The CGI (Common Gateway Interface) allows to interact with a third party program that process a HTTP request and generate content on the fly. This is the old-fashion mechanism to run programs through a HTTP server.
When a program runs using the CGI interface, the server will spawn a new process to make the script run on new environment, this is a known major performance issue of CGI.
Note: If your server requires to achieve high performance, is suggested to use the FastCGI interface instead of the old-fashion CGI.
To enable the CGI plugin, please follow the steps mentioned on Plugins section. The plugin name is monkey-cgi.so, so make sure the plugin entry is Load and the absolute path is correct.
Once the plugin is loaded, you need to define if the CGI plugin will run for the whole server as a global feature or if it will be just for a specific sets of Virtual Hosts.
The CGI plugin configuration can be placed on two locations basically depending of the need, if it will be applied to the whole context of the server, the configuration must go into the conf/plugins/cgi/cgi.conf configuration file. In the other hand if it will be applied to a specific Virtual Hosts, it should be placed on each Virtual Hosts configuration file.
The following schema must be applied to the target configuration file, the main section name is [CGI] and it support multiple entries named matches that act like rules to decide whatever the incoming request should be processed by the CGI plugin or not. The schema looks as follows:
[CGI]
Match /cgi-bin/.*\.cgi
Match /.*\.php /usr/bin/php-cgi application/x-httpd-php
In the above example we can see two rules for matching CGI programs that needs to be handled. A Match rule can be simple or extended:
| rule type | format |
|---|---|
| simple | Match REGEX |
| extended | Match REGEX [INTERPRETER] [MIMETYPE] |
The REGEX represents a Regular expression to match the target file that is being requested, make sure it also aligns to the URL. On simple mode the target file is executed directly, on the other hand the extended version of the format allows to specify an Interpreter program that will be used to process the target file, a common example for this cases is a file made in Perl, Python, Lua or any scripting-like language. The last argument is an optional MIME Type to be used when sending back the response, if your script do not handle this, make sure to set this field with a proper value.
If for some reason when using the extended format mode the Interpreter cannot be found or executed by Monkey, it will trigger a 500 Internal Server Error response to the client.