Make logging configurable through config file

http2irc.py

@@ -8,13 +8,11 @@ import logging
 import os.path
 import signal
 import ssl
+import string
 import sys
 import toml
 
 
-logging.basicConfig(level = logging.DEBUG, format = '{asctime} {levelname} {message}', style = '{')
-
-
 SSL_CONTEXTS = {'yes': True, 'no': False, 'insecure': ssl.SSLContext()}
 
 
@@ -56,10 +54,24 @@ class Config(dict):
 		logging.info(repr(obj))
 
 		# Sanity checks
-		if any(x not in ('irc', 'web', 'maps') for x in obj.keys()):
+		if any(x not in ('logging', 'irc', 'web', 'maps') for x in obj.keys()):
 			raise InvalidConfig('Unknown sections found in base object')
 		if any(not isinstance(x, collections.abc.Mapping) for x in obj.values()):
 			raise InvalidConfig('Invalid section type(s), expected objects/dicts')
+		if 'logging' in obj:
+			if any(x not in ('level', 'format') for x in obj['logging']):
+				raise InvalidConfig('Unknown key found in log section')
+			if 'level' in obj['logging'] and obj['logging']['level'] not in ('DEBUG', 'INFO', 'WARNING', 'ERROR'):
+				raise InvalidConfig('Invalid log level')
+			if 'format' in obj['logging']:
+				if not isinstance(obj['logging']['format'], str):
+					raise InvalidConfig('Invalid log format')
+				try:
+					#TODO: Replace with logging.Formatter's validate option (3.8+); this test does not cover everything that could be wrong (e.g. invalid format spec or conversion)
+					# This counts the number of replacement fields. Formatter.parse yields tuples whose second value is the field name; if it's None, there is no field (e.g. literal text).
+					assert sum(1 for x in string.Formatter().parse(obj['logging']['format']) if x[1] is not None) > 0
+				except (ValueError, AssertionError) as e:
+					raise InvalidConfig('Invalid log format: parsing failed') from e
 		if 'irc' in obj:
 			if any(x not in ('host', 'port', 'ssl', 'nick', 'real', 'certfile', 'certkeyfile') for x in obj['irc']):
 				raise InvalidConfig('Unknown key found in irc section')
@@ -107,7 +119,7 @@ class Config(dict):
 				#TODO: Check values
 
 		# Default values
-		finalObj = {'irc': {'host': 'irc.hackint.org', 'port': 6697, 'ssl': 'yes', 'nick': 'h2ibot', 'real': 'I am an http2irc bot.', 'certfile': None, 'certkeyfile': None}, 'web': {'host': '127.0.0.1', 'port': 8080}, 'maps': {}}
+		finalObj = {'logging': {'level': 'INFO', 'format': '{asctime} {levelname} {message}'}, 'irc': {'host': 'irc.hackint.org', 'port': 6697, 'ssl': 'yes', 'nick': 'h2ibot', 'real': 'I am an http2irc bot.', 'certfile': None, 'certkeyfile': None}, 'web': {'host': '127.0.0.1', 'port': 8080}, 'maps': {}}
 
 		# Fill in default values for the maps
 		for key, map_ in obj['maps'].items():
@@ -119,13 +131,13 @@ class Config(dict):
 				map_['auth'] = False
 
 		# Merge in what was read from the config file and set keys on self
-		for key in ('irc', 'web', 'maps'):
+		for key in ('logging', 'irc', 'web', 'maps'):
 			if key in obj:
 				finalObj[key].update(obj[key])
 			self[key] = finalObj[key]
 
 	def __repr__(self):
-		return f'<Config(irc={self["irc"]!r}, web={self["web"]!r}, maps={self["maps"]!r})>'
+		return f'<Config(logging={self["logging"]!r}, irc={self["irc"]!r}, web={self["web"]!r}, maps={self["maps"]!r})>'
 
 	def reread(self):
 		return Config(self._filename)
@@ -412,12 +424,24 @@ class WebServer:
 		raise aiohttp.web.HTTPOk()
 
 
+def configure_logging(config):
+	#TODO: Replace with logging.basicConfig(..., force = True) (Py 3.8+)
+	root = logging.getLogger()
+	root.setLevel(getattr(logging, config['logging']['level']))
+	root.handlers = [] #FIXME: Undocumented attribute of logging.Logger
+	formatter = logging.Formatter(config['logging']['format'], style = '{')
+	stderrHandler = logging.StreamHandler()
+	stderrHandler.setFormatter(formatter)
+	root.addHandler(stderrHandler)
+
+
 async def main():
 	if len(sys.argv) != 2:
 		print('Usage: http2irc.py CONFIGFILE', file = sys.stderr)
 		sys.exit(1)
 	configFile = sys.argv[1]
 	config = Config(configFile)
+	configure_logging(config)
 
 	loop = asyncio.get_running_loop()
 
@@ -442,6 +466,7 @@ async def main():
 			logging.error(f'Config reload failed: {e!s}')
 			return
 		config = newConfig
+		configure_logging(config)
 		irc.update_config(config)
 		webserver.update_config(config)
 	loop.add_signal_handler(signal.SIGUSR1, sigusr1_callback)