Rancher & gitlab-runner - is there a way to get the gitlab-runner to tell Rancher to start the CI test environment instead?

Question

I’ve got an AWS gitlab instance successfully doing CI with gitlab-runners running under vagrant on my local dev machine. I’d like to move the runners off my machine and onto a standalone server...

I’ve put Rancher on a box and can get the gitlab runner installed, but I can’t get my head around how to not do docker-in-docker, or whether this actually matters.

My understanding is that unless I do _some_configuration_I_don’t_know_ that Rancher runs the gitlab-runner as a Docker container, and the gitlab runner will in turn start a docker container inside itself to run my CI test environment as specified in the .gitlab-ci.yml

Is there a way to get the gitlab-runner to tell Rancher to start the CI test environment instead?

Answer 1

The short answer is "it depends". Rancher itself runs using system-docker and the docker instances it starts for you, such as gitlab-runner are run separately in regular docker. Gitlab-runner then will start runners depending on its configuration:

There are three methods to enable the use of... docker run during jobs; each with their own tradeoffs.

https://docs.gitlab.com/ee/ci/docker/using_docker_build.html#runner-configuration

My eventual solution

I'd initially installed Rancher 1.6 and just couldn't get the dependencies working (Rancher OS running Rancher 1.6 and Rancher agent running on a couple of Alpine nodes).

The upgrade to Rancher v2 was a steep learning curve as you need to learn the Kubernetes ecosystem tooling (helm, kubectl, etc). I still couldn't get a gitlab-runner working under Rancher v2, but upgrading to v2.0.8 fixed it. I could add the custom helm chart for gitlab-runner and after cribbing the settings from https://gitlab.com/charts/gitlab-runner/blob/master/values.yaml I could get gitlab-runner working under Rancher v2.