How to Setup Apache Reverse Proxy

How to use Apache as a reverse proxy server

Apache needs a few special tools, called modules, turned on before it can work as a reverse proxy server.

Here’s how to enable these Apache modules:

sudo a2enmod proxy
sudo a2enmod proxy_http
sudo a2enmod proxy_ajp
sudo a2enmod rewrite
sudo a2enmod deflate
sudo a2enmod headers
sudo a2enmod proxy_balancer
sudo a2enmod proxy_connect
sudo a2enmod proxy_html

The basic configuration for Apache to serve as a proxy server can be done using the line code below. You configure a VirtualHost for the domain and specify a location to the backend server for Apache to send requests it receives.

<VirtualHost *:*>
    ServerName example.com
    ProxyPreserveHost On

    # Servers to proxy the connection, or;

    ProxyPass / http://127.0.0.1:8080/
    ProxyPassReverse / http://127.0.0.1:8080/

</VirtualHost>

This configuration tells Apache to send all requests for your example.com domain’s root directory (/) to the server at http://127.0.0.1:8080.

For example, if a client requests http://example.com/, Apache will forward the request to the backend server defined on the ProxyPass and ProxyPassReverse lines: http://127.0.0.1:8080.

While this setup covers the basics, Apache offers many advanced configurations for proxy servers. This simple example should give you a clear picture of how they function.

Apache can also handle requests for non-HTTP servers, such as:

• proxy_fcgi – reverse proxy to a FastCGI server.
• proxy_uwsgi – reverse proxy to a uwsgi server.
• proxy_scgi – reverse proxy to an SCGI server.

A common Apache reverse proxy to non-HTTP hosts is done using PHP-FPM. An example is how Apache serves PHP scripts.

<VirtualHost *:*>
    ServerName example.com
    ProxyPreserveHost On

    # Servers to proxy the connection, or;

    <FilesMatch .php$>
        # 2.4.10+ can proxy to unix socket
         SetHandler "proxy:unix:/run/php/php7.4-fpm.sock|fcgi://localhost"
    </FilesMatch>

</VirtualHost>

You will need to enable a few modules for apache2 to work with PHP-FPM:

sudo a2enmod actions fcgid alias proxy_fcgi

How to configure Apache reverse proxy options

Setting up your Apache reverse proxy involves choosing options that tell it how to handle incoming requests and send them to your other servers.

<VirtualHost *:*>
    ServerName example.com

    UseCanonicalName on
    ProxyPreserveHost on
    CacheStaleOnError on
    RemoteIPHeader X-Forwarded-For
    ProxyRequests Off

    ProxyPass / http://127.0.0.1:8080/
    ProxyPassReverse / http://127.0.0.1:8080/

</VirtualHost>

You can visit the site for more options to use in your environment.

That should do it!

Conclusion:

• Setting up Apache as a reverse proxy allows you to efficiently manage client requests and backend servers.
• Apache provides extensive modules that enhance its functionality for reverse proxy operations.
• Simple configurations can effectively route requests to desired backend applications, such as Node.js, Python, and PHP-FPM.
• Advanced configurations are available for handling various types of requests beyond HTTP.
• Understanding the fundamental reverse proxy concepts can help optimize web application performance and reliability.
• For further customization and options, refer to the official Apache documentation on reverse proxy settings.