+ play: external naming for traces and segments, related to #65

4 files changed, 38 insertions, 9 deletions

diff --git a/kamon-play/src/main/resources/reference.conf b/kamon-play/src/main/resources/reference.conf
index 72266a0c..5ad070ce 100644
--- a/kamon-play/src/main/resources/reference.conf
+++ b/kamon-play/src/main/resources/reference.conf
@@ -3,14 +3,24 @@
 # ================================== #
 
 kamon {
-  metrics {
-    tick-interval = 1 hour
-  }
-
   play {
-    include-trace-token-header = true
+
+    # Header name used when propagating the `TraceContext.token` value across applications.
     trace-token-header-name = "X-Trace-Token"
 
+    # When set to true, Kamon will automatically set and propogate the `TraceContext.token` value under the following
+    # conditions:
+    #  - When a server side request is received containing the trace token header, the new `TraceContext` will have that
+    #    some token, and once the response to that request is ready, the trace token header is also included in the
+    #    response.
+    #  - When a WS client request is issued and a `TraceContext` is available, the trace token header will be included
+    #    in the request headers.
+    automatic-trace-token-propagation = true
+
+    # Fully qualified name of the implementation of kamon.play.PlayNameGenerator that will be used for assigning names
+    # to traces and client http segments.
+    name-generator = kamon.play.DefaultPlayNameGenerator
+
     dispatcher = ${kamon.default-dispatcher}
   }
 }
\ No newline at end of file
diff --git a/kamon-play/src/main/scala/kamon/play/Play.scala b/kamon-play/src/main/scala/kamon/play/Play.scala
index 7b8777e0..6e2de3c1 100644
--- a/kamon-play/src/main/scala/kamon/play/Play.scala
+++ b/kamon-play/src/main/scala/kamon/play/Play.scala
@@ -21,6 +21,8 @@ import akka.event.Logging
 import kamon.Kamon
 import kamon.http.HttpServerMetrics
 import kamon.metric.Metrics
+import play.api.libs.ws.WSRequest
+import play.api.mvc.RequestHeader
 
 object Play extends ExtensionId[PlayExtension] with ExtensionIdProvider {
   override def lookup(): ExtensionId[_ <: Extension] = Play
@@ -35,7 +37,22 @@ class PlayExtension(private val system: ExtendedActorSystem) extends Kamon.Exten
 
   val httpServerMetrics = Kamon(Metrics)(system).register(HttpServerMetrics, HttpServerMetrics.Factory).get
   val defaultDispatcher = system.dispatchers.lookup(config.getString("dispatcher"))
-  val includeTraceToken: Boolean = config.getBoolean("include-trace-token-header")
+  val includeTraceToken: Boolean = config.getBoolean("automatic-trace-token-propagation")
   val traceTokenHeaderName: String = config.getString("trace-token-header-name")
+
+  private val nameGeneratorFQN = config.getString("name-generator")
+  private val nameGenerator: PlayNameGenerator = system.dynamicAccess.createInstanceFor[PlayNameGenerator](nameGeneratorFQN, Nil).get
+
+  def generateTraceName(requestHeader: RequestHeader): String = nameGenerator.generateTraceName(requestHeader)
+  def generateHttpClientSegmentName(request: WSRequest): String = nameGenerator.generateHttpClientSegmentName(request)
 }
 
+trait PlayNameGenerator {
+  def generateTraceName(requestHeader: RequestHeader): String
+  def generateHttpClientSegmentName(request: WSRequest): String
+}
+
+class DefaultPlayNameGenerator extends PlayNameGenerator {
+  def generateTraceName(requestHeader: RequestHeader): String = requestHeader.method + ": " + requestHeader.uri
+  def generateHttpClientSegmentName(request: WSRequest): String = request.url
+}
diff --git a/kamon-play/src/main/scala/kamon/play/instrumentation/RequestInstrumentation.scala b/kamon-play/src/main/scala/kamon/play/instrumentation/RequestInstrumentation.scala
index 82a43926..ca95781e 100644
--- a/kamon-play/src/main/scala/kamon/play/instrumentation/RequestInstrumentation.scala
+++ b/kamon-play/src/main/scala/kamon/play/instrumentation/RequestInstrumentation.scala
@@ -42,7 +42,7 @@ class RequestInstrumentation {
   def beforeRouteRequest(requestHeader: RequestHeader): Unit = {
     val system = Akka.system()
     val playExtension = Kamon(Play)(system)
-    val defaultTraceName: String = s"${requestHeader.method}: ${requestHeader.uri}"
+    val defaultTraceName = playExtension.generateTraceName(requestHeader)
 
     val token = if (playExtension.includeTraceToken) {
       requestHeader.headers.toSimpleMap.find(_._1 == playExtension.traceTokenHeaderName).map(_._2)
diff --git a/kamon-play/src/main/scala/kamon/play/instrumentation/WSInstrumentation.scala b/kamon-play/src/main/scala/kamon/play/instrumentation/WSInstrumentation.scala
index c2eafa2b..125db85e 100644
--- a/kamon-play/src/main/scala/kamon/play/instrumentation/WSInstrumentation.scala
+++ b/kamon-play/src/main/scala/kamon/play/instrumentation/WSInstrumentation.scala
@@ -34,8 +34,10 @@ class WSInstrumentation {
   @Around("onExecuteRequest(request)")
   def aroundExecuteRequest(pjp: ProceedingJoinPoint, request: WSRequest): Any = {
     TraceRecorder.withTraceContextAndSystem { (ctx, system) ⇒
-      val executor = Kamon(Play)(system).defaultDispatcher
-      val segment = ctx.startSegment(request.url, SegmentMetricIdentityLabel.HttpClient)
+      val playExtension = Kamon(Play)(system)
+      val executor = playExtension.defaultDispatcher
+      val segmentName = playExtension.generateHttpClientSegmentName(request)
+      val segment = ctx.startSegment(segmentName, SegmentMetricIdentityLabel.HttpClient)
       val response = pjp.proceed().asInstanceOf[Future[WSResponse]]
 
       response.map(result ⇒ segment.finish())(executor)