Provide runner as a Docker Image

[WtfJoke]

Describe the enhancement
Is it possible for you to provide official docker images for letting a runner run?

Additional information
We want to use self hosted runner, but we dont want to maintain machines/vms so it would be cool to have a ready to run official docker image in order to use them in services like aws fargate/azure container instances.

If im wrong here and I should have opened a topic in the github actions community forum please let me know and feel free to close the issue/feature request.

[vincentbrison]

Some example of runner as a Docker image:

• https://github.com/tcardonne/docker-github-runner
• https://github.com/myoung34/docker-github-actions-runner
• https://github.com/joeyx22lm/docker-github-actions-runner

Additionally, Runner running in Docker is not able to use Docker itself:

runner/src/Runner.Worker/ContainerOperationProvider.cs

Line 68 in f9b5d62

throw new NotSupportedException("Container feature is not supported when runner is already running inside container.");

This is a major downside, as we can not yet manage self hosted runners with Kubernetes for example, as we have to manage VMs or real machines.

[WtfJoke]

Thank you @vincentbrison for providing these examples, I found a couple of them as well, but I am not sure if we are allowed to use them in our company (we have a restriction to use only official images). Thats the reason why I asked here. :)

The hint about docker in docker is useful (a couple of application suffer of this problem). 👍

[ppamorim]

I don't understand this limitation, what's the difference between this and a VM running in the machine? We are using M1 machines as our hosts and since the native runner on macOS does not support containers, we decided to use Docker, but when executing it, we get this error.

[scolastico]

Also its possible with docker to run a docker conatiner in a docker container.
You only need to mount the docker directory /var/lib/docker in the normal file system so it doesnt gets mounted as an AUFS mountpoint.

This page i found describes a bit better than me: https://www.docker.com/blog/docker-can-now-run-within-docker/

[pdomagala-tl]

@scolastico did you manage to do this?

[scolastico]

not in this way but in another: https://github.com/scolastico-dev/s.RunnerManager

[pdomagala-tl]

are you able to run docker inside the docker container?

[scolastico]

Run docker inside docker: Yes with the link from above (https://www.docker.com/blog/docker-can-now-run-within-docker/).
But my solution from my last comment was not from that. My main problem why i saw that issue was that i wanted clean runner instances for selfhosting and so i developed a small programm which exactly does this. Its starting automatically runners as they are needed and deletes used ones.

[nikola-jokic]

Hey everyone,

There is a bare-minimum runner image available now: ghcr.io/actions/actions-runner:latest
The Dockerfile is available here.

It is now part of the release process (#2250). The idea is to provide an image that can be used by actions-runner-controller, but also as a stand-alone image.

[danm]

hi @nikola-jokic how do you use this image?

docker run ghcr.io/actions/actions-runner:2.300.2 ?

[nikola-jokic]

Hey @danm,

You would need to provide an entrypoint. Keep in mind, the entrypoint should know how to configure and run the runner. The entrypoint by default does not exist. So imperatively, you can provide an --entrypoint with docker run, or you can use this Dockerfile as a base for building your own minimal runner image.

[Spriz]

Hi @nikola-jokic - thanks for providing those Dockerfiles - is there any plans to support docker in docker? We're in the process of migrating from Gitlab CI/CD to Github Actions and it seems quite agressive to run autoscaling VMs compared to running 1-2 dedicated machines that runs 5-10 instances (that are ephemeral) of that container.

Either being able to use docker-in-docker, or having the agent support multiple workspaces on the same VM would both solve this.