Microservices with Node.js and Docker: A Complete Guide

Configuring the Environment with Docker

Docker is a platform that allows you to create, deploy and manage containers. Containers are isolated environments that contain everything that an application needs to function, ensuring that the software works consistently in any environment.

• For Windows and macOS: AccessDocker Desktopand download the appropriate installer for your operating system.
• Follow the installation instructions provided on the website.

• Linux: Follow the installation instructions specific to your Linux distribution available inofficial Docker documentation.
• Follow the installation instructions provided on the website.

• Creating a Container for Node.js: Let's create a basic environment for a Node.js service using Docker.

FROM node:14
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["node", "index.js"]

• Create the docker-compose.yml file:

version: '3.8'
services:
app:
build: .
ports:
  - "3000:3000"
                  

• File Structure:

/my-microservice
├── Dockerfile
├── docker-compose.yml
├── index.js
└── package.json
                  

• Commands to Build and Run:

docker-compose build
docker-compose up
                      

Communication between Microservices

For microservices to communicate, it is common to use HTTP/REST or messaging systems like RabbitMQ and Kafka. We will demonstrate the communication between two services using HTTP/REST.

• Example of HTTP Communication between Microservices:


• 1 - Service A (User Service):
• index.js

const express = require('express');
const app = express();
const port = 3001;

app.get('/user', (req, res) => {
  res.json({ name: 'John Doe', age: 30 });
});

app.listen(port, () => {
  console.log(User service running on port );
});
            

• 2 - Service B (Order Service):
• index.js

const express = require('express');
const axios = require('axios');
const app = express();
const port = 3002;

app.get('/order', async (req, res) => {
  try {
    const user = await axios.get('http://localhost:3001/user');
    res.json({ orderId: 123, user: user.data });
  } catch (error) {
    res.status(500).send(error.message);
  }
});

app.listen(port, () => {
  console.log( Order service running on port );
});

• Update docker-compose.yml:

version: '3.8'
services:
  user-service:
    build:
      context: ./user-service
    ports:
      - "3001:3001"
  order-service:
    build:
      context: ./order-service
    ports:
      - "3002:3002"

                  

• File Structure:

/microservices
  ├── docker-compose.yml
  ├── user-service
  │   ├── Dockerfile
  │   ├── index.js
  │   └── package.json
  └── order-service
      ├── Dockerfile
      ├── index.js
      └── package.json

• Commands to Build and Run:

docker-compose build
docker-compose up
                      

With this, the order service (order-service) can be communicate with the user service (user-service) through of an HTTP request.