Current maintainer: whitehouse
The Logger module provides event logging facilities that are decoupled from any particular storage backend. It is useful for module developers who want to instrument their code for monitoring and alerting without forcing their users to use a particular backend technology, like StatsD. The module doesn't provide any visible functionality out-of-the-box. You only need it if you're a module developer looking to instrument your code or if a module you're using depends on it.
Logger itself is installed in the usual way. See Installing contributed
modules.
An implementation of hook_logger_event() is required to connect to a logging
backend so as to actually do something with event data. See [logger.api.php]
(logger.api.php). This implementation may be supplied in custom code or by a
contributed module like StatsD.
Instrumentation is the process of adding "probes" to your application code to
fire events for Logger to log. If you're installing Logger as a dependency of
another module, presumably that module is already instrumented. To instrument
your own code, simply invoke logger_event(), much as you would [watchdog()]
(https://api.drupal.org/api/drupal/includes!bootstrap.inc/function/watchdog/7).
See logger.module.
If you're instrumenting a contributed module, you must declare a dependency on
Logger in your .info file.
Alternatively, you can create a "soft", or optional, dependency on Logger by
using a wrapping function instead of calling logger_event() directly, like
this:
function example_logger_event($name, $type = 'count', $value = 1) {
if (function_exists('logger_event')) {
logger_event($name, $type, $value);
}
}Event names should be Graphite-compatible,
i.e., paths delimited by dots (.). See
[Getting Your Data Into Graphite: Step 1]
(http://graphite.readthedocs.org/en/latest/feeding-carbon.html#step-1-plan-a-naming-hierarchy)
for some helpful advice.
Note: Logger has a debug mode that logs events to watchdog, which can be helpful
during development. It can be enabled at admin/config/development/logging or
by setting the logger_debug variable directly, e.g.:
# Enable debugging.
drush variable-set --exact logger_debug 1
# Disable debugging.
drush variable-delete --exact logger_debug