Runners are the agents that run the CI/CD jobs that come from GitLab. When you register a runner, you are setting up communication between your GitLab instance and the machine where GitLab Runner is installed. Runners usually process jobs on the same machine where you installed GitLab Runner.

What is a runner in GitLab?

Runners are the agents that run the CI/CD jobs that come from GitLab. When you register a runner, you are setting up communication between your GitLab instance and the machine where GitLab Runner is installed. Runners usually process jobs on the same machine where you installed GitLab Runner.

How does GitLab choose a runner?

Update to answer comments: Runners communicate through the CI API to get build status. This will eventually imply that it will become a more or less random choosing of the runner based on when it finished the last job and the x amount of ms it is waiting to check.