Don't attempt to lookup the ip address if specified via a tag

This matches the functionality of jaeger-client-java after
jaegertracing/jaeger-client-java#371 was merged.

Refs: jaegertracing#166

jaeger_client/tracer.py

@@ -53,7 +53,6 @@ def __init__(
         self.service_name = service_name
         self.reporter = reporter
         self.sampler = sampler
-        self.ip_address = ipv4_to_int(local_ip())
         self.metrics_factory = metrics_factory or LegacyMetricsFactory(metrics or Metrics())
         self.metrics = TracerMetrics(self.metrics_factory)
         self.random = random.Random(time.time() * (os.getpid() or 1))
@@ -80,11 +79,13 @@ def __init__(
             self.codecs.update(extra_codecs)
         self.tags = {
             constants.JAEGER_VERSION_TAG_KEY: constants.JAEGER_CLIENT_VERSION,
-            constants.JAEGER_IP_TAG_KEY: self.ip_address,
         }
         if tags:
             self.tags.update(tags)
 
+        if self.tags.get(constants.JAEGER_IP_TAG_KEY) is None:
+            self.tags[constants.JAEGER_IP_TAG_KEY] = ipv4_to_int(local_ip())
+
         if self.tags.get(constants.JAEGER_HOSTNAME_TAG_KEY) is None:
             try:
                 hostname = socket.gethostname()

tests/test_tracer.py

@@ -262,6 +262,7 @@ def test_tracer_override_codecs():
         assert tracer.codecs[Format.BINARY] == "overridden_binary_codec",\
                 "Binary format codec not overridden"
 
+
 def test_tracer_hostname_tag():
     reporter = mock.MagicMock()
     sampler = ConstSampler(True)
@@ -274,3 +275,17 @@ def test_tracer_hostname_tag():
 
     assert tracer.tags[c.JAEGER_HOSTNAME_TAG_KEY] == \
             'jaeger-client-app.local'
+
+
+def test_tracer_ip_tag():
+    reporter = mock.MagicMock()
+    sampler = ConstSampler(True)
+    tracer = Tracer(
+        service_name='x',
+        tags={c.JAEGER_IP_TAG_KEY: '192.0.2.3'},
+        reporter=reporter,
+        sampler=sampler,
+    )
+
+    assert tracer.tags[c.JAEGER_IP_TAG_KEY] == \
+            '192.0.2.3'