make the remote parent join mode configurable

2 files changed, 11 insertions, 2 deletions

diff --git a/kamon-core/src/main/resources/reference.conf b/kamon-core/src/main/resources/reference.conf
index 06da8e18..cd8fa379 100644
--- a/kamon-core/src/main/resources/reference.conf
+++ b/kamon-core/src/main/resources/reference.conf
@@ -85,6 +85,13 @@ kamon {
     reporter-queue-size = 1024
 
 
+    # Decide whether a new, locally created Span should have the same Span Identifier as it's remote parent (if any) or
+    # get a new local identifier. Certain tracing systems use the same Span Identifier to represent both sides (client
+    # and server) of a RPC call, if you are reporting data to such systems then this option should be enabled.
+    #
+    # If you are using Zipkin, keep this option enabled. If you are using Jaeger, disable it.
+    join-remote-parents-with-same-span-id = true
+
     # Configures a sample that decides which traces should be reported to the trace backends. The possible values are:
     #   - always: report all traces.
     #   - never:  don't report any trace.
diff --git a/kamon-core/src/main/scala/kamon/trace/Tracer.scala b/kamon-core/src/main/scala/kamon/trace/Tracer.scala
index 1aa07be1..c10974f5 100644
--- a/kamon-core/src/main/scala/kamon/trace/Tracer.scala
+++ b/kamon-core/src/main/scala/kamon/trace/Tracer.scala
@@ -50,7 +50,7 @@ object Tracer {
     }
 
     private[Tracer] val tracerMetrics = new TracerMetrics(metrics)
-    @volatile private[Tracer] var joinRemoteSpansWithSameID: Boolean = false
+    @volatile private[Tracer] var joinRemoteParentsWithSameSpanID: Boolean = true
     @volatile private[Tracer] var configuredSampler: Sampler = Sampler.Never
     @volatile private[Tracer] var identityProvider: IdentityProvider = IdentityProvider.Default()
     @volatile private[Tracer] var textMapSpanContextCodec: SpanContextCodec[TextMap] = SpanContextCodec.ExtendedB3(identityProvider)
@@ -101,6 +101,8 @@ object Tracer {
         case "random" => Sampler.random(traceConfig.getDouble("random-sampler.probability"))
         case other    => sys.error(s"Unexpected sampler name $other.")
       }
+
+      joinRemoteParentsWithSameSpanID = traceConfig.getBoolean("join-remote-parents-with-same-span-id")
     }
   }
 
@@ -160,7 +162,7 @@ object Tracer {
     }
 
     private def joinParentContext(parent: SpanContext, samplingDecision: SamplingDecision): SpanContext =
-      if(parent.source == Source.Remote && tracer.joinRemoteSpansWithSameID)
+      if(parent.source == Source.Remote && tracer.joinRemoteParentsWithSameSpanID)
         parent.copy(samplingDecision = samplingDecision)
       else
         parent.createChild(tracer.identityProvider.spanIdentifierGenerator().generate(), samplingDecision)