Where do I find a list of software packages included (the pre-installed packages) in Gitlab docker CI images?

I usually use the standard ruby:2.5 image, but I cannot seem to find a list of all packages and softwares/executables that are included in the available build images.

Where is a list of packages included? Or do I always have to test an image in a .gitlab-ci.yml file and see if it works?

(Surely there is a list of packages. Forgive a newbie in the world of CI.)

CodePudding user response：

As mentioned in the GitLab docs: