Regular Expression

Fluent Bit uses Onigmo regular expression library on Ruby mode, for testing purposes you can use the following web editor to test your expressions:

Important: do not attempt to add multiline support in your regular expressions if you are using Tail input plugin since each line is handled as a separated entity. Instead use Tail support configuration feature.

From a configuration perspective, when the format is set to regex, is mandatory and expected that a Regex configuration key exists.

The following parser configuration example aims to provide rules that can be applied to an Apache HTTP Server log entry:

The above content do not provide a defined structure for Fluent Bit, but enabling the proper parser we can help to make a structured representation of it:

A common pitfall is that you cannot use characters other than alphabets, numbers and underscore in group names. For example, a group name like will cause an error due to containing an invalid character (-).

In order to understand, learn and test regular expressions like the example above, we suggest you try the following Ruby Regular Expression Editor: http://rubular.com/r/X7BH0M4Ivm