I have a very simple .gitlab-ci.yml file:
build-job:
stage: build
script:
- echo "Hello, $GITLAB_USER_LOGIN!"
And run this pipeline. It uses a shared gitlab runner.
The job executed in a docker container. But we haven't mentioned docker executor for gitlab runner and also any image. So how is this whole thing done?
Running your CI/CD jobs in Docker containers implies to Register a runner so that all jobs run in Docker containers.
But if you are using GitLab SaaS (GitLab.com), your CI jobs automatically run on runners in the GitLab Build Cloud.
With a Linux runner, that means n1-standard-1 instances with 3.75GB of RAM, CoreOS and the latest Docker Engine installed.