Understanding Ephemeral Runners in GitHub Actions

1. Introduction

Ephemeral runners in GitHub Actions are temporary virtual environments that can be used to run jobs in your workflows. They are created and destroyed dynamically, providing a clean slate for each job run.

2. Key Concepts

3. Setting Up Ephemeral Runners

To use ephemeral runners in your GitHub Actions workflow, you need to specify the type of runner you want to use in your workflow YAML file. Here's a step-by-step guide:

1. Open your repository on GitHub.

2. Navigate to the Actions tab.

3. Create a new workflow file (e.g., .github/workflows/ci.yml).

4. Define the workflow and specify the runner type:

   name: CI
   
   on: [push]
   
   jobs:
     build:
       runs-on: ubuntu-latest  # This specifies that an ephemeral runner on GitHub-hosted Ubuntu should be used
       steps:
       - uses: actions/checkout@v2
       - name: Run a one-line script
         run: echo Hello, world!

5. Commit the workflow file to trigger the action.

4. Best Practices

• Use GitHub-hosted runners for a temporary and hassle-free setup.
• Keep your workflows modular to improve reusability and maintainability.
• Regularly review and optimize your workflow to reduce build times.
• Utilize caching to speed up repeated jobs.

5. FAQ