KAS should be reachable on a subdomain of Gitlab (frontend)

Summary

For the user_access features (most importantly the new Dashboard for Kubernetes) it is required to host KAS either on the same domain as GitLab or under a subdomain. However, the default of the Chart hosts KAS on a sibling domain.

For example when configuring global.hosts.domain to example.com then GitLab is hosted on gilab.example.com and KAS is hosted on kas.example.com which doesn't support the aforementioned feature.

The solution would be host KAS by default on kas.gitlab.example.com (like it is for gprd, gstg and other environments).

See Allow KAS and GitLab on different subdomains wh... (gitlab-org/gitlab#416436)

Steps to reproduce

Install Chart with defaults and global.hosts.domain set to example.com (well, must be a domain where you have access to ;))

Configuration used

Just set the global.hosts.domain.

Current behavior

KAS is hosted on kas.example.com when global.hosts.domain set to example.com.

Expected behavior

KAS is hosted on kas.gitlab.example.com when global.hosts.domain set to example.com and GitLab (frontend) would be on gitlab.example.com.

Versions

• Chart: v7.2.3
• Platform:
  • Cloud: (GKE | AKS | EKS | ?)
  • Self-hosted: (OpenShift | Minikube | Rancher RKE | ?)
• Kubernetes: (kubectl version)
  • Client:
  • Server:
• Helm: (helm version)
  • Client:
  • Server:

Relevant logs

n/a

Proposal

• Update charts to set KAS' address to kas.gitlab.example.com when global.hosts.domain set to example.com.
• For new environment, verify that KAS is accessible with the new domain.
• Verify that it does not break existing environments.