+ statsd: add hostname-override to statsd config options.

* This setting allows users to override the hostname used by
  Kamon when sending metrics to statsd.

3 files changed, 35 insertions, 1 deletions

diff --git a/kamon-statsd/src/main/resources/reference.conf b/kamon-statsd/src/main/resources/reference.conf
index f86052c1..c7229234 100644
--- a/kamon-statsd/src/main/resources/reference.conf
+++ b/kamon-statsd/src/main/resources/reference.conf
@@ -37,6 +37,10 @@ kamon {
       # will look as follows:
       #    application.entity.entity-name.metric-name
       include-hostname = true
+      # Allow users to override the name of the hostname reported by kamon. When changed, the scheme for the metrics
+      # will have the following pattern:
+      # application.myhostname.entity.entity-name.metric-name
+      hostname-override = "none"
     }
   }
 }
\ 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 76ef8d5f..a8d8ae48 100644
--- a/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
+++ b/kamon-statsd/src/main/scala/kamon/statsd/StatsD.scala
@@ -107,6 +107,9 @@ 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 hostnameOverride =
+    config.getString("kamon.statsd.simple-metric-key-generator.hostname-override")
+
   val _localhostName = ManagementFactory.getRuntimeMXBean.getName.split('@')(1)
   val _normalizedLocalhostName = _localhostName.replace('.', '_')
 
@@ -114,8 +117,12 @@ class SimpleMetricKeyGenerator(config: Config) extends StatsD.MetricKeyGenerator
 
   def normalizedLocalhostName: String = _normalizedLocalhostName
 
+  val hostname: String =
+    if (hostnameOverride == "none") normalizedLocalhostName
+    else hostnameOverride
+
   val baseName: String =
-    if (includeHostnameInMetrics) s"${application}.${normalizedLocalhostName}"
+    if (includeHostnameInMetrics) s"${application}.${hostname}"
     else application
 
   def generateKey(groupIdentity: MetricGroupIdentity, metricIdentity: MetricIdentity): String = {
diff --git a/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala b/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
index 5f3934a5..28ead7dc 100644
--- a/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
+++ b/kamon-statsd/src/test/scala/kamon/statsd/StatsDMetricSenderSpec.scala
@@ -39,6 +39,7 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
       |
       |  statsd {
       |    max-packet-size = 256 bytes
+      |    simple-metric-key-generator.hostname-override = "none"
       |  }
       |}
       |
@@ -51,6 +52,26 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
   val collectionContext = Kamon(Metrics).buildDefaultCollectionContext
 
   "the StatsDMetricSender" should {
+    "allows to override the hostname" in new UdpListenerFixture {
+      val config = ConfigFactory.parseString(
+        """
+        |kamon {
+        |  statsd {
+        |    simple-metric-key-generator.application = "api"
+        |    simple-metric-key-generator.hostname-override = "kamonhost"
+        |    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.kamonhost.trace.POST-_kamon_example.elapsed-time")
+    }
+
     "removes host name when attribute 'include-hostname' is set to false" in new UdpListenerFixture {
       val config = ConfigFactory.parseString(
         """
@@ -58,6 +79,7 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
         |  statsd {
         |    simple-metric-key-generator.application = "api"
         |    simple-metric-key-generator.include-hostname = false
+        |    simple-metric-key-generator.hostname-override = "none"
         |  }
         |}
         |
@@ -77,6 +99,7 @@ class StatsDMetricSenderSpec extends TestKitBase with WordSpecLike with Matchers
         |  statsd {
         |    simple-metric-key-generator.application = "api"
         |    simple-metric-key-generator.include-hostname = true
+        |    simple-metric-key-generator.hostname-override = "none"
         |  }
         |}
         |