+ statsd: add the include-hostname setting to the default key generator

 * This commit adds 'include-hostname' the default key generator setting
   in statsd. When set to false, the generated keys wont include host
   information. They will have the following scheme:

   application.entity.entity-name.metric-name

3 files changed, 56 insertions, 10 deletions

diff --git a/kamon-statsd/src/main/resources/reference.conf b/kamon-statsd/src/main/resources/reference.conf
index eac5eade..f86052c1 100644
--- a/kamon-statsd/src/main/resources/reference.conf
+++ b/kamon-statsd/src/main/resources/reference.conf
@@ -33,6 +33,10 @@ kamon {
       # this pattern:
       #    application.host.entity.entity-name.metric-name
       application = "kamon"
+      # Includes the name of the hostname in the generated metric. When set to false, the scheme for the metrics
+      # will look as follows:
+      #    application.entity.entity-name.metric-name
+      include-hostname = true
     }
   }
 }
\ No newline at end of file
diff --git a/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala b/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
index ff273d9f..76ef8d5f 100644
--- a/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
+++ b/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
@@ -105,6 +105,8 @@ class StatsDExtension(system: ExtendedActorSystem) extends Kamon.Extension {
 
 class SimpleMetricKeyGenerator(config: Config) extends StatsD.MetricKeyGenerator {
   val application = config.getString("kamon.statsd.simple-metric-key-generator.application")
+  val includeHostnameInMetrics =
+    config.getBoolean("kamon.statsd.simple-metric-key-generator.include-hostname")
   val _localhostName = ManagementFactory.getRuntimeMXBean.getName.split('@')(1)
   val _normalizedLocalhostName = _localhostName.replace('.', '_')
 
@@ -112,13 +114,16 @@ class SimpleMetricKeyGenerator(config: Config) extends StatsD.MetricKeyGenerator
 
   def normalizedLocalhostName: String = _normalizedLocalhostName
 
+  val baseName: String =
+    if (includeHostnameInMetrics) s"${application}.${normalizedLocalhostName}"
+    else application
+
   def generateKey(groupIdentity: MetricGroupIdentity, metricIdentity: MetricIdentity): String = {
     val normalizedGroupName = groupIdentity.name.replace(": ", "-").replace(" ", "_").replace("/", "_")
+    val key = s"${baseName}.${groupIdentity.category.name}.${normalizedGroupName}"
 
-    if (isUserMetric(groupIdentity))
-      s"${application}.${normalizedLocalhostName}.${groupIdentity.category.name}.${normalizedGroupName}"
-    else
-      s"${application}.${normalizedLocalhostName}.${groupIdentity.category.name}.${normalizedGroupName}.${metricIdentity.name}"
+    if (isUserMetric(groupIdentity)) key
+    else s"${key}.${metricIdentity.name}"
   }
 
   def isUserMetric(groupIdentity: MetricGroupIdentity): Boolean = groupIdentity match {
@@ -126,4 +131,3 @@ class SimpleMetricKeyGenerator(config: Config) extends StatsD.MetricKeyGenerator
     case everythingElse                  ⇒ false
   }
 }
-
diff --git a/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala b/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
index 3bc1364c..5f3934a5 100644
--- a/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
+++ b/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
@@ -44,9 +44,51 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
       |
     """.stripMargin))
 
+  implicit val metricKeyGenerator = new SimpleMetricKeyGenerator(system.settings.config) {
+    override def normalizedLocalhostName: String = "localhost_local"
+  }
+
   val collectionContext = Kamon(Metrics).buildDefaultCollectionContext
 
   "the StatsDMetricSender" should {
+    "removes host name when attribute 'include-hostname' is set to false" in new UdpListenerFixture {
+      val config = ConfigFactory.parseString(
+        """
+        |kamon {
+        |  statsd {
+        |    simple-metric-key-generator.application = "api"
+        |    simple-metric-key-generator.include-hostname = false
+        |  }
+        |}
+        |
+        """.stripMargin)
+      implicit val metricKeyGenerator = new SimpleMetricKeyGenerator(config) {
+        override def normalizedLocalhostName: String = "localhost_local"
+      }
+
+      val testMetricKey = buildMetricKey("trace", "POST: /kamon/example", "elapsed-time")
+      testMetricKey should be(s"api.trace.POST-_kamon_example.elapsed-time")
+    }
+
+    "uses aplication prefix when present" in new UdpListenerFixture {
+      val config = ConfigFactory.parseString(
+        """
+        |kamon {
+        |  statsd {
+        |    simple-metric-key-generator.application = "api"
+        |    simple-metric-key-generator.include-hostname = true
+        |  }
+        |}
+        |
+        """.stripMargin)
+      implicit val metricKeyGenerator = new SimpleMetricKeyGenerator(config) {
+        override def normalizedLocalhostName: String = "localhost_local"
+      }
+
+      val testMetricKey = buildMetricKey("trace", "POST: /kamon/example", "elapsed-time")
+      testMetricKey should be(s"api.localhost_local.trace.POST-_kamon_example.elapsed-time")
+    }
+
     "normalize the group entity name to remove spaces, colons and replace '/' with '_'" in new UdpListenerFixture {
       val testMetricKey = buildMetricKey("trace", "POST: /kamon/example", "elapsed-time")
       testMetricKey should be(s"kamon.localhost_local.trace.POST-_kamon_example.elapsed-time")
@@ -138,10 +180,6 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
 
   trait UdpListenerFixture {
     val testMaxPacketSize = system.settings.config.getBytes("kamon.statsd.max-packet-size")
-    val metricKeyGenerator = new SimpleMetricKeyGenerator(system.settings.config) {
-      override def normalizedLocalhostName: String = "localhost_local"
-    }
-
     val testGroupIdentity = new MetricGroupIdentity {
       val name: String = "/user/kamon"
       val category: MetricGroupCategory = new MetricGroupCategory {
@@ -149,7 +187,7 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
       }
     }
 
-    def buildMetricKey(categoryName: String, entityName: String, metricName: String): String = {
+    def buildMetricKey(categoryName: String, entityName: String, metricName: String)(implicit metricKeyGenerator: SimpleMetricKeyGenerator): String = {
       val metricIdentity = new MetricIdentity { val name: String = metricName }
       val groupIdentity = new MetricGroupIdentity {
         val name: String = entityName