Migration from clusters with names that don't match k8s name syntax is failing

[vstariradev]

I'm trying to perform migration from an existing k8s cassandra cluster running in a statefulset. The cluster name is RGS.

Following the guide here I have to create a new K8ssandraCluster with name RGS. However, k8s won't allow that:

The K8ssandraCluster "RGS" is invalid: metadata.name: Invalid value: "RGS": a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')

https://github.com/k8ssandra/k8ssandra-operator/blob/5045d5abf0904c6988bbb005fd62806950369c8f/docs/content/en/tasks/migrate/_index.md?plain=1#L148C87-L148C87

Renaming a cassandra cluster is not a supported operation as per: https://dba.stackexchange.com/a/316208. It would be nice to warn about this limitation or just add it to the pre-requisites section (https://docs.k8ssandra.io/tasks/migrate/#pre-requisites) before people start attempting and going all the way to reach this step and fail.

Thanks

[burmanm]

That documentation is wrong. You can use Spec.Cassandra.ClusterName to define the real clustername and keep metadata.name as something that's valid for Kubernetes (such as rgs).