Setting up a reverse proxy with Nginx and Docker-Compose is an essential skill for DevOps and developers. A reverse proxy enhances application performance, security, and scalability by managing tasks like SSL termination, caching, and request routing—all while isolating your application.

Setting Up a Reverse Proxy with Nginx and Docker-Compose

Introduction

Reverse proxies like Nginx enable you to manage critical web application functionalities such as SSL encryption, caching, and service isolation. By handling these tasks outside of your application, Nginx ensures a secure and streamlined setup. Pairing this with Docker-Compose provides an easy way to manage containers and streamline deployment workflows.

In this guide, we’ll explore setting up Nginx as a reverse proxy, configuring Docker-Compose for multiple services, enabling caching, and securing HTTP traffic with SSL.

Section 1: What is Docker-Compose?

Docker-Compose simplifies the management of multi-container applications. It allows you to define services, networks, and volumes in a single docker-compose.yml file.

Here’s an example configuration:

version: '3'
services:
  nginx: 
    image: nginx:latest
    container_name: reverse_proxy
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
    ports:
      - 80:80
      - 443:443

  web_app:
    image: your_app_image:latest
    container_name: web_app
    expose:
      - "80"

Key Features:

• Networks: Connect containers securely.
• Volumes: Persist data across container restarts.
• Environment Variables: Simplify configurations for different environments.

Section 2: Configuring Nginx as a Reverse Proxy

Nginx acts as the central hub, routing incoming requests to appropriate backend services. Here’s a sample Nginx configuration:

http {
  server {
    server_name example.com;

    location /app1 {
      proxy_pass http://web_app:80;
      rewrite ^/app1(.*)$ $1 break;
    }

    location /app2 {
      proxy_pass http://another_service:5000;
      rewrite ^/app2(.*)$ $1 break;
    }
  }
}

Explanation:

• proxy_pass: Routes requests to backend services.
• rewrite: Adjusts the request path for the target service.

Section 3: Enabling Caching in Nginx

Caching can significantly improve performance by storing responses for reuse. Add caching to your Nginx configuration as follows:

http {
  proxy_cache_path /data/nginx/cache keys_zone=cache_zone:10m max_size=1g;

  server {
    proxy_cache cache_zone;
    proxy_cache_valid 200 1d;

    location / {
      proxy_pass http://web_app:80;
    }
  }
}

Section 4: Securing HTTP Traffic with SSL

SSL encrypts traffic between clients and your reverse proxy. Use Certbot to generate free certificates from Let’s Encrypt.

Steps to Generate and Configure SSL Certificates:

1. Install Certbot:

   sudo apt install certbot
   

2. Generate Certificates:

   certbot --standalone -d example.com
   

3. Update Nginx Configuration:

   server {
     listen 443 ssl;
     ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
     ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
   
     location / {
       proxy_pass http://web_app:80;
     }
   }
   

4. Automate Certificate Renewal:
   Add the following Cron job to automate renewals:

   @daily certbot renew --pre-hook "docker-compose down" --post-hook "docker-compose up -d"
   

Section 5: Bringing It All Together

Below is the final docker-compose.yml and nginx.conf setup:

docker-compose.yml:

version: '3'
services:
  nginx:
    image: nginx:latest
    container_name: reverse_proxy
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
      - /etc/letsencrypt/:/etc/letsencrypt/
    ports:
      - 80:80
      - 443:443

  web_app:
    image: your_app_image:latest
    container_name: web_app
    expose:
      - "80"

nginx.conf:

http {
  server {
    listen 80;
    listen 443 ssl;
    server_name example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    location / {
      proxy_pass http://web_app:80;
    }
  }
}

Conclusion

With Nginx and Docker-Compose, you can create a powerful reverse proxy setup that includes SSL encryption, caching, and seamless traffic management. While this guide provides a foundational setup, it’s recommended to fine-tune configurations for production environments.

By implementing these steps, you’ll enhance the security, scalability, and reliability of your applications.