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Set up subdomain routing NGINX

Dynamic Subdomain Routing for *.qool.ovh (Nginx)

0. Introduction

Goal

Automatically route requests for <subdomain>.qool.ovh to the corresponding directory /var/www/qool/<subdomain>, without creating a new DNS record or Nginx config for each site.

Use case

  • test.qool.ovh → /var/www/qool/test
  • blog.qool.ovh → /var/www/qool/blog
  • demo.qool.ovh → /var/www/qool/demo

1. DNS Configuration (Wildcard)

Create wildcard DNS record

At your DNS provider (OVH), create the following record:

Type: A
Name: *.qool.ovh
Value: <SERVER_IP>
TTL: Auto

This ensures that all subdomains of qool.ovh resolve to your server.

2. Directory Structure

Base webroot layout

/var/www/qool/
 ├─ test/
 │   └─ index.php
 ├─ blog/
 │   └─ index.php
 └─ demo/
     └─ index.php

Ownership and permissions

sudo chown -R max:www-data /var/www/qool
find /var/www/qool -type d -exec chmod 750 {} \;
find /var/www/qool -type f -exec chmod 640 {} \;

3. Nginx Wildcard Configuration

Create Nginx site file

sudo nano /etc/nginx/sites-available/qool.ovh

Wildcard server block

server {
    listen 80;

    # Capture subdomain name dynamically
    server_name ~^(?<site>[a-z0-9-]+)\.qool\.ovh$;

    root /var/www/qool/$site;
    index index.php index.html;

    # Reject non-existing site directories
    if (!-d /var/www/qool/$site) {
        return 404;
    }

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php8.3-fpm.sock;
    }
}

Enable the site

sudo ln -s /etc/nginx/sites-available/qool.ovh /etc/nginx/sites-enabled/
sudo nginx -t
sudo systemctl reload nginx

4. How the Routing Works

Nginx logic

  • Nginx matches <subdomain>.qool.ovh using a regex
  • The subdomain is captured into variable $site
  • The document root is set to /var/www/qool/$site
  • If the directory does not exist, a 404 is returned

Example

Request:

GET http://test.qool.ovh

Results in:

root = /var/www/qool/test

5. Testing

Create a test file

nano /var/www/qool/test/index.php

<?php
echo "Site: test.qool.ovh";

Test locally

curl -H "Host: test.qool.ovh" http://localhost

Test in browser

Open:

http://test.qool.ovh

6. Notes & Best Practices

  • No per-site Nginx configuration required
  • Adding a new site = create a directory only
  • Works with PHP, static files, and frameworks
  • Compatible with wildcard TLS certificates
  • Production-safe when directory existence is validated

Final Summary

  • Wildcard DNS resolves all subdomains
  • Nginx regex captures subdomain name
  • Filesystem routing maps subdomain → directory
  • Scales to unlimited sites with zero config changes
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