Add a NullHandler to all of our loggers

As a library, it's important to make sure our logging is set up to not
be confusing, but also to not to step on the toes of app developers.

https://docs.python.org/3.1/library/logging.html#configuring-logging-for-a-library

Change-Id: I312871e057ca0f64b9c5514bc94567cbdb34b4c6

shade/__init__.py

@@ -51,6 +51,7 @@ import warnings
 warnings.filterwarnings('ignore', 'Certificate has no `subjectAltName`')
 
 from shade.exc import *  # noqa
+from shade import _log
 from shade import meta
 from shade import task_manager
 from shade import _tasks
@@ -106,7 +107,7 @@ def simple_logging(debug=False):
         log_level = logging.DEBUG
     else:
         log_level = logging.INFO
-    log = logging.getLogger('shade')
+    log = _log.setup_logging('shade')
     log.addHandler(logging.StreamHandler())
     log.setLevel(log_level)
 
@@ -220,7 +221,7 @@ class OpenStackCloud(object):
             cache_arguments=None,
             manager=None, **kwargs):
 
-        self.log = logging.getLogger('shade')
+        self.log = _log.setup_logging('shade')
         if not cloud_config:
             config = os_client_config.OpenStackConfig()
             cloud_config = config.get_one_cloud(**kwargs)

shade/_log.py

@@ -0,0 +1,28 @@
+# Copyright (c) 2015 IBM Corp.
+#
+# 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 logging
+
+
+class NullHandler(logging.Handler):
+    def emit(self, record):
+        pass
+
+
+def setup_logging(name):
+    log = logging.getLogger(name)
+    if len(log.handlers) == 0:
+        h = NullHandler()
+        log.addHandler(h)
+    return log

shade/exc.py

@@ -12,10 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import logging
 import sys
 
-log = logging.getLogger(__name__)
+from shade import _log
+
+log = _log.setup_logging(__name__)
 
 
 class OpenStackCloudException(Exception):

shade/meta.py

@@ -14,16 +14,16 @@
 
 
 import bunch
-import logging
 import six
 
 from shade import exc
+from shade import _log
 from shade import _utils
 
 
 NON_CALLABLES = (six.string_types, bool, dict, int, float, list, type(None))
 
-log = logging.getLogger(__name__)
+log = _log.setup_logging(__name__)
 
 
 def find_nova_addresses(addresses, ext_tag=None, key_name=None, version=4):

shade/task_manager.py

@@ -17,13 +17,14 @@
 # limitations under the License.
 
 import abc
-import logging
 import sys
 import threading
 import time
 
 import six
 
+from shade import _log
+
 
 @six.add_metaclass(abc.ABCMeta)
 class Task(object):
@@ -78,7 +79,7 @@ class Task(object):
 
 
 class TaskManager(object):
-    log = logging.getLogger("shade.TaskManager")
+    log = _log.setup_logging("shade.TaskManager")
 
     def __init__(self, client, name):
         self.name = name