How to Set Up Continuous Deployment for a NestJS Application Using Docker

In today’s fast-paced software development environment, continuous deployment (CD) has become a cornerstone practice for maintaining agility and ensuring high-quality software delivery. If you're developing a NestJS application, integrating Docker into your deployment pipeline can streamline your workflow and enhance your productivity. In this guide, we will explore how to set up continuous deployment for a NestJS application using Docker, providing you with actionable insights, clear code examples, and step-by-step instructions.

What is Continuous Deployment?

Continuous deployment is a software development practice where code changes are automatically deployed to production after passing automated tests. This approach minimizes the manual steps in the deployment process, allowing teams to deliver new features, bug fixes, and improvements to users rapidly and reliably.

Benefits of Continuous Deployment

• Faster Release Cycles: By automating the deployment process, you can release updates to production quickly and frequently.
• Improved Code Quality: Continuous testing ensures that only code that meets quality standards is deployed.
• Reduced Risk: Smaller, incremental updates make it easier to identify issues and roll back changes if necessary.

Why Use Docker for Deployment?

Docker is a popular platform for building, shipping, and running applications in containers. Here’s why you should use Docker for deploying your NestJS application:

• Environment Consistency: Docker ensures that your application runs in the same environment regardless of where it is deployed.
• Isolation: Each application runs in its own container, preventing conflicts with other applications.
• Scalability: Docker containers can be easily scaled up or down based on demand.

Prerequisites

Before diving into the setup, ensure you have the following prerequisites:

1. Node.js: Version 14 or higher installed.
2. NestJS CLI: Installed globally using npm install -g @nestjs/cli.
3. Docker: Installed and running on your machine.
4. Git: To manage your codebase.

Step-by-Step Guide to Setting Up Continuous Deployment

Step 1: Create Your NestJS Application

If you haven’t already created a NestJS application, you can do so with the following command:

nest new my-nest-app

Navigate to your application directory:

cd my-nest-app

Step 2: Create a Dockerfile

In your application root directory, create a file named Dockerfile to define how your application will be built and run in a Docker container. Here’s a sample Dockerfile:

# Use the official Node.js image as the base image
FROM node:14

# Set the working directory
WORKDIR /usr/src/app

# Copy package.json and package-lock.json
COPY package*.json ./

# Install dependencies
RUN npm install

# Copy the rest of the application code
COPY . .

# Build the NestJS application
RUN npm run build

# Expose the application port
EXPOSE 3000

# Command to run the application
CMD ["node", "dist/main"]

Step 3: Create a .dockerignore File

To prevent unnecessary files from being included in your Docker image, create a .dockerignore file:

node_modules
dist
npm-debug.log
Dockerfile
.dockerignore

Step 4: Set Up Continuous Integration

To implement continuous deployment effectively, you need a CI/CD platform. For this guide, we'll use GitHub Actions. Create a .github/workflows/deploy.yml file in your repository:

name: Deploy to Docker

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Node.js
        uses: actions/setup-node@v2
        with:
          node-version: '14'

      - name: Install dependencies
        run: npm install

      - name: Build the application
        run: npm run build

      - name: Build Docker image
        run: |
          docker build -t my-nest-app .

      - name: Push Docker image
        run: |
          echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
          docker tag my-nest-app:latest my-docker-repo/my-nest-app:latest
          docker push my-docker-repo/my-nest-app:latest

Step 5: Configure Secrets in GitHub

To ensure your Docker credentials are secure, add the following secrets to your GitHub repository:

• DOCKER_USERNAME: Your Docker Hub username.
• DOCKER_PASSWORD: Your Docker Hub password.

Step 6: Deploy Your Application

Now that you have set up your CI/CD pipeline, every time you push changes to the main branch, GitHub Actions will automatically build your Docker image and push it to your Docker Hub repository.

Step 7: Run Your Docker Container

To run your Docker container, use the following command:

docker run -d -p 3000:3000 my-docker-repo/my-nest-app:latest

Troubleshooting Tips

• Failed Builds: Check the logs in GitHub Actions to identify any errors during the build process.
• Container Not Starting: Ensure that your application is set to listen on the correct port and that it is properly exposed in your Dockerfile.

Conclusion

Setting up continuous deployment for a NestJS application using Docker can significantly enhance your development workflow, enabling faster and more reliable software delivery. By following the steps outlined in this guide, you can implement an efficient CI/CD pipeline that leverages the power of Docker. This not only simplifies your deployment process but also helps maintain the overall health of your application. Happy coding!