Deploy the GitHub runner charm for the first time

What you’ll do

• Setup a GitHub repository
• Activate the GitHub APIs related to self-hosted runner
• Deploy the GitHub runner charm
• Ensure GitHub repository setting are secure
• Run a simple workflow on the self-hosted runner

Requirements

• GitHub Account.
• Juju 3 installed.
• Juju controller on OpenStack or LXD (see How to run on LXD cloud).

For more information about how to install and use Juju, see Get started with Juju.

Steps

Create GitHub repository

The GitHub self-hosted runner spawned by the charm needs to connect to a GitHub repository or organization. GitHub repositories are used as it is simpler to manage.

To create a GitHub repository, log in to GitHub with your GitHub Account and follow the instructions here. For this tutorial, create a public repository as GitHub branch protection rules is only available in public repository with GitHub Free tier.

Activate GitHub APIs related to self-hosted runner

This must be done for the GitHub runner charm to function correctly.

The GitHub runner charm relies on GitHub APIs for self-hosted runners. Some of the APIs will only be functional after a self-hosted runner registration token is requested for the repository for the first time.

The registration token can be requested by calling the GitHub API. Alternatively, it can also be requested by visiting the “New self-hosted runner” page for the repository (https://github.com/{OWNER}/{REPO}/settings/actions/runners/new). This can be done by following the instruction to the 4th step provided here.

Set up the tutorial model

To easily clean up the resources and to separate your workload from the contents of this tutorial, set up a new Juju model with the following command.

juju add-model github-runner-tutorial

Deploy the GitHub runner charm

The charm requires a GitHub personal access token with repo access, which can be created following the instructions here. A user with admin access for the repository/org is required, otherwise, the repo-policy-compliance will fail the job. For information on token scopes, see How to change GitHub personal access token.

Once the personal access token is created, the charm can be deployed with:

juju deploy github-runner --constraints="cores=4 mem=16G root-disk=20G virt-type=virtual-machine" --config token=<TOKEN> --config path=<OWNER/REPO> --config runner-storage=memory --config vm-memory=2GiB --config vm-disk=10GiB

Replacing the <TOKEN> with the personal access token, and <OWNER/REPO> the GitHub account name and GitHub repository separated with /.

The --constraints option for the juju deploy sets the resource requirements for the Juju machine hosting the charm application. This is used to accommodate different sizes of self-hosted runners. For details, refer to Managing resource usage.

The --storage option mounts a juju storage to be used as the disk for LXD instances hosting the self-hosted runners. Refer How to configure runner storage for more information.

The charm performs various installation and configuration on startup. The charm might upgrade the kernel of the Juju machine and reboot the Juju machine. During reboot, the Juju machine will go into the down state; this is a part of the normal reboot process and the Juju machine should be restarted after a while.

Monitor the deployment status using juju status --watch 5s. The deployment finishes when the status shows “Active”.

Once the charm reaches active status, visit the runner page for the GitHub repository (https://github.com/{OWNER}/{REPO}/settings/actions/runners) according to the instructions here. A single new runner should be available as it is the default number of self-hosted runners created.

The charm will spawn new runners on a schedule. During this time, the charm will enter maintenance status.

Run a simple workflow on the self-hosted runner

Once the self-hosted runner is available on GitHub, it can be used to run GitHub Actions jobs similar to runners provided by GitHub. The only difference being the label specified in the runs-on of a job.

In addition to the labels added by the GitHub runner application by default, the charm will include labels from the labels charm configuration.

To test out the self-hosted runner, create the following file under the path .github/workflows/runner_test.yaml in the repository with the following content:

name: Runner test

on:
  push:

jobs:
  hello-world-test:
    runs-on: [self-hosted]
    steps:
        - run: echo "hello world"

Upon pushing the changes, under the Actions tab of the GitHub repository, the workflow run should appear after a while. The workflow should complete successfully.

If the workflow failed at the Set up runner step with the following message:

This job has failed to pass a repository policy compliance check as defined in the GitHub - canonical/repo-policy-compliance: repo-policy-compliance - charm repository. repository. The specific failure is listed below. Please update the settings on this project to fix the relevant policy.

The repository setting does not comply with the best practice enforce by the charm. See How to comply with repository policies.

Clean up the environment

The Juju model, charm and the self-hosted runners can be removed with the following command:

juju destroy-model --destroy-storage github-runner-tutorial