Upgrading Cluster API components

When to upgrade

In general, it’s recommended to upgrade to the latest version of Cluster API to take advantage of bug fixes, new features and improvements.


If moving between different API versions, there may be additional tasks that you need to complete. See below for instructions moving between v1alpha2 and v1alpha3.

Ensure that the version of Cluster API is compatible with the Kubernetes version of the management cluster.

Upgrading to newer versions of 0.3.x

It is recommended to use clusterctl to upgrade between versions of Cluster API 0.3.x.

Upgrading from Cluster API v1alpha2 (0.2.x) to Cluster API v1alpha3 (0.3.x)

We will be using the clusterctl init command to upgrade an existing management cluster from v1alpha2 to v1alpha3.

For detailed information about the changes from v1alpha2 to v1alpha3, please refer to the Cluster API v1alpha2 compared to v1alpha3 section.


There are a few preliminary steps needed to be able to run clusterctl init on a management cluster with v1alpha2 components installed.

Delete the cabpk-system namespace

Delete the cabpk-system namespace by running:

kubectl delete namespace cabpk-system

Delete the core and infrastructure provider controller-manager deployments

Delete the capi-controller-manager deployment from the capi-system namespace:

kubectl delete deployment capi-controller-manager -n capi-system

Depending on your infrastructure provider, delete the controller-manager deployment.

For example, if you are using the AWS provider, delete the capa-controller-manager deployment from the capa-system namespace:

kubectl delete deployment capa-controller-manager -n capa-system

Optional: Ensure preserveUnknownFields is set to ‘false’ for the infrastructure provider CRDs Spec

This should be the case for all infrastructure providers using conversion webhooks to allow upgrading from v1alpha2 to v1alpha3.

This can verified by running kubectl get crd <crd name>.infrastructure.cluster.x-k8s.io -o yaml for all the infrastructure provider CRDs.

Upgrade Cluster API components using clusterctl

Run clusterctl init with the relevant infrastructure flag. For the AWS provider you would run:

clusterctl init --infrastructure aws

You should now be able to manage your resources using the v1alpha3 version of the Cluster API components.

Adopting existing machines into KubeadmControlPlane management

If your cluster has existing machines labeled with cluster.x-k8s.io/control-plane, you may opt in to management of those machines by creating a new KubeadmControlPlane object and updating the associated Cluster object’s controlPlaneRef like so:

apiVersion: "cluster.x-k8s.io/v1alpha3"
kind: Cluster
    apiVersion: controlplane.cluster.x-k8s.io/v1alpha3
    kind: KubeadmControlPlane
    name: controlplane
    namespace: default


  • The KCP controller will refuse to adopt any control plane Machines not bootstrapped with the kubeadm bootstrapper.
  • The KCP controller may immediately begin upgrading Machines post-adoption if they’re out of date.
  • The KCP controller attempts to behave intelligently when adopting existing Machines, but because the bootstrapping process sets various fields in the KubeadmConfig of a machine it’s not always obvious the original user-supplied KubeadmConfig would have been for that machine. The controller attempts to guess this intent to not replace Machines unnecessarily, so if it guesses wrongly, the consequence is that the KCP controller will effect an “upgrade” to its current config.
  • If the cluster’s PKI materials were generated by an initial KubeadmConfig reconcile, they’ll be owned by the KubeadmConfig bound to that machine. The adoption process re-parents these resources to the KCP so they’re not lost during an upgrade, but deleting the KCP post-adoption will destroy those materials.
  • The ClusterConfiguration is only partially reconciled with their ConfigMaps the workload cluster, and kubeadm considers the ConfigMap authoritative. Fields which are reconciled include:
    • kubeadmConfigSpec.clusterConfiguration.etcd.local.imageRepository
    • kubeadmConfigSpec.clusterConfiguration.etcd.local.imageTag
    • kubeadmConfigSpec.clusterConfiguration.dns.imageRepository
    • kubeadmConfigSpec.clusterConfiguration.dns.imageTag
    • Further information can be found in issue 2083