1 files changed, 52 insertions, 0 deletions
diff --git a/kamon-examples/kamon-play-example/app/filters/TraceLocalFilter.scala b/kamon-examples/kamon-play-example/app/filters/TraceLocalFilter.scala
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+++ b/kamon-examples/kamon-play-example/app/filters/TraceLocalFilter.scala
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+/* ===================================================
+ * Copyright © 2013-2014 the kamon project <http://kamon.io/>
+ *
+ * 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.
+ * ========================================================== */
+
+package filters
+
+import kamon.trace.{TraceRecorder, TraceLocal}
+import play.api.Logger
+import play.api.mvc.{Result, RequestHeader, Filter}
+import play.api.libs.concurrent.Execution.Implicits.defaultContext
+import scala.concurrent.Future
+
+object TraceLocalKey extends TraceLocal.TraceLocalKey {
+  type ValueType = String
+}
+
+/*
+ By default Kamon spreads the trace-token-header-name but sometimes is necessary pass through the application requests with some infomation like
+ extra headers, with kamon it's possible using TraceLocalStorage, in Play applications we can do an Action Filter or using Action Composition,
+ in this example we are using a simple filter where given a Header store the value and then put the value in the result headers..
+
+ More detailed usage of TraceLocalStorage: https://github.com/kamon-io/Kamon/blob/b17539d231da923ea854c01d2c69eb02ef1e85b1/kamon-core/src/test/scala/kamon/trace/TraceLocalSpec.scala
+ */
+object TraceLocalFilter extends Filter {
+  val logger = Logger(this.getClass)
+  val TraceLocalStorageKey = "MyTraceLocalStorageKey"
+
+  override def apply(next: (RequestHeader) ⇒ Future[Result])(header: RequestHeader): Future[Result] = {
+    TraceRecorder.withTraceContext(TraceRecorder.currentContext) {
+
+      TraceLocal.store(TraceLocalKey)(header.headers.get(TraceLocalStorageKey).getOrElse("unknown"))
+
+      next(header).map {
+        val traceTokenValue = TraceLocal.retrieve(TraceLocalKey).getOrElse("unknown")
+        logger.info(s"traceTokenValue: $traceTokenValue")
+        result ⇒ result.withHeaders((TraceLocalStorageKey -> traceTokenValue))
+      }
+    }
+  }
+}