Series: 30 Days DevOps Interview Preparation

Today’s focus: Building GitHub Actions workflows for Node.js and Python apps, integrating them with AWS for deployment.
This is a must-have skill for DevOps Engineers to automate build, test, and deploy pipelines directly from GitHub.

📖 Theory – What is GitHub Actions?

GitHub Actions is a CI/CD service built into GitHub.
It allows you to:

Automate workflows on push, pull request, or schedule.
Run builds in isolated virtual environments (Linux, macOS, Windows).
Integrate with cloud providers like AWS, Azure, GCP for deployment.
Use secrets to store credentials securely.

🔄 Typical CI/CD Flow for Node.js/Python Apps

Trigger → Checkout → Install Dependencies → Test → Build → Deploy

1️⃣ Trigger: Runs when code changes are pushed.
2️⃣ Checkout: Fetches your repository into the runner.
3️⃣ Setup Environment: Installs the required language version.
4️⃣ Install Dependencies: Installs packages/libraries.
5️⃣ Run Tests: Ensures code quality before deployment.
6️⃣ Build & Deploy: Pushes artifacts to AWS, Docker, or other environments.

🛠 Practical Example – Deploying to AWS EC2

Let’s create a GitHub Actions pipeline for a Node.js app and Python app, deploying to AWS EC2.

1. GitHub Secrets Setup

In your repository:

Go to Settings → Secrets and variables → Actions
Add:
- AWS_ACCESS_KEY_ID
- AWS_SECRET_ACCESS_KEY
- EC2_HOST (Public IP/DNS)
- EC2_USER (e.g., ec2-user)
- EC2_KEY (Base64 encoded SSH private key)

2. Node.js Pipeline (deploy to AWS)

name: Node.js CI/CD

on:
  push:
    branches: [ "main" ]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Setup Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'

    - name: Install dependencies
      run: npm install

    - name: Run tests
      run: npm test

    - name: Deploy to AWS EC2
      env:
        EC2_HOST: ${{ secrets.EC2_HOST }}
        EC2_USER: ${{ secrets.EC2_USER }}
        EC2_KEY: ${{ secrets.EC2_KEY }}
      run: |
        echo "$EC2_KEY" | base64 --decode > ec2_key.pem
        chmod 600 ec2_key.pem
        scp -o StrictHostKeyChecking=no -i ec2_key.pem -r ./* $EC2_USER@$EC2_HOST:/home/$EC2_USER/app
        ssh -o StrictHostKeyChecking=no -i ec2_key.pem $EC2_USER@$EC2_HOST "cd /home/$EC2_USER/app && npm install && pm2 restart all || pm2 start app.js"

3. Python Pipeline (deploy to AWS)

name: Python CI/CD

on:
  push:
    branches: [ "main" ]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Set up Python
      uses: actions/setup-python@v4
      with:
        python-version: '3.10'

    - name: Install dependencies
      run: pip install -r requirements.txt

    - name: Run tests
      run: pytest

    - name: Deploy to AWS EC2
      env:
        EC2_HOST: ${{ secrets.EC2_HOST }}
        EC2_USER: ${{ secrets.EC2_USER }}
        EC2_KEY: ${{ secrets.EC2_KEY }}
      run: |
        echo "$EC2_KEY" | base64 --decode > ec2_key.pem
        chmod 600 ec2_key.pem
        scp -o StrictHostKeyChecking=no -i ec2_key.pem -r ./* $EC2_USER@$EC2_HOST:/home/$EC2_USER/app
        ssh -o StrictHostKeyChecking=no -i ec2_key.pem $EC2_USER@$EC2_HOST "cd /home/$EC2_USER/app && pip install -r requirements.txt && systemctl restart myapp"

💬 Interview Preparation – Key Questions & Answers

Q1: How do you run jobs for multiple versions of Node.js or Python?
➡ Use matrix strategy in GitHub Actions to define multiple versions.

Q2: How do you securely store AWS credentials in GitHub Actions?
➡ Use GitHub Secrets – never hardcode credentials in workflows.

Q3: What’s the difference between a job and a step?
➡ Job = group of steps running on a runner.
➡ Step = individual task inside a job.

Q4: How do you deploy to AWS without exposing private keys?
➡ Use encrypted secrets + Base64 encoding for SSH keys.

Q5: How would you trigger workflow only on the main branch?
➡ Use branches: [ "main" ] under the on section.

✅ Key Takeaways

GitHub Actions integrates directly with your repo, making CI/CD simpler.
Use environment-specific setup for Node.js/Python.
Secrets management is essential for production deployments.
Always test before deployment.

🔗 Follow the series:
💻 GitHub: https://github.com/tathagatgaikwad22/devops-interview-preparation

#DevOps #GitHubActions #Nodejs #Python #AWS #CICD #InterviewPreparation #LearningInPublic #Automation

🚀 Day 12 of 30 Days of DevOps Interview Prep – GitHub Actions: CI/CD Pipeline for Node.js or Python Apps