github-workflow.yml

GitHub Actions Workflow (Multi-Stage CI/CD)

GitHub Actions allows automation of CI/CD workflows using YAML-based configuration. Below is a detailed multi-stage workflow, including best practices and scenario-based questions.

---

1. Basic Multi-Stage GitHub Actions Workflow

name: CI/CD Pipeline

on:
  push:
    branches:
      - main
  pull_request:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Set up Node.js
        uses: actions/setup-node@v4
        with:
          node-version: 18

      - name: Install Dependencies
        run: npm install

      - name: Run Linter
        run: npm run lint

      - name: Run Tests
        run: npm test

  docker-build:
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

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

      - name: Build and Push Docker Image
        run: |
          docker build -t mydockerhub/myapp:latest .
          docker push mydockerhub/myapp:latest

  deploy:
    runs-on: ubuntu-latest
    needs: docker-build
    environment: production
    if: github.ref == 'refs/heads/main'
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Deploy Application
        run: ./deploy.sh

---

2. Breakdown of Workflow Sections

2.1 on (Triggers)

• Defines when the workflow runs.

• Example: Run on push to main and pull requests:

  on:
    push:
      branches:
        - main
    pull_request:
      branches:
        - main

• Best Practice: Avoid running deployments on pull_request.

---

2.2 Jobs & Dependencies

• jobs define separate execution units.

• needs ensures jobs execute in sequence.

Job	Purpose	Dependency
build	Installs dependencies, runs linter & tests	None
docker-build	Builds and pushes Docker image	build
deploy	Deploys app to production	docker-build

---

2.3 runs-on

• Specifies the runner environment.

  runs-on: ubuntu-latest

• Options:

  • ubuntu-latest, macos-latest, windows-latest

  • Self-hosted runners for private deployments.

---

2.4 Docker Authentication

• Logs in to Docker Hub securely:

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

• Best Practice: Use GitHub Secrets instead of hardcoding credentials.

---

2.5 Conditional Deployment

• Deploy only on main branch:

  if: github.ref == 'refs/heads/main'

• Best Practice: Use environments for different deployments:

  environment: production

---

3. Optimized Multi-Stage GitHub Actions Workflow

name: Optimized CI/CD Pipeline

on:
  push:
    branches:
      - main
  pull_request:

env:
  IMAGE_NAME: myapp
  IMAGE_TAG: latest
  DOCKER_REGISTRY: mydockerhub

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Install Dependencies
        run: npm install

      - name: Run Tests
        run: npm test

  docker-build:
    runs-on: ubuntu-latest
    needs: build
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Build Docker Image
        run: docker build -t $DOCKER_REGISTRY/$IMAGE_NAME:$IMAGE_TAG .

      - name: Push Docker Image
        uses: docker/build-push-action@v5
        with:
          push: true
          tags: ${{ env.DOCKER_REGISTRY }}/${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }}
          secrets: |
            "DOCKER_USERNAME=${{ secrets.DOCKER_USERNAME }}"
            "DOCKER_PASSWORD=${{ secrets.DOCKER_PASSWORD }}"

  deploy:
    runs-on: ubuntu-latest
    needs: docker-build
    environment: production
    if: github.ref == 'refs/heads/main'
    steps:
      - name: Checkout Code
        uses: actions/checkout@v4

      - name: Deploy to Server
        run: ./deploy.sh

---

4. GitHub Actions Best Practices

✅ Use Caching for Faster Builds

- name: Cache Dependencies
  uses: actions/cache@v4
  with:
    path: ~/.npm
    key: npm-${{ runner.os }}-${{ hashFiles('package-lock.json') }}

✅ Use Matrix Builds for Parallel Execution

strategy:
  matrix:
    node-version: [16, 18, 20]

✅ Use Encrypted Secrets for Credentials

secrets: |
  "DOCKER_USERNAME=${{ secrets.DOCKER_USERNAME }}"
  "DOCKER_PASSWORD=${{ secrets.DOCKER_PASSWORD }}"

✅ Run Linter & Tests Before Deployment

- name: Run ESLint
  run: npm run lint

✅ Use if: for Conditional Execution

if: github.ref == 'refs/heads/main'

---

5. Scenario-Based Interview Questions

Q1: How do you prevent a deployment on pull requests?

Answer: Use if: github.ref == 'refs/heads/main'

if: github.ref == 'refs/heads/main'

---

Q2: How can you cache dependencies in GitHub Actions?

Answer: Use actions/cache

- name: Cache Dependencies
  uses: actions/cache@v4
  with:
    path: ~/.npm
    key: npm-${{ runner.os }}-${{ hashFiles('package-lock.json') }}

---

Q3: How do you securely store API keys in GitHub Actions?

Answer: Use GitHub Secrets

secrets: |
  "API_KEY=${{ secrets.API_KEY }}"

---

Q4: How do you ensure that only the main branch can deploy to production?

Answer: Use if: condition with github.ref

if: github.ref == 'refs/heads/main'

---

6. Summary

Topic	Key Takeaways
Triggers (on)	Defines when workflows run (push, pull_request)
Jobs (jobs)	Independent tasks executed in sequence or parallel
Secrets	Store credentials securely
Parallel Execution	Use matrix to test multiple environments
Docker Caching	Use actions/cache to speed up builds
Conditional Execution	Use if: to control execution

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This GitHub Actions CI/CD guide covers best practices, optimizations, and interview questions! 🚀 Let me know if you need more details. 😊