Looking to add some meta to the log data for easier searching. For instance, data from servers or a particular office location based on ip space?
You can add arbitrary data within Processing Pipeline rules: http://docs.graylog.org/en/2.2/pages/pipelines.html
Graylog 2.3.x will also add a generic lookup mechanism to run lookups in external systems, so that you could query your CMDB for item data and add it as additional fields to your messages.
Thank you much. Just wanted to make sure this was the way to do it.