Merge lp:~harlowja/cloud-init/patch-handler into lp:~cloud-init-dev/cloud-init/trunk

[Joshua Harlow]

WIP!

[lp:~harlowja/cloud-init/patch-handler]

655. By Joshua Harlow on 2012-09-19

Get the fallback working.

656. By Joshua Harlow on 2012-09-19

First thing that we do after we can start importing
is to patch the functionality before it gets reimported.

=== modified file 'bin/cloud-init'
--- bin/cloud-init	2012-09-07 01:12:21 +0000
+++ bin/cloud-init	2012-09-19 23:12:20 +0000
@@ -33,6 +33,9 @@
 if os.path.exists(os.path.join(possible_topdir, "cloudinit", "__init__.py")):
     sys.path.insert(0, possible_topdir)
 
+from cloudinit import patcher
+patcher.patch()
+
 from cloudinit import log as logging
 from cloudinit import netinfo
 from cloudinit import signal_handler

=== added file 'cloudinit/patcher.py'
--- cloudinit/patcher.py	1970-01-01 00:00:00 +0000
+++ cloudinit/patcher.py	2012-09-19 23:12:20 +0000
@@ -0,0 +1,56 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Canonical Ltd.
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Scott Moser <[e-mail]>
+#    Author: Joshua Harlow <[e-mail]>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import imp
+import logging
+import sys
+
+# Default fallback format
+FALL_FORMAT = 'FALLBACK: %(asctime)s - %(filename)s[%(levelname)s]: %(message)s'
+
+
+class QuietStreamHandler(logging.StreamHandler):
+    def handleError(self, record):
+        pass
+
+
+def _patch_logging():
+    # Replace 'handleError' with one that will be more
+    # tolerant of errors in that it can avoid
+    # re-notifying on exceptions and when errors
+    # do occur, it can at least try to write to
+    # sys.stderr using a fallback logger
+    fallback_handler = QuietStreamHandler(sys.stderr)
+    fallback_handler.setFormatter(logging.Formatter(FALL_FORMAT))
+    def handleError(self, record):
+        try:
+            fallback_handler.handle(record)
+            fallback_handler.flush()
+        except IOError:
+            pass
+    setattr(logging.Handler, 'handleError', handleError)
+
+
+def patch():
+    imp.acquire_lock()
+    try:
+        _patch_logging()
+    finally:
+        imp.release_lock()