Adding format_logger from teeth_overlord

teeth_agent/logging.py

@@ -14,10 +14,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 """
 
-import traceback
+import string
 
 import structlog
 
+import traceback
+
 EXCEPTION_LOG_METHODS = ['error']
 
 
@@ -28,9 +30,35 @@ def _capture_stack_trace(logger, method, event):
     return event
 
 
+def _format_event(logger, method, event):
+    """Formats the log message using keyword args.
+    log('hello {keyword}', keyword='world') should log: "hello world"
+    Removes the keywords used for formatting from the logged message.
+    Throws a KeyError if the log message requires formatting but doesn't
+    have enough keys to format.
+    """
+    if 'event' not in event:
+        # nothing to format, e.g. _log_request in teeth_rest/component
+        return event
+    # Get a list of fields that need to be filled.
+    formatter = string.Formatter()
+    try:
+        formatted = formatter.format(event['event'], **event)
+    except KeyError:
+        keys = formatter.parse(event['event'])
+        # index 1 is the key name
+        keys = [item[1] for item in keys]
+        missing_keys = list(set(keys) - set(event))
+        raise KeyError("Log formatter missing keys: {}, cannot format."
+                       .format(missing_keys))
+    event['event'] = formatted
+    return event
+
+
 def configure(pretty=False):
     processors = [
         _capture_stack_trace,
+        _format_event,
     ]
 
     if pretty:

teeth_agent/tests/logging.py

@@ -0,0 +1,44 @@
+"""
+Copyright 2013 Rackspace, Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+import structlog
+import unittest
+
+import teeth_agent.logging
+
+
+def _return_event_processor(logger, method, event):
+    return event['event']
+
+
+class EventLogger(unittest.TestCase):
+    def test_format_event_basic(self):
+        processors = [teeth_agent.logging._format_event,
+                      _return_event_processor]
+        structlog.configure(processors=processors)
+        log = structlog.wrap_logger(structlog.ReturnLogger())
+        logged_msg = log.msg("hello {word}", word='world')
+        self.assertEqual(logged_msg, "hello world")
+
+    def test_no_format_keys(self):
+        """Check that we get an exception if you don't provide enough keys to
+        format a log message requiring format
+        """
+        processors = [teeth_agent.logging._format_event,
+                      _return_event_processor]
+        structlog.configure(processors=processors)
+        log = structlog.wrap_logger(structlog.ReturnLogger())
+        self.assertRaises(KeyError, log.msg, "hello {word}")