: 3
    workers:
      machineDeployments:
      - class: default-worker
        name: md-0
        replicas: 5

Note

When using ClusterClass, infrastructure settings or machine bootstrap settings are exposed through variables defined by the ClusterClass author.

Cluster API will take care of creating the underlying ControlPlane, MachineDeployment or MachinePool resources corresponding BootstrapConfigTemplate and InfrastructureMachineTemplate automatically.

Tip

The clusterctl generate cluster command can also generate Cluster using ClusterClass (it depends on how templates available for each infrastructure provider are implemented).

Tip

The Cluster.spec.topology field not only provides a very efficient way for defining a cluster configuration, but it also acts as a single point of control for the entire lifecycle of the cluster.