Creating useful log files is a key part of building a useful, scalable and easy to manage software product. At Piwik recently we improved our logging backend, re-using monolog, and we've improve logging messages regularly in last releases.

To enable logging we point users to this FAQ: I’m a developer, how do I enable logging (and / or SQL profiling) in Piwik?. Currently, it is possible to debug the tracker by outputting results to the HTTP output (see this help).

The goal of this issue is to also provide a way for users to enable logging during Piwik Tracker (piwik.php API endpoint).

Steps:

• modify the printDebug function to reuse the monolog logger: https://github.com/piwik/piwik/blob/master/core/Common.php#L1260-1266
• add tests for tracker logger
• check FAQ is up to date: https://piwik.org/faq/troubleshooting/faq_115/
• add a note in http://developer.piwik.org/api-reference/tracking-api#debugging-the-tracker about how to enable logging for all tracker requests (with a link to previous faq)

Thoughts?