GitHub Actions: CI/CD Pipeline Simply Explained

GitHub Actions: CI/CD for Beginners

GitHub Actions automates your entire software development process. Builds, tests, deployments – all directly in GitHub. This guide shows you how to get started.

What is CI/CD?

Continuous Integration (CI): Automatic building and testing on every push.

Continuous Deployment (CD): Automatic deployment after successful tests.

Benefits:

• Catch errors early
• Consistent builds
• Faster releases
• Less manual work

Your First Workflow

Create .github/workflows/ci.yml:

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name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Run tests
        run: npm test

What's happening here?

• Triggered on push and pull request to main
• Ubuntu runner is started
• Repository is checked out
• Node.js is installed
• Dependencies are installed
• Tests are executed

Understanding Workflow Syntax

Triggers (on)

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on:
  # On every push
  push:

  # Only specific branches
  push:
    branches: [main, develop]

  # On tags
  push:
    tags: ['v*']

  # Pull Requests
  pull_request:
    branches: [main]

  # Scheduled (Cron)
  schedule:
    - cron: '0 0 * * *'  # Daily at midnight

  # Manually triggerable
  workflow_dispatch:

  # On release
  release:
    types: [published]

Jobs and Steps

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jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Step 1
        run: echo "Hello"

  test:
    runs-on: ubuntu-latest
    needs: build  # Waits for build
    steps:
      - name: Step 1
        run: echo "Testing"

  deploy:
    runs-on: ubuntu-latest
    needs: [build, test]  # Waits for both
    if: github.ref == 'refs/heads/main'
    steps:
      - name: Deploy
        run: echo "Deploying"

Practical Examples

Node.js Project with Tests

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name: Node.js CI

on:
  push:
    branches: [main]
  pull_request:

jobs:
  test:
    runs-on: ubuntu-latest

    strategy:
      matrix:
        node-version: [18, 20, 22]

    steps:
      - uses: actions/checkout@v4

      - name: Use Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}
          cache: 'npm'

      - run: npm ci
      - run: npm run build --if-present
      - run: npm test

  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npm run lint

Python with pytest

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name: Python CI

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.11'
          cache: 'pip'

      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install -r requirements.txt
          pip install pytest pytest-cov

      - name: Run tests with coverage
        run: pytest --cov=src --cov-report=xml

      - name: Upload coverage
        uses: codecov/codecov-action@v4
        with:
          file: ./coverage.xml

Docker Build and Push

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name: Docker

on:
  push:
    branches: [main]
    tags: ['v*']

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: |
            username/app:latest
            username/app:${{ github.sha }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

Deployment to Vercel

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name: Deploy to Vercel

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Deploy to Vercel
        uses: amondnet/vercel-action@v25
        with:
          vercel-token: ${{ secrets.VERCEL_TOKEN }}
          vercel-org-id: ${{ secrets.VERCEL_ORG_ID }}
          vercel-project-id: ${{ secrets.VERCEL_PROJECT_ID }}
          vercel-args: '--prod'

Deployment to Server via SSH

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name: Deploy to Server

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Deploy via SSH
        uses: appleboy/ssh-action@v1.0.0
        with:
          host: ${{ secrets.SERVER_HOST }}
          username: ${{ secrets.SERVER_USER }}
          key: ${{ secrets.SSH_PRIVATE_KEY }}
          script: |
            cd /var/www/app
            git pull origin main
            npm ci
            npm run build
            pm2 restart app

Secrets and Environment Variables

Setting Up Secrets

Repository → Settings → Secrets and variables → Actions → New repository secret

Using Secrets

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steps:
  - name: Use secret
    env:
      API_KEY: ${{ secrets.API_KEY }}
    run: |
      curl -H "Authorization: Bearer $API_KEY" https://api.example.com

Environment-Specific Secrets

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jobs:
  deploy:
    runs-on: ubuntu-latest
    environment: production  # Uses production secrets

    steps:
      - name: Deploy
        env:
          DATABASE_URL: ${{ secrets.DATABASE_URL }}
        run: ./deploy.sh

Caching for Faster Builds

npm Cache

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- uses: actions/setup-node@v4
  with:
    node-version: '20'
    cache: 'npm'  # Automatic caching!

Manual Caching

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- name: Cache dependencies
  uses: actions/cache@v4
  with:
    path: ~/.cache/pip
    key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt') }}
    restore-keys: |
      ${{ runner.os }}-pip-

Storing Artifacts

Upload Build Artifacts

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- name: Build
  run: npm run build

- name: Upload artifact
  uses: actions/upload-artifact@v4
  with:
    name: build
    path: dist/
    retention-days: 5

Use Artifacts in Another Job

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jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - run: npm run build
      - uses: actions/upload-artifact@v4
        with:
          name: build
          path: dist/

  deploy:
    needs: build
    runs-on: ubuntu-latest
    steps:
      - uses: actions/download-artifact@v4
        with:
          name: build
          path: dist/
      - run: ./deploy.sh

Matrix Builds

Test on multiple platforms/versions simultaneously:

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jobs:
  test:
    runs-on: ${{ matrix.os }}

    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
        node: [18, 20, 22]
        exclude:
          - os: macos-latest
            node: 18

    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node }}
      - run: npm test

Conditional Execution

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jobs:
  deploy:
    if: github.event_name == 'push' && github.ref == 'refs/heads/main'

  notify:
    if: failure()  # Only on failure
    needs: [build, test]

Reusable Workflows

Define Workflow

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# .github/workflows/reusable-test.yml
name: Reusable Test Workflow

on:
  workflow_call:
    inputs:
      node-version:
        required: true
        type: string

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ inputs.node-version }}
      - run: npm ci && npm test

Call Workflow

yamlCopy
# .github/workflows/ci.yml
name: CI

on: [push]

jobs:
  test:
    uses: ./.github/workflows/reusable-test.yml
    with:
      node-version: '20'

Troubleshooting and Debugging

Enable Debug Logging

Repository → Settings → Secrets → Add:

• ACTIONS_RUNNER_DEBUG = true
• ACTIONS_STEP_DEBUG = true

Local Testing with act

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# Install act (macOS)
brew install act

# Run workflow locally
act push

Best Practices

1. Use caching – Saves build time
2. Never hardcode secrets – Always use Repository Secrets
3. Limit concurrency – Prevents parallel deployments
4. Set timeout – Stops hanging jobs
5. Use specific versions – @v4 instead of @latest

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jobs:
  deploy:
    runs-on: ubuntu-latest
    timeout-minutes: 10
    concurrency:
      group: production
      cancel-in-progress: false

Conclusion

GitHub Actions is a powerful CI/CD tool integrated directly into GitHub. Start with simple workflows and expand gradually.

For more complex DevOps requirements, Balane Tech is happy to help you set up professional CI/CD pipelines.