Scaling Out With Docker and Nginx

backend-Dockerfile

# Use a standard Node image from Docker Hub 
FROM node:boron

# The Dockerfile's author
LABEL Usama Ashraf

# Create a directory in the container where the code will be placed
RUN mkdir -p /backend-dir-inside-container

# Set this as the default, working directory.
# We'll land here when we SSH into the container.
WORKDIR /backend-dir-inside-container

# Copy everything inside src to our directory in the container
#ADD ./src /backend-dir-inside-container

# Our Nginx container will forward HTTP traffic to containers of 
# this image via port 3000.
EXPOSE 3000

docker-compose.yml

version: '3.2'
services:
  backend1:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  backend2:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  backend3:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  loadbalancer:
      build: ./load-balancer
      tty: true
      links:
          - backend1
          - backend2
          - backend3
      ports:
          - '8080:8080'

volumes:
  backend:

index.js

const express = require('express')
const app = express()

app.get('/', (req, res) =>  { 
    
    console.log('I just received a GET request on port 3000!')
    res.send('Hello World!');
})

app.listen(3000, () => console.log('I just connected on port 3000!'))

load-balancer-Dockerfile

# Use the standard Nginx image from Docker Hub
FROM nginx

# The Dockerfile's author
LABEL Usama Ashraf

# Copy custom configuration file from the current directory
COPY nginx.conf /etc/nginx/nginx.conf

EXPOSE 8080

# Start Nginx when the container has provisioned.
CMD ["nginx", "-g", "daemon off;"]

nginx.conf

events { worker_connections 1024; }

http {

 upstream localhost {
    server backend1:3000;
    server backend2:3000;
    server backend3:3000;
 }

 server {
    listen 8080;
    server_name localhost;

    location / {
       proxy_pass http://localhost;
       proxy_set_header Host $host;
    }
  }
}

package-lock.json

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