Docker Image Requirements for a GitLab-CI Runner

Question

I have GitLab, GitLab-CI and gitlab-ci-multi-runner running on different machines. I've successfully added a runner using docker and the ruby:2.1 image as detailed on https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/blob/master/docs/install/linux-repository.md

What I'd like to do next is have runners for a minimal Ubuntu 12.04, 14.04 configured. Not knowing docker, I thought I'd try to use the ubuntu:14.04 and ubuntu:12.04 images. However when the start up and try to clone my project repo, they complain about git not being found. I then assumed that with these images, git wasn't installed. So my questions are:

• What tools need to be available in a docker image to be used "out-of-the-box" by the gitlab-ci-multi-runner
• Are there a set of images already available for various OS's with these already included
• Should I really be looking to create my own docker images for this purpose?

Answer 1

Popular base images that contain commonly used software for building software are (based on) buildpack-deps https://hub.docker.com/r/library/buildpack-deps/ (eg openjdk is based on that)

In your case you could specify FROM buildpack-deps:stretch-scm which is based on Debian Stretch and includes source code management (SCM) tools like git.

I suppose you could create a Gitlab Runner that uses these images as default. But I think you should always specify the needed image in your .gitlab-ci.yml -file .

I would always hesitate in creating my own Docker Images , because there are a lot available . Still many specific ones are maintained (or better not maintained) by one person for a specific use case that often does not fit your application. The best choice would be to pick a base -image and only add minor RUN commands for the customization.