GELF stands for the Graylog Extended Logging Format.
It is an open standard logging format based on JSON. It is primarily used to pipe messages to Graylog, the open source log management and analysis platform.
Using GELF avoids the shortcomings of logging to plain syslog, most importantly the lack of a structured payload along with messages (stack traces, timeouts etc).
GELF is a pure JSON format. It describes how log messages should be structured. In addition, it also describes compression of messages and chunking of large messages over UDP.
This module aims to provide a simple, yet structured, way of generating log messages in the GELF format. You can combine messages with arbitrary payload data and construct messages in multiple parts. Message contents are also queryable.