ADDITIONAL_HOSTS stopped working, showing "503 Service Temporarily Unavailable"

Instead of seeing the OK response from the container via the domain assigned in ADDITIONAL_HOSTS as usual, now we’ve started seeing
“503 Service Temporarily Unavailable
nginx/1.17.10”

The automatically generated domain by Kubernetes continues working however.

The additional hosts domain points as CNAME to currently working domain
Any ideas?

  • What version are you on? Are you using self-managed or GitLab.com?
    • *GitLab (Hint: /help): gitlab.com
    • *Runner (Hint: /admin/runners):kubernetes runners, latest version

Deleting and recreating the cluster has solved the problem