Have a dedicated sub-domain for kas address

Release notes

Omnibus installations of GitLab run the Kubernetes Agent Server (KAS) under the main GitLab domain. To stay consistent with the GitLab chart installation method, we are enabling support for sub-domains to serve KAS on Omnibus installations.

We are not deprecating the previous /-/kubernetes-agent path to access KAS, it will continue to work.

Proposal

Make it possible to setup kas.<gitlab-host> for kas.

In charts gitlab-org/charts/gitlab#2373 (closed), we are shifting to a separate sub-domain for the kas listen address. Support the same for Omnibus but keep the current behavior as the default.

Do we need this for GitLab.com rollout ?

No

Why do we want to do this ?

To match charts, for consistency

/cc @mattkasa @nicholasklick

Edited by Mikhail Mazurskiy