Cluster API Version Support and Kubernetes Version Skew Policy

Supported Versions

The Cluster API team maintains release branches for (v1alpha4) v0.4 and (v1alpha3) v0.3, the two most recent releases.

Releases include these components:

  • Core Provider
  • Kubeadm Bootstrap Provider
  • Kubeadm Control Plane Provider
  • clusterctl client

All Infrastructure Providers are maintained by independent teams. Other Bootstrap and Control Plane Providers are also maintained by independent teams. For more information about their version support, see below.

Supported Kubernetes Versions

The project aims to keep the current minor release compatible with the actively supported Kubernetes minor releases, i.e., the current release (N), N-1, and N-2. To find out the exact range of Kubernetes versions supported by each component, please see the tables below.

See the following section to understand how cluster topology affects version support.

Kubernetes Version Support As A Function Of Cluster Topology

The Core Provider, Kubeadm Bootstrap Provider, and Kubeadm Control Plane Provider run on the Management Cluster, and clusterctl talks to that cluster’s API server.

In some cases, the Management Cluster is separate from the Workload Clusters. The Kubernetes version of the Management and Workload Clusters are allowed to be different.

Management Clusters and Workload Clusters can be upgraded independently and in any order, however, if you are additionally moving from v1alpha3 (v0.3.x) to v1alpha4 (v0.4.x) as part of the upgrade roll out, the management cluster will need to be upgraded to at least v1.19.x, prior to upgrading any workload cluster using Cluster API v1alpha4 (v0.4.x)

These diagrams show the relationships between components in a Cluster API release (yellow), and other components (white).

Management And Workload Cluster Are the Same (Self-hosted)

Management/Workload Same Cluster

Management And Workload Clusters Are Separate

Management/Workload Separate Clusters

Release Components

Core Provider (cluster-api-controller)

CAPI v1alpha3 (v0.3) ManagementCAPI v1alpha3 (v0.3) WorkloadCAPI v1alpha4 (v0.4) ManagementCAPI v1alpha4 (v0.4) Workload
Kubernetes v1.16
Kubernetes v1.17
Kubernetes v1.18
Kubernetes v1.19
Kubernetes v1.20
Kubernetes v1.21
Kubernetes v1.22

The Core Provider also talks to API server of every Workload Cluster. Therefore, the Workload Cluster’s Kubernetes version must also be compatible.

Kubeadm Bootstrap Provider (kubeadm-bootstrap-controller)

CAPI v1alpha3 (v0.3) ManagementCAPI v1alpha3 (v0.3) WorkloadCAPI v1alpha4 (v0.4) ManagementCAPI v1alpha4 (v0.4) Workload
Kubernetes v1.16 + kubeadm/v1beta2
Kubernetes v1.17 + kubeadm/v1beta2
Kubernetes v1.18 + kubeadm/v1beta2
Kubernetes v1.19 + kubeadm/v1beta2
Kubernetes v1.20 + kubeadm/v1beta2
Kubernetes v1.21 + kubeadm/v1beta2
Kubernetes v1.22 + kubeadm/v1beta2 (v0.3) kubeadm/v1beta3 (v0.4)

The Kubeadm Bootstrap Provider generates kubeadm configuration using the API version recommended for the target Kubernetes version.

Kubeadm Control Plane Provider (kubeadm-control-plane-controller)

CAPI v1alpha3 (v0.3) ManagementCAPI v1alpha3 (v0.3) WorkloadCAPI v1alpha4 (v0.4) ManagementCAPI v1alpha4 (v0.4) Workload
Kubernetes v1.16 + etcd/v3
Kubernetes v1.17 + etcd/v3
Kubernetes v1.18 + etcd/v3
Kubernetes v1.19 + etcd/v3
Kubernetes v1.20 + etcd/v3
Kubernetes v1.21 + etcd/v3
Kubernetes v1.22 + etcd/v3

The Kubeadm Control Plane Provider talks to the API server and etcd members of every Workload Cluster whose control plane it owns. It uses the etcd v3 API.

The Kubeadm Control Plane requires the Kubeadm Bootstrap Provider.


It is strongly recommended to always use the latest version of clusterctl, in order to get all the fixes/latest changes.

In case of upgrades, clusterctl should be upgraded first and then used to upgrade all the other components.

Providers Maintained By Independent Teams

In general, if a Provider version M says it is compatible with Cluster API version N, then version M must be compatible with a subset of the Kubernetes versions supported by Cluster API version N.

To understand the version compatibility of a specific provider, please see its documentation. This book includes a list of independent providers