Server modules

You can extend Project Karpacz with modules written in Rust.

The following modules are built into Project Karpacz:

• cache (from Project Karpacz 0.4.0) - this module enables server response caching.
• cgi (from Project Karpacz 0.5.0) - this modules enables the execution of CGI programs.
• fproxy (from Project Karpacz 0.3.0) - this module enables forward proxy functionality.
• rproxy (from Project Karpacz 0.2.0) - this module enables reverse proxy functionality, if either proxyTo or secureProxyTo configuration property is specified.

The following modules are dynamically linked (not supported on musl libc builds), and available in both source and binary form:

• example - this module responds with "Hello World!" for "/hello" request paths.

Module notes

cache module

The cache module is a simple in-memory cache module for Project Karpacz that works with "Cache-Control" and "Vary" headers. The cache is shared across all threads.

If you use this module with Project Karpacz's static file serving functionality, set the caching headers for the cache to work, and add "ETag" and "Accept-Encoding" to either a list of headers in the Vary header or in the cacheVaryHeaders property in the Project Karpacz configuration.

cgi module

To run PHP scripts with this module, you may need to adjust the PHP configuration file, typically located at /etc/php/<php version>/cgi/php.ini, by setting the cgi.force_redirect property to 0. If you don't make this change, PHP-CGI will show a warning indicating that the PHP-CGI binary was compiled with force-cgi-redirect enabled. It is advisable to use directories outside of cgi-bin for user uploads and downloads to prevent the cgi module from mistakenly treating uploaded scripts with shebangs and ELF binary files as CGI applications, which could lead to issues such as malware infections, remote code execution vulnerabilities, or 500 Internal Server Errors.

fproxy module

If you are using the fproxy module, then hosts on the local network and local host are also accessible from the proxy. You may block these using a firewall, if you don’t want these hosts to be accessible from the proxy.