GitHub Actions - CI/CD Pipelines

GitHub Actions allows you to create workflows that are triggered by events in your repository, like a push, a pull_request, or even a manual trigger.

1. The Workflow File

Workflows are defined in YAML files inside the .github/workflows/ directory.

example-workflow.yaml:

name: CI Pipeline
 
on:
  push:
    branches: [ main ]
 
jobs:
  build-and-test:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3
 
      - name: Set up Python
        uses: actions/setup-python@v4
        with:
          python-version: '3.9'
 
      - name: Install dependencies
        run: pip install -r requirements.txt
 
      - name: Run tests
        run: pytest

2. Running the Workflow

Trigger the Action

Action:

git add .
git commit -m "feat: add ci pipeline"
git push origin main

Check the Result

Result: Go to the Actions tab in your GitHub repository. You will see a live log:

✓ Checkout code
✓ Set up Python
✓ Install dependencies
✓ Run tests
  - pytest results: 12 passed, 0 failed
Workflow Status: Success

3. GitHub Actions Terminology

Term	Description
Workflow	The automated process (the YAML file).
Event	What triggers the workflow (e.g., `push`).
Job	A set of steps that run on the same runner.
Step	An individual task (running a script or an Action).
Action	A reusable application (e.g., `actions/checkout`).
Runner	The server that executes the workflow (e.g., `ubuntu-latest`).

4. Using Secrets

You should never put passwords or API keys in your YAML. Use GitHub Secrets.

Action (Manifest snippet):

      - name: Deploy to Production
        env:
          API_KEY: ${{ secrets.PROD_API_KEY }}
        run: ./deploy.sh

Summary

YAML based: Workflows live in your repo.
Event driven: Push, PR, or Cron.
Reusable: Use community actions from the GitHub Marketplace.
Free for Public Repos: Great for open source and small teams.