Proxy Another Domain to a VirtualHost: Easy Guide

To proxy requests from another domain to a virtual host, you can use a reverse proxy configuration. A reverse proxy acts as an intermediary for requests from clients seeking resources from servers. This can be useful in various scenarios, such as load balancing, security, and even exposing multiple services via a single domain.

Here’s a step-by-step guide on how to set up a reverse proxy using Apache HTTP Server (httpd) and Nginx, two popular web servers.

Using Apache HTTP Server

1. Install Apache:
   Ensure Apache is installed on your server. On most Linux distributions, you can install it using the package manager:

   sudo apt update
   sudo apt install apache2

2. Enable Necessary Modules:
   Enable the proxy and proxy_http modules if they are not already enabled.

   sudo a2enmod proxy
   sudo a2enmod proxy_http
   sudo systemctl restart apache2

3. Configure Virtual Host:
   Edit or create the virtual host configuration file. For example, create /etc/apache2/sites-available/yourdomain.conf:

   <VirtualHost *:80>
       ServerName yourdomain.com

       ProxyRequests Off
       ProxyPreserveHost On

       <Proxy *>
           Require all granted
       </Proxy>

       ProxyPass / http://virtualhost.example.com/
       ProxyPassReverse / http://virtualhost.example.com/

       ErrorLog ${APACHE_LOG_DIR}/yourdomain_error.log
       CustomLog ${APACHE_LOG_DIR}/yourdomain_access.log combined
   </VirtualHost>

4. Enable the Virtual Host:
   Enable the new site and reload Apache:

   sudo a2ensite yourdomain.conf
   sudo systemctl reload apache2

Using Nginx

1. Install Nginx:
   Ensure Nginx is installed on your server. On most Linux distributions, you can install it using the package manager:

   sudo apt update
   sudo apt install nginx

2. Configure Virtual Host:
   Edit or create the server block configuration file. For example, create /etc/nginx/sites-available/yourdomain:

   server {
       listen 80;
       server_name yourdomain.com;

       location / {
           proxy_pass http://virtualhost.example.com;
           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;
       }

       error_log /var/log/nginx/yourdomain_error.log;
       access_log /var/log/nginx/yourdomain_access.log;
   }

3. Enable the Server Block:
   Enable the new site by creating a symbolic link and reloading Nginx:

   sudo ln -s /etc/nginx/sites-available/yourdomain /etc/nginx/sites-enabled/
   sudo nginx -t
   sudo systemctl reload nginx

Explanation of Configuration

• ProxyRequests Off: Disables forward proxy requests, ensuring the server only acts as a reverse proxy.
• ProxyPreserveHost On: Ensures the Host header is passed to the backend server.
• ProxyPass / http://virtualhost.example.com/: Proxies all requests from yourdomain.com to virtualhost.example.com.
• ProxyPassReverse / http://virtualhost.example.com/: Ensures the response headers are correctly rewritten, so redirects and other headers from the backend server are handled properly.

Final Notes

• Ensure that the backend server (virtualhost.example.com) is properly configured to accept and respond to requests proxied through the reverse proxy.
• Make sure firewall rules and network configurations allow traffic between the proxy server and the backend server.
• Secure your reverse proxy setup by configuring SSL/TLS certificates using Let’s Encrypt or another certificate authority for secure HTTPS connections.
• Regularly monitor logs and performance to ensure the proxy is functioning correctly and efficiently.

By following these steps, you can successfully proxy requests from another domain to a virtual host using Apache or Nginx.