Using Podman to power your Gitlab CI pipeline

1. Installation and Setup
   1. Installing the gitlab-runner
   2. Setting up a Runner Instance
2. Tweaking the Installation
3. License
4. Links

Installation and Setup

The install instructions are for a Fedora 31+ installation. Most of the instructions should transfer to other distributions. gitlab-runner needs to be installed in version 12.6 or higher, because we rely on the image tag being exposed from the .gitlab-ci.yml file.

Installing the gitlab-runner

First, you need to install the gitlab-runner using the instructions listed on the website. You can silence the SELinux warnings, by labelling the binary with the proper bin_t type like:

sudo chcon -t bin_t /usr/bin/gitlab-runner

Ensure that the gitlab-runner service runs with the appropirate permissions. Since we are using Podman in a rootless setup, we can run the service with user privileges instead of root permissions. Edit the service file (/etc/systemd/system/gitlab-runner.service) and add the User and Group lines in the service section.

[Service]
User=gitlab-runner
Group=gitlab-runner

Note: This step has to be re-done on every update of the gitlab-runner package, since it overwrites the modifications to the service file. This is because the package places the service file into the wrong directory.

Setting up a Runner Instance

As the gitlab-runner user change into the home directory (/home/gitlab-runner) and clone this repository.

git clone https://github.com/jonasbb/podman-gitlab-runner

Then follow the instructions to set up a new runner instance:

sudo -u gitlab-runner gitlab-runner register \
    --url https://my.gitlab.instance/ \
    --registration-token $GITLAB_REGISTRATION_TOKEN \
    --name "Podman Runner" \
    --executor custom \
    --builds-dir /home/user \
    --cache-dir /home/user/cache \
    --custom-prepare-exec "/home/gitlab-runner/prepare.sh" \
    --custom-run-exec "/home/gitlab-runner/run.sh" \
    --custom-cleanup-exec "/home/gitlab-runner/cleanup.sh"

Tweaking the Installation

Currently, the scripts do not provide much customization. However, you can adapt the functions start_container and install_dependencies to specify how Podman should spawn the containers and how to install the dependencies.

Some behaviour can be tweaked by tweaked by setting the correct environment variables. Rename the custom_base.template.sh file into custom_base.sh to make use of the customization. The following variables are supported right now:

• PODMAN_RUN_ARGS: Customize how Podman spawns the containers.

Podman supports access to private Gitlab registries. You can set the DOCKER_AUTH_CONFIG variable under Settings → CI / CD and provide the credentials for accessing the private registry. Details how the variable has to look can be found under using statically defined credentials in the Gitlab documentation.

License

Licensed under the MIT license.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Links

• https://tech.immerda.ch/2019/10/gitlab-ci-with-podman/
  First source describing how to set up Podman and gitlab-runner and the source for these scripts.
• https://docs.gitlab.com/runner/executors/custom.html
  Official documentation about the custom executor feature for Gitlab CI.
• https://docs.gitlab.com/runner/executors/custom_examples/
  Official examples how to use the custom executor feature.