# nginx Configuration

This service should usually sit behind nginx. Let nginx handle TLS, public ports, compression, and connection buffering. Let the Go app listen on loopback.

## App Environment

Run the app with:

```bash
ADDR=127.0.0.1:8080
TRUST_PROXY_HEADERS=true
TRUSTED_PROXY_CIDRS=127.0.0.1/32,::1/128
LOG_FORMAT=json
```

If nginx runs in Docker or on another private host, add that proxy network to `TRUSTED_PROXY_CIDRS`, for example:

```bash
TRUSTED_PROXY_CIDRS=127.0.0.1/32,::1/128,172.16.0.0/12
```

## Basic Reverse Proxy

Replace `ip.example.com` with your domain.

```nginx
upstream ipecho {
    server 127.0.0.1:8080;
    keepalive 16;
}

server {
    listen 80;
    server_name ip.example.com;

    location / {
        proxy_pass http://ipecho;
        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;
        proxy_set_header X-Forwarded-Host $host;

        proxy_connect_timeout 5s;
        proxy_send_timeout 15s;
        proxy_read_timeout 15s;
    }
}
```

## HTTPS Server Block

After installing a certificate, use:

```nginx
upstream ipecho {
    server 127.0.0.1:8080;
    keepalive 16;
}

server {
    listen 80;
    server_name ip.example.com;
    return 301 https://$host$request_uri;
}

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

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

    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

    location / {
        proxy_pass http://ipecho;
        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 https;
        proxy_set_header X-Forwarded-Host $host;

        proxy_connect_timeout 5s;
        proxy_send_timeout 15s;
        proxy_read_timeout 15s;
    }
}
```

## With A CDN Or Load Balancer In Front

If nginx is behind another proxy, configure nginx real IP handling first so `$remote_addr` becomes the actual client address before it is passed to the Go app.

Example shape:

```nginx
real_ip_header X-Forwarded-For;
real_ip_recursive on;

# Add only the CIDR ranges for proxies you control or your CDN publishes.
set_real_ip_from 203.0.113.0/24;
set_real_ip_from 2001:db8::/32;
```

Keep those CIDR ranges current. Do not trust `0.0.0.0/0` or `::/0`.

## Verify

```bash
curl https://ip.example.com/ip
curl https://ip.example.com/json
curl -I https://ip.example.com/favicon.ico
curl http://127.0.0.1:8080/healthz
```

Expected:

- `/ip` returns the client IP as plain text.
- `/json` shows `ip`, `remote_addr`, headers, method, and path.
- `/favicon.ico` returns `Content-Type: image/x-icon`.
- `/healthz` returns `ok`.