Docker Nginx Central Gateway

A production-ready Central Gateway boilerplate using Nginx and Docker Compose. It handles:

• Reverse Proxy: Routing traffic to different Dockerized applications on the same host.
• SSL Termination: Automatic HTTPS with Let's Encrypt (Certbot).
• Zero Downtime: Reload configurations without stopping services.

Architecture

This setup uses an external Docker network named proxy-net.

• Gateway (Nginx): Runs on proxy-net and handles ports 80/443.
• Your Apps: Run on proxy-net (internal only) and are reachable by Nginx via container names.

Prerequisites

1. Install Docker & Docker Compose.
2. Create the shared network (required once per host):

   docker network create proxy-net

Directory Structure

gateway/
├── docker-compose.yml
├── nginx/
│   └── conf.d/
│       ├── default.conf         # Health check & fallback
│       └── app.conf.example     # Template for your apps
├── tests/
│   └── verify_setup.py          # Infrastructure verification
└── LICENSE

Quick Start

1. Clone and Start:

   git clone <your-repo-url> gateway
   cd gateway
   docker compose up -d

2. Verify: Visit http://localhost (or your server IP). You should see "Gateway is running!".

Adding a New App (Step-by-Step)

1. Prepare Nginx Config: Copy the example and edit it:

   cp nginx/conf.d/app.conf.example nginx/conf.d/my-app.conf

   Edit my-app.conf: Change app.example.com to your actual domain and update the proxy_pass upstream.

2. Get SSL Certificate:

   docker compose run --rm certbot certonly --webroot --webroot-path=/var/www/certbot -d yourdomain.com

3. Reload Nginx:

   docker compose exec nginx nginx -s reload

Migration Guide

How to move an existing standalone app to this gateway architecture.

Before (Standalone App): The app handles its own ports and SSL.

services:
  web:
    image: your-username/my-web-app:latest
    ports:
      - "80:80" # ❌ Remove this
      - "443:443" # ❌ Remove this

After (Gateway-Ready): Connect to proxy-net and remove port bindings.

services:
  web:
    image: your-username/my-web-app:latest
    restart: unless-stopped
    environment:
      - PORT=3000
    networks:
      - proxy-net  # ✅ Connect to gateway
    # ports: ... (Removed)

networks:
  proxy-net:
    external: true

Testing

Run the verification script to check your folder structure:

python3 tests/verify_setup.py