Custom logging handler that cleans files on startup

src/octoprint/logging/__init__.py

@@ -0,0 +1,4 @@
+# coding=utf-8
+from __future__ import absolute_import
+
+from . import handlers

src/octoprint/logging/handlers.py

@@ -0,0 +1,16 @@
+# coding=utf-8
+from __future__ import absolute_import
+
+import logging.handlers
+import os
+
+class CleaningTimedRotatingFileHandler(logging.handlers.TimedRotatingFileHandler):
+
+	def __init__(self, *args, **kwargs):
+		logging.handlers.TimedRotatingFileHandler.__init__(self, *args, **kwargs)
+
+		# clean up old files on handler start
+		if self.backupCount > 0:
+			for s in self.getFilesToDelete():
+				os.remove(s)
+

src/octoprint/server/__init__.py

@@ -574,11 +574,11 @@ class Server(object):
 					"stream": "ext://sys.stdout"
 				},
 				"file": {
-					"class": "logging.handlers.TimedRotatingFileHandler",
+					"class": "octoprint.logging.handlers.CleaningTimedRotatingFileHandler",
 					"level": "DEBUG",
 					"formatter": "simple",
 					"when": "D",
-					"backupCount": "1",
+					"backupCount": 7,
 					"filename": os.path.join(settings().getBaseFolder("logs"), "octoprint.log")
 				},
 				"serialFile": {