How to Fix WordPress "Too Many Redirects" in Docker behind Reverse Proxy

#docker #wordpress #nginx #devops

📖 Original Reference: Originally published with full architecture diagrams and server configuration templates at alexmaina.dev/wordpress-docker-redirect-loop.

Running WordPress inside Docker behind a reverse proxy (like Nginx Proxy Manager, Traefik, Caddy, or Cloudflare) often leads to the dreaded browser error:

ERR_TOO_MANY_REDIRECTS

The browser gets trapped in an infinite HTTP 301 loop. Here is why this happens and how to permanently fix it in under 60 seconds.

⚡ The 30-Second Solution

Open your WordPress volume mount and edit wp-config.php. Paste this snippet BEFORE the line /* That's all, stop editing! Happy publishing. */:

// Trust HTTPS termination from your Reverse Proxy
if (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') !== false) {
    $_SERVER['HTTPS'] = 'on';
}

define('WP_HOME', 'https://yourdomain.com');
define('WP_SITEURL', 'https://yourdomain.com');
define('FORCE_SSL_ADMIN', true);

1. Anatomy of the Loop: Why Does it Happen?

In a modern containerized stack:

The user requests https://yourdomain.com (encrypted on port 443).
The Reverse Proxy terminates the SSL session (decrypts the traffic) and forwards the request internally to the WordPress container via HTTP on port 80.
Inside the container, PHP checks $_SERVER['HTTPS']. Because internal Docker network communication is unencrypted, $_SERVER['HTTPS'] is empty or off.
WordPress sees that its configured site URL is HTTPS, thinks the visitor accessed via insecure HTTP, and responds with an HTTP 301 Moved Permanently directing back to https://yourdomain.com.
The browser follows the redirect, the proxy intercepts it again on port 443, forwards it via port 80, and the cycle repeats infinitely until the browser throws ERR_TOO_MANY_REDIRECTS.

2. Nginx Reverse Proxy Headers

Ensure your upstream Nginx proxy passes the correct forwarded protocol headers:

server {
    listen 443 ssl http2;
    server_name yourdomain.com;

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

If using Nginx Proxy Manager (NPM):

Under Details: Scheme is http, Forward Host is the container name, Port is 80.
Under SSL: Enable Force SSL and HTTP/2 Support.

3. The Cloudflare Trap: Flexible vs Full (Strict)

If your DNS is proxied through Cloudflare (orange cloud active):

Never use Flexible SSL: Flexible instructs Cloudflare to contact your origin server strictly on port 80 (HTTP). If WordPress enforces HTTPS, Cloudflare and your origin will bounce redirects back and forth indefinitely.
Fix: Change your Cloudflare SSL/TLS encryption mode to Full or Full (Strict).

4. Verification with cURL

Run this terminal command to test the raw HTTP status without browser cache pollution:

curl -ILs -o /dev/null -w "%{http_code} -> %{url_effective}\n" https://yourdomain.com

Expected output:

200 -> https://yourdomain.com/

If you see 20 consecutive 301 -> ... lines, the PHP block was either placed too late in wp-config.php or the reverse proxy is stripping the X-Forwarded-Proto header.

Author: Alessandro Mainardi — Software Developer & Computer Engineering Student @ UniBo. Explore more self-hosting & Docker guides at alexmaina.dev.

DEV Community