When Joni, the regex engine that powers grok emits a warning it
does so by default to System.err. System.err logs are all bucketed
together in the server log at WARN level. When Joni emits a warning,
it can be extremely verbose, logging a message for each execution
again that pattern. For ingest node that means for every document
that is run that through Grok. Fortunately, Joni provides a call
back hook to push these warnings to a custom location.
This commit implements Joni's callback hook to push the Joni warning
to the Elasticsearch server logger (logger.org.elasticsearch.ingest.common.GrokProcessor)
at debug level. Generally these warning indicate a possible issue with
the regular expression and upon creation of the Grok processor will
do a "test run" of the expression and log the result (if any) at WARN
level. This WARN level log should only occur on pipeline creation which
is a much lower frequency then every document.
Additionally, the documentation is updated with instructions for how
to set the logger to debug level.
The documentation contained a small error, as bytes and duration was not
properly converted to a number and thus remained a string.
The documentation is now also properly tested by providing a full blown
simulate pipeline example.
As mapping types are being removed throughout Elasticsearch, the use of
`_type` in pipeline simulation requests is deprecated. Additionally, the
default `_type` used if one is not supplied has been changed to `_doc` for
consistency with the rest of Elasticsearch.
This commit breaks the single ingest docs file into multiple files,
factoring out the processor docs into a documentation file per
processor. This will help make this content easier to maintain.