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Containerizing a NestJS App with Docker

Docker is a popular platform for building, shipping, and running applications in containers. Containerizing your NestJS application can simplify deployment, improve portability, and ensure consistent behavior across different environments. Here's a step-by-step guide on how to containerize a NestJS app with Docker.

Prerequisites​

  • NestJS app
  • Docker installed on your machine

Step 1: Create a Dockerfile​

In the root directory of your NestJS project, create a new file named Dockerfile with the following content:

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

# Set the working directory in the container
WORKDIR /app

# Copy package.json and package-lock.json to the working directory
COPY package*.json ./

# Install project dependencies
RUN npm install

# Copy the entire project to the working directory
COPY . .

# Build the NestJS app
RUN npm run build

# Expose the port your NestJS app listens on (replace 3000 with your port)
EXPOSE 3000

# Start the NestJS app
CMD ["npm", "run", "start:prod"]

This Dockerfile uses the official Node.js image as the base image, copies the project files, installs dependencies, builds the NestJS app, and finally runs the app in production mode.

Step 2: Build the Docker Image​

In the same directory as the Dockerfile, open a terminal and run the following command to build the Docker image:

docker build -t my-nestjs-app .

Replace my-nestjs-app with a name of your choice for the Docker image.

Step 3: Run the Docker Container​

After the image is built successfully, you can run a Docker container based on the image:

docker run -p 3000:3000 my-nestjs-app

This command maps the container's port 3000 (or the port your NestJS app listens on) to the host's port 3000. You can replace 3000 with your desired port if needed.

Step 4: Access the NestJS App​

Once the container is running, you should be able to access your NestJS app at http://localhost:3000 (or the port you mapped in the previous step).

Additional Configurations​

Environment Variables​

If your NestJS app requires environment variables, you can pass them to the Docker container using the -e or --env flag:

docker run -p 3000:3000 -e APP_ENV=production my-nestjs-app

Persistent Data​

If your NestJS app uses a database or needs to store persistent data, you can mount a volume to the container:

docker run -p 3000:3000 -v /path/to/data:/app/data my-nestjs-app

Replace /path/to/data with the path to the directory you want to mount on your host machine, and /app/data with the path inside the container where the data should be stored.

Conclusion​

By following these steps, you've successfully containerized your NestJS application with Docker. This approach simplifies deployment, ensures consistent behavior across environments, and makes it easier to scale your application as needed.