Achieving High Availability Deployment of PHP Applications Using Docker Compose and Nginx

Implementing High Availability Deployment for PHP Applications with Docker Compose and Nginx

High availability is a critical requirement in modern web application development. With Docker Compose and Nginx, you can easily achieve a high availability deployment for PHP applications, ensuring your application remains stable and accessible even when failures occur.

Docker is a leading containerization platform that packages applications and their dependencies into isolated containers. Docker Compose simplifies defining and managing multi-container applications.

Nginx is not only a high-performance web server but also a widely used reverse proxy server. It distributes incoming traffic to multiple backend servers, providing load balancing to enhance system availability and performance.

Defining Docker Compose Services

First, create a docker-compose.yml file to define multiple application instances and an Nginx container. Example configuration is as follows:

version: '3'
services:
  app1:
    build:
      context: .
      dockerfile: Dockerfile
    restart: always
  app2:
    build:
      context: .
      dockerfile: Dockerfile
    restart: always
  nginx:
    image: nginx
    ports:
      - "80:80"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
    restart: always

In this configuration, app1 and app2 are two PHP application containers, which can run identical or different versions of the app to achieve redundancy. The Nginx container receives traffic and performs load balancing.

Nginx Load Balancing Configuration

Create and mount an nginx.conf configuration file to the Nginx container with the following example content:

http {
  upstream backend {
    server app1:8080;
    server app2:8080;
  }

  server {
    listen 80;

    location / {
      proxy_pass http://backend;
      proxy_set_header Host $host;
      proxy_set_header X-Real-IP $remote_addr;
    }
  }
}

This configuration defines an upstream named backend with two application server addresses. Nginx distributes incoming requests to these two PHP app containers for load balancing.

Building the PHP Application Container Image

Write a Dockerfile customized to your application needs. Example content:

FROM php:7.4.15-fpm

WORKDIR /var/www/html

COPY . .

RUN chmod -R 755 storage

CMD ["php-fpm"]

This Dockerfile uses the official PHP image, sets the working directory, copies application code, configures directory permissions, and starts the PHP-FPM server.

Starting the High Availability PHP Application

After completing configurations, use the following command to start all containers:

docker-compose up -d

This command launches all defined containers in detached mode, allowing your PHP application to run behind Nginx’s load balancing and achieve high availability.

Summary

By leveraging Docker Compose and Nginx, you can build a high availability deployment environment for PHP applications. Multi-container architecture and load balancing ensure continuous availability in case of single points of failure and support horizontal scaling.

The article provides a basic example. You can further customize configurations to suit complex production environments.