config: Add logging/config_file

docs/config.rst

@@ -97,6 +97,12 @@ Core configuration values
     The file to dump debug log data to when Mopidy is run with the
     :option:`mopidy --save-debug-log` option.
 
+.. confval:: logging/config_file
+
+    Config file that overrides all logging settings, see `the Python
+    logging docs <http://docs.python.org/2/library/logging.config.html>`_
+    for details.
+
 .. confval:: loglevels/*
 
     The ``loglevels`` config section can be used to change the log level for

mopidy/config/__init__.py

@@ -15,6 +15,7 @@ _logging_schema = ConfigSchema('logging')
 _logging_schema['console_format'] = String()
 _logging_schema['debug_format'] = String()
 _logging_schema['debug_file'] = Path()
+_logging_schema['config_file'] = Path(optional=True)
 
 _loglevels_schema = LogLevelConfigSchema('loglevels')
 

mopidy/config/default.conf

@@ -2,6 +2,7 @@
 console_format = %(levelname)-8s %(message)s
 debug_format = %(levelname)-8s %(asctime)s [%(process)d:%(threadName)s] %(name)s\n  %(message)s
 debug_file = mopidy.log
+config_file =
 
 [loglevels]
 pykka = info

mopidy/utils/log.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 import logging
+import logging.config
 import logging.handlers
 
 from . import versioning
@@ -15,6 +16,9 @@ def setup_logging(config, verbosity_level, save_debug_log):
         # New in Python 2.7
         logging.captureWarnings(True)
 
+    if config['logging']['config_file']:
+        logging.config.fileConfig(config['logging']['config_file'])
+
     logger = logging.getLogger('mopidy.utils.log')
     logger.info('Starting Mopidy %s', versioning.get_version())