Tạo một package.json Package.json

{
  "name": "product",
  "version": "1.0.0",
  "description": "Product API microservice",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Cuong",
  "license": "MIT",
  "dependencies": {
    "express": "^4.16.2",
    "nodemon": "^1.12.1"
  }
}

và một file index.js
```JavaScript
const express = require('express')
const app = express()

app.get('/', (req, res) => res.send('Quái vật lộn xộn'))

app.listen(3000, () => console.log('Example app listening on port 3000!'))

Dockerfile

FROM node:alpine RUN mkdir -p /usr/microservice WORKDIR /usr/microservice COPY yarn.lock /usr/microservice RUN yarn install COPY ./ /usr/microservice CMD node index.js EXPOSE 3000

docker build -t productservice .

docker run -d --name proservice -p 3000:3000 productservice

docker run -it -d --name proservice -p 3000:3000 productservice /bin/ash

----------
Để hot reload chúng ta dùng nodemon
chạy lệnh npx nodemon
Docker file như sau

FROM node:alpine RUN mkdir -p /usr/microservice WORKDIR /usr/microservice COPY yarn.lock /usr/microservice RUN yarn install COPY ./ /usr/microservice CMD npx nodemon EXPOSE 3000 ```