Project: Packaging Node.js Services with Live Reloading

In this project, we will package a Node.js API server inside a Docker container. We will configure host bind mounts and package volumes so you can edit code on your host machine and see changes reflect in the container in real-time, without rebuilding the image.

1. Project Workflow

graph TD
    A[Create Node API Server] --> B[Write Dockerfile exposing port 3000]
    B --> C[Configure Bind Mount for src/ code]
    C --> D[Configure Anonymous Volume to protect node_modules]

2. Walkthrough Guide

Step 1: Create a Basic Node.js API

Create a new directory and initialize the Node project:

mkdir node-docker-dev
cd node-docker-dev
npm init -y
npm install express
npm install --save-dev nodemon

Add a start script to your package.json file:

"scripts": {
  "dev": "nodemon index.js"
}

Create an index.js file:

// index.js
const express = require('express');
const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.send('Hello from inside the Docker container!');
});

app.listen(port, () => {
  console.log(`API listening on port ${port}`);
});

Step 2: Write the Dockerfile

Create a Dockerfile in your root directory:

FROM node:20-alpine
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "run", "dev"]

Create a .dockerignore file to prevent copying local node modules:

node_modules
npm-debug.log

Step 3: Run the Container with Live Reloading

Run the container, configuring a bind mount for your source code and an anonymous volume to protect the container's node_modules folder from being overwritten by your empty local directory:

docker run -d \
  -p 3000:3000 \
  --name api-dev-container \
  -v $(pwd):/app \
  -v /app/node_modules \
  my-node-api-image

Open index.js on your host machine, change the response text, and save the file. The server inside the container will reload automatically. Note: On Windows PowerShell, use $(pwd) to get the current working directory.