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D4 S2 Service Discovery with Consul, Node.js (using Axios), and Nginx Automated in Docker Compose

Watch recorded video: https://youtu.be/Cna9I2ZvQvA

Prerequisites

  • Basic knowledge of Docker and Docker Compose.
  • Node.js and Nginx basics.
  • Docker and Docker Compose installed on your machine.

1. Setting Up Consul

Create a directory named consul-nginx-node:

mkdir consul-nginx-node
cd consul-nginx-node

Inside this directory, create a docker-compose.yml file:

version: '3'

services:
  consul:
    image: consul:latest
    container_name: consul
    ports:
      - "8500:8500"
      - "8600:8600/udp"
    command: "agent -dev -client=0.0.0.0"
    networks:
      - consul-network

networks:
  consul-network:
    driver: bridge

2. Node.js Service

Let's create a simple Node.js service that will register itself with Consul using Axios.

  1. Create a Node.js Server

In the consul-nginx-node directory, create a folder called node-app and navigate into it:

mkdir node-app
cd node-app

Create a server.js file with the following content:

const express = require('express');
const axios = require('axios');
const os = require('os');

const app = express();
const PORT = process.env.PORT || 3000;
const CONSUL_HOST = process.env.CONSUL_HOST || 'consul';
const SERVICE_NAME = 'node-service';

app.get('/', (req, res) => {
  res.send(`Hello from ${SERVICE_NAME} running on ${os.hostname()}`);
});

app.listen(PORT, async () => {
  console.log(`${SERVICE_NAME} is running on port ${PORT}`);

  // Register service with Consul using Axios
  try {
    const response = await axios.put(`http://${CONSUL_HOST}:8500/v1/agent/service/register`, {
      Name: SERVICE_NAME,
      ID: SERVICE_NAME,
      Address: os.hostname(),
      Port: PORT,
      Check: {
        HTTP: `http://${os.hostname()}:${PORT}/`,
        Interval: '10s'
      }
    });
    console.log('Service registered with Consul:', response.data);
  } catch (error) {
    console.error('Error registering service:', error.message);
  }
});
  1. Dockerize the Node.js Application

In the node-app directory, create a Dockerfile:

FROM node:14

WORKDIR /app

COPY package*.json ./
RUN npm install

COPY . .

CMD ["node", "server.js"]

Also, create a package.json file:

{
  "name": "node-service",
  "version": "1.0.0",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "axios": "^0.21.1",
    "express": "^4.17.1"
  }
}

3. Nginx as a Reverse Proxy

Nginx will serve as a reverse proxy to distribute traffic between multiple instances of the Node.js service registered with Consul.

  1. Nginx Configuration

Back in the consul-nginx-node directory, create a nginx folder and an nginx.conf file inside it:

mkdir nginx
cd nginx
events {
    worker_connections 1024;
}

http {
    upstream node-service {
        server node-service:3000;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://node-service;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
    }
}
  1. Dockerize Nginx

Create a Dockerfile inside the nginx directory:

FROM nginx:alpine
COPY nginx.conf /etc/nginx/nginx.conf

4. Docker Compose Configuration

Finally, we need to link everything together using Docker Compose.

Update the docker-compose.yml file:

version: '3'

services:
  consul:
    image: consul:latest
    container_name: consul
    ports:
      - "8500:8500"
      - "8600:8600/udp"
    command: "agent -dev -client=0.0.0.0"
    networks:
      - consul-network

  node-service:
    build: ./node-app
    container_name: node-service
    ports:
      - "3000"
    environment:
      - CONSUL_HOST=consul
      - PORT=3000
    networks:
      - consul-network
    depends_on:
      - consul

  nginx:
    build: ./nginx
    container_name: nginx
    ports:
      - "80:80"
    networks:
      - consul-network
    depends_on:
      - node-service

networks:
  consul-network:
    driver: bridge

5. Running the Setup

Now, let's bring everything up:

docker-compose up --build
  • The Consul server will start and be accessible at http://localhost:8500.
  • The Node.js service will start and register itself with Consul using Axios.
  • Nginx will proxy requests to the Node.js service.

6. Testing the Setup

Open your browser and go to http://localhost. You should see the message "Hello from node-service running on [container_id]". The Node.js service is now being proxied through Nginx, and it's discoverable by Consul.