How to Setup Apache Reverse Proxy

An Apache reverse proxy is a helpful middleman server that takes web traffic from visitors and sends it to the right place on your backend servers. Running version 2.4 or newer gives you access to built-in modules that handle this traffic routing smoothly.

This setup lets Apache protect your web apps and share visitor traffic across multiple servers so your site stays fast and reliable. It works well for programs like Node.js or Python that do not have their own built-in web servers.

How to use Apache as a reverse proxy server

Apache relies on specialized components called modules to function as a reverse proxy. Administrators must enable the mod_proxy and mod_proxy_http modules. These components help Apache manage website traffic by sending visitor requests to another server and retrieving responses.

Here is how to enable these Apache modules:

The ProxyPass directive in the Apache web server configuration identifies the backend server that will receive incoming website requests. This configuration line makes the Apache proxy server act as a middleman, forwarding traffic to the correct server. Apache version 2.4.54 commonly uses this directive.

<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 the 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 forwards that request to the backend server defined on the ProxyPass and ProxyPassReverse lines: http://127.0.0.1:8080.

Apache offers advanced settings for proxy servers beyond this basic configuration. This example illustrates how Apache proxy servers function.

Apache also handles 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.

Apache often proxies requests to non-HTTP hosts using PHP-FPM. This method represents the standard way 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>

Enabling a few modules allows apache2 to work with PHP-FPM:

Configuring an Apache reverse proxy involves setting up options that dictate how the server handles incoming requests and forwards them. This setup ensures Apache knows precisely where to send traffic and preserves critical details, such as the original website address.

<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>

Consult the site for more options to use in your environment.

That completes the setup process.

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.