reverse-proxy

The saved excerpt is a snapshot from review. The external source remains the complete and most current version.

---
name: reverse-proxy
description: Configure nginx and Traefik as reverse proxies. Implement SSL termination and routing. Use when setting up application gateways.
license: MIT
metadata:
  author: devops-skills
  version: "1.0"
---

# Reverse Proxy

Configure reverse proxies to route traffic, terminate TLS, enforce rate limits, and serve as the gateway between clients and backend services.

## When to Use

- Routing traffic from a public domain to one or more backend services.
- Terminating TLS at the edge and forwarding plain HTTP to backends.
- Adding rate limiting, CORS, security headers, and access control.
- Consolidating multiple services under a single domain with path-based routing.
- Handling WebSocket upgrades, gRPC proxying, or HTTP/2 passthrough.

## Prerequisites

- Backend service(s) running on known host:port.
- TLS certificate (Let's Encrypt, ACM, or self-signed for development).
- nginx 1.25+ or Traefik 3.x installed.
- DNS record pointing the domain to the proxy server.

## nginx Reverse Proxy

### Basic HTTPS Proxy with Redirect

```nginx
# /etc/nginx/sites-available/app.example.com
server {
    listen 80;
    server_name app.example.com;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    server_name app.example.com;

    # TLS configuration
    ssl_certificate     /etc/letsencrypt/live/app.example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/app.example.com/privkey.pem;
    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_ciphers         ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384;
    ssl_prefer_server_ciphers on;
    ssl_session_cache   shared:SSL:10m;
    ssl_session_timeout 10m;

    # Security headers
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;
    add_header X-Frame-Options DENY always;
    add_header X-Content-Type-Options nosniff always;
    add_header Referrer-Policy strict-origin-when-cross-origin always;

    # Proxy to backend
    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        # Timeouts
        proxy_connect_timeout 5s;
        proxy_read_timeout 60s;
        proxy_send_timeout 60s;

        # Buffering
        proxy_buffering on;
        proxy_buffer_size 4k;
        proxy_buffers 8 4k;
    }
}
```

### Path-Based Routing to Multiple Services

```nginx
server {
    listen 443 ssl http2;
    server_name app.example.com;

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

    # Frontend SPA
    location / {
        proxy_pass http://127.0.0.1:3000;
        proxy_set_header Host $host;
    }

    # API backend
    location /api/ {
        proxy_pass http://127.0.0.1:8080/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_read_timeout 120s;
    }

    # WebSocket endpoint
    location /ws/ {
        proxy_pass http://127.0.0.1:8080;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
        proxy_read_timeout 86400s;  # 24h for long-lived connections
    }

    # Static assets with caching
    location /static/ {
        alias /var/www/static/;
        expires 30d;
        add_header Cache-Control "public, immutable";
    }
}
```

### Rate Limiting

```nginx
# Define rate limit zones in http block
http {
    # 10 requests/second per IP
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;

    # 1 request/second for login
    limit_req_zone $binary_remote_addr zone=login_limit:10m rate=1r/s;

    # Connection limit per IP