Basic Load Balancing for a Web System on DigitalOcean

#beginners #cloud #devops #tutorial

In this article we’ll build a simple and inexpensive load-balanced web setup on DigitalOcean.

The architecture is intentionally minimal:

1 DigitalOcean Load Balancer
2 small droplets
A lightweight web app running with Docker + PHP + Nginx

The goal is to show how quickly you can build a basic scalable web entry point without complex infrastructure.

Architecture diagram created with savnet.co:

Creating the first server

Go to your DigitalOcean account and create a small droplet.

Configuration used in this guide:

Image: Docker latest on Ubuntu 22.04
Region: choose the closest to your users
Authentication: SSH recommended (Password also works)
Hostname: WebServer-1

Once the droplet is ready, connect to the server.

Preparing the server

1. Create a user

adduser web_app
usermod -aG sudo web_app
sudo usermod -aG docker web_app
su - web_app

This user will run the application and manage Docker.

2. Create the application folder

mkdir -p ~/app
cd ~/app

3. Create the application files

`index.php`

A very small script that prints the server IP responding to the request.

<?php

echo 'Hi. From ip '.$_SERVER['SERVER_ADDR'];

`nginx.conf`

Basic Nginx configuration to serve PHP via PHP-FPM.

server {
    listen 80;
    server_name localhost;
    root /var/www/html;
    index index.php;

    location / {
        try_files $uri $uri/ =404;
    }

    location ~ \.php$ {
        fastcgi_pass 127.0.0.1:9000;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }
}

`docker-compose.yml`

This setup runs Nginx + PHP-FPM using Docker.

version: '3.8'

services:
  nginx:
    image: nginx:alpine
    container_name: nginx-web
    network_mode: host
    volumes:
      - ./:/var/www/html
      - ./nginx.conf:/etc/nginx/conf.d/default.conf
    depends_on:
      - php-fpm

  php-fpm:
    image: php:8.2-fpm
    container_name: php-app
    network_mode: host
    volumes:
      - ./:/var/www/html

4. Start the application

Run:

docker compose up

If everything is correct you should see the containers starting.

Open the server IP in your browser.

You should see something like:

Hi. From ip 10.x.x.x

Creating the Load Balancer

Now we create the DigitalOcean Load Balancer.

Configure:

HTTP forwarding
Attach WebServer-1

Once created, open the load balancer IP.

You’ll see something similar to this:

Notice that the response shows an internal server IP, because traffic between the load balancer and droplets happens inside DigitalOcean’s network.