Adding a dual fallback log handler that

will be monkey patched in to replace the
base handler. That patching isn't quite
there yet but WIP.

1 files changed, 74 insertions, 0 deletions

diff --git a/cloudinit/monkey_patch.py b/cloudinit/monkey_patch.py
new file mode 100644
index 00000000..24b472ba
--- /dev/null
+++ b/cloudinit/monkey_patch.py
@@ -0,0 +1,74 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Canonical Ltd.
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Scott Moser <scott.moser@canonical.com>
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    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 logging
+import sys
+
+FALL_FORMAT = 'FALLBACK: %(asctime)s - %(filename)s[%(levelname)s]: %(message)s'
+
+Handler = logging.Handler
+
+class QuietStreamHandler(Handler):
+    def handleError(self, record):
+        pass
+
+
+class FallbackHandler(Handler):
+    def __init__(self, level=logging.NOTSET, fb_handler=None):
+        super(FallbackHandler, self).__init__(level)
+        if not fb_handler:
+            self.fallback_handler = QuietStreamHandler(sys.stderr)
+        else:
+            self.fallback_handler = fb_handler
+        self.fallback_handler.setFormatter(logging.Formatter(FALL_FORMAT))
+        self.fallback_handler.setLevel(level)
+
+    def flush(self):
+        super(FallbackHandler, self).flush()
+        self.fallback_handler.flush()
+
+    def close(self):
+        super(FallbackHandler, self).close(self)
+        self.fallback_handler.close()
+
+    def setLevel(self, level):
+        super(FallbackHandler, self).setLevel(self, level)
+        self.fallback_logger.setLevel(level)
+
+    def handleError(self, record):
+        try:
+            self.fallback_logger.handle(record)
+            # Always ensure this one is flushed...
+            self.fallback_logger.flush()
+        except:
+            pass
+
+
+def _patch_logging():
+    # Replace handler 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
+    logging.Handler = FallbackHandler
+
+
+def patch():
+    _patch_logging()