OIDC Discovery URL not working when trying to set up Vault with GitLab

Problem

When integration Vault via JWT (formerly done with CI_JOB_TOKEN and endpoint …/jwks) and trying to set up according to the new method (OIDC tokens), I get an error 400 (error checking oidc discovery URL) when trying to put the oidc_discovery_url field into my Vault config (jwt type).

According to the documentation, this should be either https://my_gitlab_instance.de or https://my_gitlab_instance.de/.well-known/oidc-configuration.

Both addresses yield the abovementioned error. The latter gives me a 404 in the browser.

Is there any config which must be additionally done? Or is there any other URL which might work?

Versions

  • Self-managed
  • GitLab v16.11.2-ee (Debian package)
  • free tier