Docker containerization in NestJS - Mini Project: Build & Apply

Docker containerization with NestJS

📖 Scenario: You are building a simple NestJS application that you want to run inside a Docker container. Docker helps package your app with everything it needs so it runs the same on any computer.Imagine you want to share your NestJS app with a friend who does not have Node.js installed. Docker makes this easy by creating a container that includes Node.js and your app together.

🎯 Goal: Create a Dockerfile to containerize a basic NestJS application. You will start by setting up the base image, then add configuration for the app, copy the app files, install dependencies, build the app, and finally specify how to run it inside the container.

📋 What You'll Learn

Use the official Node.js 18 image as the base image

Set the working directory inside the container to /usr/src/app

Copy package.json and package-lock.json to the container

Run npm install to install dependencies

Copy the rest of the application files

Run npm run build to compile the NestJS app

Expose port 3000

Set the command to start the app with npm run start:prod

💡 Why This Matters

🌍 Real World

Docker containerization helps developers package their NestJS apps so they run consistently on any machine or cloud service without setup issues.

💼 Career

Knowing how to containerize backend applications with Docker is a valuable skill for backend developers, DevOps engineers, and cloud engineers.

1

Set the base image and working directory

Create a Dockerfile and write these two lines: use node:18 as the base image with FROM node:18, and set the working directory inside the container to /usr/src/app using WORKDIR /usr/src/app.

NestJS

FROM node:18
# Set working directory
WORKDIR /usr/src/app
# Your code here

Need a hint?

Use FROM to pick the base image and WORKDIR to set the folder inside the container.

2

Copy package files and install dependencies

Add these lines to your Dockerfile: copy package.json and package-lock.json to the container with COPY package*.json ./, then run npm install to install dependencies using RUN npm install.

NestJS

FROM node:18
WORKDIR /usr/src/app
# Copy package files
COPY package*.json ./
# Install dependencies
RUN npm install
# Your code here

Need a hint?

Use COPY to copy files and RUN to execute commands inside the container.

3

Copy app files and build the NestJS app

Add these lines to your Dockerfile: copy all other app files with COPY . ., then build the app using RUN npm run build.

NestJS

FROM node:18
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
# Copy app files
COPY . .
# Build the app
RUN npm run build
# Your code here

Need a hint?

Copy all files with COPY . . and build the app with npm run build.

4

Expose port and set the start command

Add these final lines to your Dockerfile: expose port 3000 with EXPOSE 3000, and set the command to start the app in production mode using CMD ["npm", "run", "start:prod"].

NestJS

FROM node:18
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build
# Expose port
EXPOSE 3000
# Start the app
CMD ["npm", "run", "start:prod"]
# Your code here

Need a hint?

Use EXPOSE to open the port and CMD to set the start command.