Introduction:

Welcome back to Day 2 of my 90-day DevOps journey! Inspired by my experience in the @SheCodeAfrica mentorship program, today we'll dive into automating the deployment of a Dockerized web application using GitHub Actions. This guide aims to simplify CI/CD processes, making application deployments more efficient and reliable.

What You'll Learn:

• Building a Dockerized Node.js application.
• Setting up GitHub Actions for automating Docker image builds and deployments.
• Overcoming challenges encountered during setup.

Prerequisites:

Before we begin, ensure you have:

• Basic understanding of Docker and GitHub (refer to my previous articles if needed).
• A GitHub account for repository hosting.
• Docker installed on your local machine for testing.

Step-by-Step Guide: Automating Dockerized Application Deployment with GitHub Actions

Step 1: Prepare Your Dockerized Application

1. Create Your Application:

   • Start by creating a simple Node.js application. Navigate to your terminal and execute:

    mkdir my-docker-app
    cd my-docker-app
   

2. Initialize Git Repository:

   • Initialize Git for version control:

    git init
   

3. Write Your Application Code:

   • Create a basic Node.js application. For example, create an app.js file:

   app.js:
   

    const http = require('http');
   
    const hostname = '0.0.0.0';
    const port = 3000;
   
    const server = http.createServer((req, res) => {
      res.statusCode = 200;
      res.setHeader('Content-Type', 'text/plain');
      res.end('Hello, World!\n');
    });
   
    server.listen(port, hostname, () => {
      console.log(`Server running at http://${hostname}:${port}/`);
    });
   

4. Create a Dockerfile:

   • Define a Dockerfile in the project root:

   Dockerfile:
   

    FROM node:14
   
    WORKDIR /app
   
    COPY package*.json ./
    RUN npm install
   
    COPY . .
   
    EXPOSE 3000
   
    CMD ["node", "app.js"]
   

5. Test Locally:

   • Build and run your Docker container locally:

    docker build -t my-docker-app .
    docker run -p 3000:3000 my-docker-app
   

• Open http://localhost:3000 in your browser to verify the application works.

Step 2: Set Up GitHub Repository

1. Create a GitHub Repository:

   • Visit GitHub and create a new repository (my-docker-app).

2. Push Your Code:

   • Push your local Git repository to GitHub:

    git remote add origin <repository-url>
    git add .
    git commit -m "Initial commit"
    git branch -M main
    git push -u origin main
   

Step 3: Configure GitHub Actions Workflow

1. Create a Workflow File:

   • Inside .github/workflows, create docker-build-deploy.yml:

   docker-build-deploy.yml:
   

    name: Docker Build & Deploy
   
    on:
      push:
        branches:
          - main
   
    jobs:
      build-and-deploy:
        runs-on: ubuntu-latest
        steps:
          - name: Checkout Repository
            uses: actions/checkout@v2
   
          - name: Login to Docker Hub
            uses: docker/login-action@v2
            with:
              username: ${{ secrets.DOCKER_USERNAME }}
              password: ${{ secrets.DOCKER_PASSWORD }}
   
          - name: Build and Push Docker Image
            run: |
              docker build -t ${{ secrets.DOCKER_USERNAME }}/my-docker-app:latest .
              docker push ${{ secrets.DOCKER_USERNAME }}/my-docker-app:latest
   
          - name: Deploy Docker Container
            run: |
              docker run -d -p 80:3000 --name my-docker-app ${{ secrets.DOCKER_USERNAME }}/my-docker-app:latest
   

2. Add GitHub Secrets:

   • Go to your GitHub repository > Settings > Secrets.
   • Add Docker Hub credentials (DOCKER_USERNAME and DOCKER_PASSWORD).

Challenges Faced and Solutions:

• Port Already Allocated: During testing, encountering a "port already allocated" error due to a previous Docker container using the same port. This was resolved by stopping the previous container (docker stop <container-id>) or specifying a different port during container deployment.

Recommended Resources for Beginners:

• Docker Basics: Get Started with Docker
• GitHub Actions: Explore GitHub Actions Documentation

Conclusion:

Congratulations on completing Day 2 of our DevOps journey! You've automated Dockerized application deployment with GitHub Actions, improving your CI/CD pipeline skills. Stay tuned for more articles as we explore some more.

See you on Day 3!