Rsyslog has a modular design. This enables functionality to be dynamically loaded from modules, which may also be written by any third party. Rsyslog itself offers all non-core functionality as modules. Consequently, there is a growing number of modules. Here is the entry point to their documentation and what they do (list is currently not complete)
Please note that each module provides (case-insensitive) configuration parameters, which are NOT necessarily being listed below. Also remember, that a modules configuration parameter (and functionality) is only available if it has been loaded.
It is relatively easy to write a rsyslog module. If none of the provided modules solve your need, you may consider writing one or have one written for you by Adiscon’s professional services for rsyslog (this often is a very cost-effective and efficient way of getting what you need).
There exist different classes of loadable modules:
Help with configuring/using