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vladyslav nykoliuk
vladyslav nykoliuk

Posted on • Updated on

Dockerizing a Node.js application [2022 revised]

For this tutorial, I will assume you are starting a brand new Node.js application. If you already have a Node.js application you want to Dockerize, head over to Step 3.

*Before starting this tutorial, please make sure you have Docker downloaded.

Step 1

Initialize a new node.js app with

npm init
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This will give you a package.json file that looks something like this

// package-lock.json
{
  "name": "sample_app",
  "version": "1.0.0",
  "description": "My First Dockerized Codebase",
  "author": "Your Name",
  "main": "app.js",
  "scripts": {
    "start": "node app.js"
  },
  "dependencies": {
    "express": "^4.17.1"
  }
}
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then run npm i (previously npm install) which will generate a package-lock.json.

Step 2

Next, we will create an app.js file

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

const PORT = [Your-port-here];

app.get('/', (req, res) => {
  res.send('Hello World');
});

app.listen(PORT, '0.0.0.0' () => {
  console.log('Server listening on Port ${PORT}');
});
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Step 3

Here comes the fun part...
First, create a Dockerfile

touch Dockerfile
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Inside the Dockerfile, you will need to define the following:

# you can find your node version with: node --version
FROM node:15

# Create app directory
WORKDIR /app

# Install app dependencies
COPY package*.json ./

# Install dependecies
RUN npm install

# Bundle app
COPY . .

# Define your port
EXPOSE 3000

# Tell Docker how to run your app
CMD [ "node", "app.js" ]

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Step 4

Additional files are needed for Docker to successfully build your app.

.dockerignore

node_modules/
# anything else you want for Docker to ignore
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docker-compose.yml

version: '3.7'   # you can find yours with python --version
services:    
    web:
        image: [your-image-name]
        build: .
        command: node app.js
        ports: 
            - "4040:4040"
        volumes: 
            - ./[your-image-name]/app
            - /app/node_modules
        depends_on:
            - mongodb
    mongodb:
        image: "mongo"
        ports:
            - "27017:27017"
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Step 5

Now that we have all the files, we can build and run the container.

Build a Docker container
docker build -t [your-app-name] .

Run the Docker container
docker run -it -p 3000:3000 [your-app-name]

Congratulations πŸ₯³
If you have made it this far, you have successfully Dockerized your Node.js app.

Addition Docker Commands

docker ps
Check for running containers

docker-compose run [app-name] npm run migrate
Run migration and create table

docker pull
Pulls an image or a repository from a registry

Top comments (2)

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olexandrpopov profile image
Oleksandr Popov

Recently somebody posted Docker Best Practices on dev.to. There are many usefull things.

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vladyslavnua profile image
vladyslav nykoliuk Author

Indeed it has lots of useful information. Thanks for the comment!

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