Allow to set custom hostname for jaeger agent.

From
jaegertracing#51

jaeger_client/config.py

@@ -50,6 +50,7 @@
 from .metrics import Metrics
 from .utils import get_boolean, ErrorReporter
 
+DEFAULT_REPORTING_HOST = 'localhost'
 DEFAULT_REPORTING_PORT = 5775
 DEFAULT_SAMPLING_PORT = 5778
 LOCAL_AGENT_DEFAULT_ENABLED = True
@@ -212,6 +213,14 @@ def local_agent_reporting_port(self):
         except:
             return DEFAULT_REPORTING_PORT
 
+    @property
+    def local_agent_reporting_host(self):
+        # noinspection PyBroadException
+        try:
+            return self.local_agent_group()['reporting_host']
+        except:
+            return DEFAULT_REPORTING_HOST
+
     @property
     def max_operations(self):
         return self.config.get('max_operations', None)
@@ -293,7 +302,7 @@ def _create_local_agent_channel(self, io_loop):
         """
         logger.info('Initializing Jaeger Tracer with UDP reporter')
         return LocalAgentSender(
-            host='localhost',
+            host=self.local_agent_reporting_host,
             sampling_port=self.local_agent_sampling_port,
             reporting_port=self.local_agent_reporting_port,
             io_loop=io_loop