Configure and initialise tracer

Includes config options for the tracer and sets up JaegerClient.

synapse/app/_base.py

@@ -278,6 +278,9 @@ def start(hs, listeners=None):
         # Load the certificate from disk.
         refresh_certificate(hs)
 
+        # Start the tracer
+        synapse.config.tracer.init_tracing(hs.config)
+
         # It is now safe to start your Synapse.
         hs.start_listening(listeners)
         hs.get_datastore().start_profiling()

synapse/config/homeserver.py

@@ -40,6 +40,7 @@ from .spam_checker import SpamCheckerConfig
 from .stats import StatsConfig
 from .third_party_event_rules import ThirdPartyRulesConfig
 from .tls import TlsConfig
+from .tracer import TracerConfig
 from .user_directory import UserDirectoryConfig
 from .voip import VoipConfig
 from .workers import WorkerConfig
@@ -75,5 +76,6 @@ class HomeServerConfig(
     ServerNoticesConfig,
     RoomDirectoryConfig,
     ThirdPartyRulesConfig,
+    TracerConfig,
 ):
     pass

synapse/config/tracer.py

@@ -0,0 +1,80 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# 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.
+
+from ._base import Config
+from jaeger_client import Config as JaegerConfig
+from synapse.util.scopecontextmanager import LogContextScopeManager
+
+import logging
+logger = logging.getLogger(__name__)
+
+class TracerConfig(Config):
+    def read_config(self, config):
+        self.tracer_config = config.get("tracer")
+
+        if self.tracer_config is None:
+            # If the tracer is not configured we assume it is disabled
+            self.tracer_config = {
+                "tracer_enabled": False,
+            }
+        
+        if not self.tracer_config.get("tracer_enabled", False):
+            # The tracer is enabled so sanitize the config
+            # If no whitelists are given 
+            self.tracer_config.setdefault("user_whitelist", ["*"])
+            self.tracer_config.setdefault("homeserver_whitelist", ["*"])
+
+            if type(self.tracer_config.get("user_whitelist")) != list:
+                raise RuntimeError("Tracer user_whitelist config is malformed")
+            if type(self.tracer_config.get("homeserver_whitelist")) != list:
+                raise RuntimeError("Tracer homesererver_whitelist config is malformed")
+
+    def default_config(self, **kwargs):
+        return """\
+        ## Tracert ##
+
+        tracer:
+          # The list of users who's requests will be traced
+          # The list is a list of regex which is matched against the user_id
+          user_whitelist:
+            - "*"
+          # The list of homeservers we wish to trace across 
+          # The list is a list of regex which is matched against the homeserver name
+          homeserver_whitelist:
+            - "*"
+        """
+
+def init_tracing(config):
+    """Initialise the JaegerClient tracer
+
+    Args:
+        config (Config)
+        The config used by the homserver. Here it's used to set the service
+        name to the homeserver's.
+    """
+
+    jaeger_config = JaegerConfig(
+        config={ 
+            'sampler': {
+                'type': 'const',
+                'param': 1,
+            },
+            'logging': True,
+        },
+        service_name=config.server_name + "_new",
+        scope_manager=LogContextScopeManager(config),
+    )
+
+    return jaeger_config.initialize_tracer()