Merge pull request #16 from diversit/feature/register-default-exporters

Added setting for automatic loading of default hotspot collectors

README.md

@@ -110,4 +110,12 @@ GET         /metrics          com.github.stijndehaes.playprometheusfilters.contr
 
 You should be able to immediately get the metrics
 
-## Example
+## Default Hotspot metrics
+
+The [Prometheus Hotspot library](https://github.com/prometheus/client_java#included-collectors) provides some default collectors
+for garbage collection, memory pool, etc.
+Default these collectors are _not_ registered. This can be changed by setting the configuration property to `true`.
+
+```
+play-prometheus-filters.register-default-hotspot-collectors = true
+```

app/com/github/stijndehaes/playprometheusfilters/PrometheusModule.scala

@@ -3,11 +3,24 @@ package com.github.stijndehaes.playprometheusfilters
 import play.api.inject.{Binding, Module}
 import play.api.{Configuration, Environment}
 import io.prometheus.client.CollectorRegistry
+import io.prometheus.client.hotspot._
+
+object PrometheusModule {
+  val defaultExportsKey = "play-prometheus-filters.register-default-hotspot-collectors"
+}
 
 class PrometheusModule extends Module {
+  import PrometheusModule._
 
   override def bindings(environment: Environment, configuration: Configuration): Seq[Binding[_]] = {
     CollectorRegistry.defaultRegistry.clear()
+
+    configuration.getOptional[Boolean](defaultExportsKey).foreach { enabled =>
+      if (enabled) {
+        DefaultExports.initialize()
+      }
+    }
+
     Seq(
       bind[CollectorRegistry].to(CollectorRegistry.defaultRegistry)
     )

build.sbt

@@ -37,14 +37,15 @@ lazy val root = (project in file("."))
         </developer>
       </developers>
   )
-scalaVersion := "2.12.5"
+scalaVersion := "2.12.6"
 
-crossScalaVersions := Seq(scalaVersion.value, "2.11.11")
+crossScalaVersions := Seq(scalaVersion.value, "2.11.12")
 
 libraryDependencies ++= Seq(
   guice,
-  "io.prometheus"             % "simpleclient"          % "0.3.0",
-  "io.prometheus"             % "simpleclient_servlet"  % "0.3.0"
+  "io.prometheus"             % "simpleclient"          % "0.5.0",
+  "io.prometheus"             % "simpleclient_hotspot"  % "0.5.0",
+  "io.prometheus"             % "simpleclient_servlet"  % "0.5.0"
 )
 
 libraryDependencies ++= Seq(

conf/reference.conf

@@ -1 +1,4 @@
-play.modules.enabled += com.github.stijndehaes.playprometheusfilters.PrometheusModule
+play.modules.enabled += com.github.stijndehaes.playprometheusfilters.PrometheusModule
+
+# Registers some default collectors for jvm metrics. See DefaultExports class.
+play-prometheus-filters.register-default-hotspot-collectors = false

project/plugins.sbt

@@ -1,5 +1,5 @@
 // The Play plugin
-addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.6.12")
+addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.6.18")
 
 addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "2.3")
 

test/com/github/stijndehaes/playprometheusfilters/PrometheusModuleSpec.scala

@@ -0,0 +1,52 @@
+package com.github.stijndehaes.playprometheusfilters
+
+import io.prometheus.client.CollectorRegistry
+import org.scalatest.{BeforeAndAfter, MustMatchers, WordSpec}
+import play.api.inject.guice.GuiceApplicationBuilder
+
+class PrometheusModuleSpec extends WordSpec with MustMatchers with BeforeAndAfter {
+
+  before {
+    // clearing registry before each test
+    CollectorRegistry.defaultRegistry.clear()
+  }
+
+  "PrometheusModule" should {
+    "register default exporters when enabled" in {
+      // default enabled
+      val app = new GuiceApplicationBuilder()
+        .configure(PrometheusModule.defaultExportsKey -> true)
+        .build()
+
+      val collector = app.injector.instanceOf[CollectorRegistry]
+      collector.getExporterNames.size must be > 0
+    }
+
+    "not register default exporters when disabled" in {
+      // disable default exporters
+      val app = new GuiceApplicationBuilder()
+        .configure(PrometheusModule.defaultExportsKey -> false)
+        .build()
+
+      val collector = app.injector.instanceOf[CollectorRegistry]
+      collector.getExporterNames.size must be (0)
+    }
+  }
+
+  /**
+    * Utility to expose exporter names for test on [[CollectorRegistry]].
+    */
+  implicit class CollectorRegistryExtention(val registry: CollectorRegistry) {
+    /**
+      * @return Registered exporter names.
+      */
+    def getExporterNames: Seq[String] = {
+      val exportNames = collection.mutable.Buffer.empty[String]
+      val mfs = registry.metricFamilySamples()
+      while(mfs.hasMoreElements) {
+        exportNames += mfs.nextElement().name
+      }
+      exportNames
+    }
+  }
+}