NodeJS "Hello World" Dockerised App

app.js

var express = require('express'); 
var app = express(); 
var PORT = 3000; 
  
app.get('/', (req, res) => { 
  res.send("Hello World") 
}) 
  
app.listen(PORT, function(err){ 
    if (err) console.log(err); 
    console.log("Server listening on PORT", PORT); 
});

Dockerfile

FROM node:12.16.3-alpine

COPY package.json package-lock*.json ./

RUN npm install

COPY . .

RUN npm run build

CMD ["npm", "run", "start"]