Handle driver initialization errors to avoid service crash

This patch fixes the issue when failed osprofiler driver brings
the whole service down. With this patch the default no-op behaviour
is used in case of initialization failure.

Change-Id: I6ebc393576f4fc3f8b4134164bafc2e09f102ebd

6 files changed, 45 insertions, 21 deletions

diff --git a/osprofiler/drivers/elasticsearch_driver.py b/osprofiler/drivers/elasticsearch_driver.py
index 85bab74..c24eb60 100644
--- a/osprofiler/drivers/elasticsearch_driver.py
+++ b/osprofiler/drivers/elasticsearch_driver.py
@@ -36,9 +36,9 @@ class ElasticsearchDriver(base.Driver):
             from elasticsearch import Elasticsearch
         except ImportError:
             raise exc.CommandError(
-                "To use this command, you should install "
-                "'elasticsearch' manually. Use command:\n "
-                "'pip install elasticsearch'.")
+                "To use OSProfiler with ElasticSearch driver, "
+                "please install `elasticsearch` library. "
+                "To install with pip:\n `pip install elasticsearch`.")
 
         client_url = parser.urlunparse(parser.urlparse(self.connection_str)
                                        ._replace(scheme="http"))
diff --git a/osprofiler/drivers/jaeger.py b/osprofiler/drivers/jaeger.py
index 669aa13..82b7a23 100644
--- a/osprofiler/drivers/jaeger.py
+++ b/osprofiler/drivers/jaeger.py
@@ -40,8 +40,8 @@ class Jaeger(base.Driver):
         except ImportError:
             raise exc.CommandError(
                 "To use OSProfiler with Uber Jaeger tracer, "
-                "you have to install `jaeger-client` manually. "
-                "Install with pip:\n `pip install jaeger-client`."
+                "please install `jaeger-client` library. "
+                "To install with pip:\n `pip install jaeger-client`."
             )
 
         parsed_url = parser.urlparse(connection_str)
diff --git a/osprofiler/drivers/mongodb.py b/osprofiler/drivers/mongodb.py
index 0ca1928..a0372f6 100644
--- a/osprofiler/drivers/mongodb.py
+++ b/osprofiler/drivers/mongodb.py
@@ -28,9 +28,9 @@ class MongoDB(base.Driver):
             from pymongo import MongoClient
         except ImportError:
             raise exc.CommandError(
-                "To use this command, you should install "
-                "'pymongo' manually. Use command:\n "
-                "'pip install pymongo'.")
+                "To use OSProfiler with MongoDB driver, "
+                "please install `pymongo` library. "
+                "To install with pip:\n `pip install pymongo`.")
 
         client = MongoClient(self.connection_str, connect=False)
         self.db = client[db_name]
diff --git a/osprofiler/drivers/redis_driver.py b/osprofiler/drivers/redis_driver.py
index 250a81c..0952702 100644
--- a/osprofiler/drivers/redis_driver.py
+++ b/osprofiler/drivers/redis_driver.py
@@ -40,9 +40,9 @@ class Redis(base.Driver):
             from redis import StrictRedis
         except ImportError:
             raise exc.CommandError(
-                "To use this command, you should install "
-                "'redis' manually. Use command:\n "
-                "'pip install redis'.")
+                "To use OSProfiler with Redis driver, "
+                "please install `redis` library. "
+                "To install with pip:\n `pip install redis`.")
 
         # only connection over network is supported with schema
         # redis://[:password]@host[:port][/db]
diff --git a/osprofiler/notifier.py b/osprofiler/notifier.py
index 3bd4412..8b909f0 100644
--- a/osprofiler/notifier.py
+++ b/osprofiler/notifier.py
@@ -13,16 +13,21 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import logging
+
 from osprofiler.drivers import base
 
 
+LOG = logging.getLogger(__name__)
+
+
 def _noop_notifier(info, context=None):
     """Do nothing on notify()."""
 
 
 # NOTE(boris-42): By default we are using noop notifier.
 __notifier = _noop_notifier
-__driver_cache = {}
+__notifier_cache = {}  # map: connection-string -> notifier
 
 
 def notify(info):
@@ -54,14 +59,24 @@ def create(connection_string, *args, **kwargs):
 
     :param connection_string: connection string which specifies the storage
                               driver for notifier
-    :param *args: args that will be passed to the driver's __init__ method
-    :param **kwargs: kwargs that will be passed to the driver's __init__ method
+    :param args: args that will be passed to the driver's __init__ method
+    :param kwargs: kwargs that will be passed to the driver's __init__ method
     :returns: Callable notifier method
-    :raises TypeError: In case of invalid name of plugin raises TypeError
     """
-    global __driver_cache
-    if connection_string not in __driver_cache:
-        __driver_cache[connection_string] = base.get_driver(connection_string,
-                                                            *args,
-                                                            **kwargs).notify
-    return __driver_cache[connection_string]
+    global __notifier_cache
+    if connection_string not in __notifier_cache:
+        try:
+            driver = base.get_driver(connection_string, *args, **kwargs)
+            __notifier_cache[connection_string] = driver.notify
+            LOG.info("osprofiler is enabled with connection string: %s",
+                     connection_string)
+        except Exception:
+            LOG.exception("Could not initialize driver for connection string "
+                          "%s, osprofiler is disabled", connection_string)
+            __notifier_cache[connection_string] = _noop_notifier
+
+    return __notifier_cache[connection_string]
+
+
+def clear_notifier_cache():
+    __notifier_cache.clear()
diff --git a/osprofiler/tests/unit/test_notifier.py b/osprofiler/tests/unit/test_notifier.py
index 7cccdad..8e658fe 100644
--- a/osprofiler/tests/unit/test_notifier.py
+++ b/osprofiler/tests/unit/test_notifier.py
@@ -23,6 +23,7 @@ class NotifierTestCase(test.TestCase):
 
     def tearDown(self):
         notifier.set(notifier._noop_notifier)  # restore defaults
+        notifier.clear_notifier_cache()
         super(NotifierTestCase, self).tearDown()
 
     def test_set(self):
@@ -49,3 +50,11 @@ class NotifierTestCase(test.TestCase):
         result = notifier.create("test", 10, b=20)
         mock_factory.assert_called_once_with("test", 10, b=20)
         self.assertEqual(mock_factory.return_value.notify, result)
+
+    @mock.patch("osprofiler.notifier.base.get_driver")
+    def test_create_driver_init_failure(self, mock_get_driver):
+        mock_get_driver.side_effect = Exception()
+
+        result = notifier.create("test", 10, b=20)
+        mock_get_driver.assert_called_once_with("test", 10, b=20)
+        self.assertEqual(notifier._noop_notifier, result)