From 008283e63e01d67cfdaee6976474a5272a0b1e91 Mon Sep 17 00:00:00 2001
From: vlad <vlad@drivergrp.com>
Date: Wed, 12 Oct 2016 13:00:29 -0700
Subject: App /health endpoint with info related to OS, memory, file system and
 GC

---
 src/main/scala/com/drivergrp/core/app.scala   | 35 ++++++++++++++++-
 src/main/scala/com/drivergrp/core/stats.scala | 54 +++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/main/scala/com/drivergrp/core/app.scala b/src/main/scala/com/drivergrp/core/app.scala
index a1e1082..f6100f0 100644
--- a/src/main/scala/com/drivergrp/core/app.scala
+++ b/src/main/scala/com/drivergrp/core/app.scala
@@ -11,6 +11,7 @@ import akka.http.scaladsl.server.{ExceptionHandler, Route, RouteConcatenation}
 import akka.stream.ActorMaterializer
 import com.drivergrp.core.logging.{Logger, TypesafeScalaLogger}
 import com.drivergrp.core.rest.Swagger
+import com.drivergrp.core.stats.SystemStats
 import com.drivergrp.core.time.Time
 import com.drivergrp.core.time.provider.{SystemTimeProvider, TimeProvider}
 import com.typesafe.config.Config
@@ -99,7 +100,7 @@ object app {
 
       val _ = Future {
         http.bindAndHandle(route2HandlerFlow(handleExceptions(generalExceptionHandler) {
-          logRequestResult("log")(modules.map(_.route).foldLeft(versionRt ~ swaggerRoutes)(_ ~ _))
+          logRequestResult("log")(modules.map(_.route).foldLeft(versionRt ~ healthRoute ~ swaggerRoutes)(_ ~ _))
         }), interface, port)(materializer)
       }
     }
@@ -122,6 +123,38 @@ object app {
       }
     }
 
+    protected def healthRoute: Route = {
+      import DefaultJsonProtocol._
+      import SprayJsonSupport._
+      import spray.json._
+
+      val memoryUsage = SystemStats.memoryUsage
+      val gcStats     = SystemStats.garbageCollectorStats
+
+      path("health") {
+        complete(
+            Map(
+                "availableProcessors" -> SystemStats.availableProcessors.toJson,
+                "memoryUsage" -> Map(
+                    "free"  -> memoryUsage.free.toJson,
+                    "total" -> memoryUsage.total.toJson,
+                    "max"   -> memoryUsage.max.toJson
+                ).toJson,
+                "gcStats" -> Map(
+                    "garbageCollectionTime"   -> gcStats.garbageCollectionTime.toJson,
+                    "totalGarbageCollections" -> gcStats.totalGarbageCollections.toJson
+                ).toJson,
+                "fileSystemSpace" -> SystemStats.fileSystemSpace.map { f =>
+              Map("path"        -> f.path.toJson,
+                  "freeSpace"   -> f.freeSpace.toJson,
+                  "totalSpace"  -> f.totalSpace.toJson,
+                  "usableSpace" -> f.usableSpace.toJson)
+            }.toJson,
+                "operatingSystem" -> SystemStats.operatingSystemStats.toJson
+            ))
+      }
+    }
+
     /**
       * Initializes services
       */
diff --git a/src/main/scala/com/drivergrp/core/stats.scala b/src/main/scala/com/drivergrp/core/stats.scala
index cd77f7a..963e4ea 100644
--- a/src/main/scala/com/drivergrp/core/stats.scala
+++ b/src/main/scala/com/drivergrp/core/stats.scala
@@ -1,5 +1,9 @@
 package com.drivergrp.core
 
+import java.io.File
+import java.lang.management.ManagementFactory
+import java.lang.reflect.Modifier
+
 import com.drivergrp.core.logging.Logger
 import com.drivergrp.core.time.{Time, TimeRange}
 
@@ -40,4 +44,54 @@ object stats {
       log.audit(s"${keys.mkString(".")}(${interval.start.millis}-${interval.end.millis})=$valueString")
     }
   }
+
+  final case class MemoryStats(free: Long, total: Long, max: Long)
+
+  final case class GarbageCollectorStats(totalGarbageCollections: Long, garbageCollectionTime: Long)
+
+  final case class FileRootSpace(path: String, totalSpace: Long, freeSpace: Long, usableSpace: Long)
+
+  object SystemStats {
+
+    def memoryUsage: MemoryStats = {
+      val runtime = Runtime.getRuntime
+      MemoryStats(runtime.freeMemory, runtime.totalMemory, runtime.maxMemory)
+    }
+
+    def availableProcessors: Int = {
+      Runtime.getRuntime.availableProcessors()
+    }
+
+    def garbageCollectorStats: GarbageCollectorStats = {
+      import scala.collection.JavaConverters._
+
+      val (totalGarbageCollections, garbageCollectionTime) =
+        ManagementFactory.getGarbageCollectorMXBeans.asScala.foldLeft(0L -> 0L) {
+          case ((total, collectionTime), gc) =>
+            (total + math.min(0L, gc.getCollectionCount)) -> (collectionTime + math.min(0L, gc.getCollectionTime))
+        }
+
+      GarbageCollectorStats(totalGarbageCollections, garbageCollectionTime)
+    }
+
+    def fileSystemSpace: Array[FileRootSpace] = {
+      File.listRoots() map { root =>
+        FileRootSpace(root.getAbsolutePath, root.getTotalSpace, root.getFreeSpace, root.getUsableSpace)
+      }
+    }
+
+    def operatingSystemStats: Map[String, String] = {
+      val operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean
+      operatingSystemMXBean.getClass.getDeclaredMethods
+        .map(method => { method.setAccessible(true); method })
+        .filter(method => method.getName.startsWith("get") && Modifier.isPublic(method.getModifiers))
+        .map { method =>
+          try {
+            method.getName -> String.valueOf(method.invoke(operatingSystemMXBean))
+          } catch {
+            case t: Throwable => method.getName -> t.getMessage
+        }
+      } toMap
+    }
+  }
 }
-- 
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