Cluster API now ships with a new experimental package that lives under the
exp/ directory. This is a
temporary location for features which will be moved to their permanent locations after graduation. Users can experiment with these features by enabling them using feature gates.
Enabling Experimental Features for Management Clusters Started with clusterctl
Users can enable/disable features by setting OS environment variables before running
clusterctl init, e.g.:
export EXP_CLUSTER_RESOURCE_SET=true clusterctl init --infrastructure vsphere
As an alternative to environment variables, it is also possible to set variables in the clusterctl config file located at
# Values for environment variable substitution EXP_CLUSTER_RESOURCE_SET: "true"
In case a variable is defined in both the config file and as an OS environment variable, the environment variable takes precedence. For more information on how to set variables for clusterctl, see clusterctl Configuration File
Some features like
MachinePools may require infrastructure providers to implement a separate CRD that handles the infrastructure side of the feature too.
For such a feature to work, infrastructure providers should also enable their controllers if it is implemented as a feature. If it is not implemented as a feature, no additional step is necessary.
As an example, Cluster API Provider Azure (CAPZ) has support for MachinePool through the infrastructure type
Enabling Experimental Features for e2e Tests
One way is to set experimental variables on the clusterctl config file. For CAPI, these configs are under ./test/e2e/config/... such as
variables: EXP_CLUSTER_RESOURCE_SET: "true" EXP_MACHINE_POOL: "true" CLUSTER_TOPOLOGY: "true" EXP_RUNTIME_SDK: "true" EXP_MACHINE_SET_PREFLIGHT_CHECKS: "true"
Another way is to set them as environmental variables before running e2e tests.
Enabling Experimental Features on Tilt
On development environments started with
Tilt, features can be enabled by setting the feature variables in
kustomize_substitutions: EXP_CLUSTER_RESOURCE_SET: 'true' EXP_MACHINE_POOL: 'true' CLUSTER_TOPOLOGY: 'true' EXP_RUNTIME_SDK: 'true' EXP_MACHINE_SET_PREFLIGHT_CHECKS: 'true'
For more details on setting up a development environment with
tilt, see Developing Cluster API with Tilt
Enabling Experimental Features on Existing Management Clusters
To enable/disable features on existing management clusters, users can modify CAPI controller manager deployment which will restart all controllers with requested features.
kubectl edit -n capi-system deployment.apps/capi-controller-manager
// Enable/disable available features by modifying Args below. Args: --leader-elect --feature-gates=MachinePool=true,ClusterResourceSet=true
Similarly, to validate if a particular feature is enabled, see cluster-api-provider deployment arguments by:
kubectl describe -n capi-system deployment.apps/capi-controller-manager
Active Experimental Features
Warning: Experimental features are unreliable, i.e., some may one day be promoted to the main repository, or they may be modified arbitrarily or even disappear altogether. In short, they are not subject to any compatibility or deprecation promise.