Feature Request: Use underscores (`_`) in cluster names

[joewreschnig]

Cluster names currently seem to be restricted to [A-Za-z0-9-]. Unfortunately, our cluster names use _ as a separator, which I think is also idiomatic in ClickHouse cluster naming.

I guess this is due to using the cluster name as part of the Kubernetes resource names, which can't use _. But even if I try providing my own service/pod templates that use {clusterID} instead, it still refuses to create the resources.

Assuming I'm not missing or misunderstanding anything - Would it be possible to introduce a new configuration field e.g. systemClusterName to configure specifically the cluster's name within ClickHouse's config, separate from the Kubernetes resource name, which defaults to the regular name when unset?

[alex-zaitsev]

Looks like a corner case but it is possible to do. cc @sunsingerus