Data plane registration

Background

Details of the multi-cluster connectivity architecture can be found here. Details regarding ClientConfigs, ServiceAccounts, and Kubeconfig secrets are dealt with there.

Proceed with caution before deleting a ClientConfig or the secrets backing it. If there are any K8ssandraClusters that use the kube config provided by the ClientConfig, then the operator won’t be able to properly manage them.

Creating a ClientConfig and Kubeconfig secret

Registering a data plane to a control plane can be error prone if done by hand. Instead use the k8ssandra-client CLI tool which can be found here. It can be installed as a kubectl plugin by placing it on your $PATH (invoked with kubectl k8ssandra ...) or run completely separately (invoked with ./kubectl-k8ssandra ...).

An example command to register a data plane to a control plane would be kubectl k8ssandra register --source-context gke_k8ssandra_us-central1-c_registration-2 --dest-context gke_k8ssandra_us-central1-c_registration-1 where the source context (gke_k8ssandra_us-central1-c_registration-2) is the data plane (because that’s the source of the credentials) and the destination context (gke_k8ssandra_us-central1-c_registration-1) is the control plane.

If the operator was installed in a different namespace than k8ssandra-operator in either the source or the destination cluster, use the following flags to indicate the actual namespaces:

• --dest-namespace <namespace>
• --source-namespace <namespace>

A full list of options for this command can be found by using the --help flag.

Referencing a remote data plane within a K8ssandraCluster

Within the K8ssandraCluster DC list, the k8sContext can be used to reference a remote data plane. When creating ClientConfigs using k8ssandra-client, you will find that you can simply refer to the data plane using the name of the ClientConfig resource. However, if the ClientConfig has been created by hand, the ClientConfig spec.contextName and meta.name may be different, in which case the spec.contextName should be used. We recommend using k8ssandra-client to register data planes due to complexities like these.