Add the endpoint /api/metrics for Prometheus.

core/src/main/scala/com/criteo/cuttle/App.scala

@@ -13,8 +13,9 @@ import scala.concurrent.duration._
 import scala.concurrent.ExecutionContext.Implicits.global
 
 import authentication._
-import logging._
 import ExecutionStatus._
+import Metrics.{Prometheus, Gauge}
+import utils.getJVMUptime
 
 private[cuttle] object App {
   private implicit val S = fs2.Strategy.fromExecutionContext(global)
@@ -136,10 +137,13 @@ private[cuttle] object App {
     }
 }
 
-private[cuttle] case class App[S <: Scheduling](project: CuttleProject[S], executor: Executor[S], xa: XA, logger: Logger) {
+private[cuttle] case class App[S <: Scheduling](project: CuttleProject[S], executor: Executor[S], xa: XA,
+                                                logger: Logger) {
   import App._
   import project.{scheduler, workflow}
 
+  private def allJobs = workflow.vertices.map(_.id)
+
   val publicApi: PartialService = {
 
     case GET at url"/api/status" => {
@@ -157,40 +161,42 @@ private[cuttle] case class App[S <: Scheduling](project: CuttleProject[S], execu
     case GET at url"/api/statistics?events=$events&jobs=$jobs" =>
       val filteredJobs = Try(jobs.split(",").toSeq.filter(_.nonEmpty)).toOption
         .filter(_.nonEmpty)
-        .getOrElse(workflow.vertices.map(_.id))
+        .getOrElse(allJobs)
         .toSet
-      def getStats() =
-        Some(
-          (executor.runningExecutionsSizes(filteredJobs),
-           executor.pausedExecutionsSize(filteredJobs),
-           executor.failingExecutionsSize(filteredJobs)))
-      def asJson(x: ((Int, Int), Int, Int)) = x match {
-        case ((running, waiting), paused, failing) =>
-          Json.obj(
-            "running" -> running.asJson,
-            "waiting" -> waiting.asJson,
-            "paused" -> paused.asJson,
-            "failing" -> failing.asJson,
-            "scheduler" -> scheduler.getStats(filteredJobs)
-          )
+
+      def getStats() = Try(
+        executor.getStats(filteredJobs) -> scheduler.getStats(filteredJobs)
+      ).toOption
+
+      def asJson(x: (Json, Json)) = x match {
+        case (executorStats, schedulerStats) =>
+          executorStats.deepMerge(Json.obj(
+            "scheduler" -> schedulerStats
+          ))
       }
+
       events match {
         case "true" | "yes" =>
           sse(getStats _, asJson)
         case _ =>
-          Ok(asJson(getStats().get))
+          getStats().map(stat => Ok(asJson(stat))).getOrElse(InternalServerError)
       }
 
     case GET at url"/api/statistics/$jobName" =>
       Ok(executor.jobStatsForLastThirtyDays(jobName).asJson)
 
+    case GET at "/metrics" =>
+      val metrics = executor.getMetrics(allJobs) ++ scheduler.getMetrics(allJobs) :+
+        Gauge("jvm_uptime_seconds", getJVMUptime)
+      Ok(Prometheus.format(metrics))
+
     case GET at url"/api/executions/status/$kind?limit=$l&offset=$o&events=$events&sort=$sort&order=$a&jobs=$jobs" =>
       val limit = Try(l.toInt).toOption.getOrElse(25)
       val offset = Try(o.toInt).toOption.getOrElse(0)
       val asc = (a.toLowerCase == "asc")
       val filteredJobs = Try(jobs.split(",").toSeq.filter(_.nonEmpty)).toOption
         .filter(_.nonEmpty)
-        .getOrElse(workflow.vertices.map(_.id))
+        .getOrElse(allJobs)
         .toSet
       def getExecutions() = kind match {
         case "started" =>

core/src/main/scala/com/criteo/cuttle/Cuttle.scala

@@ -2,7 +2,6 @@ package com.criteo.cuttle
 
 import lol.http._
 import scala.concurrent.ExecutionContext.Implicits.global
-import com.criteo.cuttle.logging.Logger
 
 class CuttleProject[S <: Scheduling] private[cuttle] (
   val name: String,
@@ -19,7 +18,7 @@ class CuttleProject[S <: Scheduling] private[cuttle] (
     httpPort: Int = 8888,
     databaseConfig: DatabaseConfig = DatabaseConfig.fromEnv,
     retryStrategy: RetryStrategy = RetryStrategy.ExponentialBackoffRetryStrategy
-  ) = {
+  ): Unit = {
     val xa = Database.connect(databaseConfig)
     val executor = new Executor[S](platforms, xa, logger = logger)(retryStrategy)
 
@@ -37,8 +36,8 @@ object CuttleProject {
                              version: String = "",
                              description: String = "",
                              env: (String, Boolean) = ("", false),
-                             authenticator: Authenticator = GuestAuth)
-                             (workflow: Workflow[S])(implicit scheduler: Scheduler[S], logger: Logger): CuttleProject[S] =
+                             authenticator: Authenticator = GuestAuth)(
+    workflow: Workflow[S])(implicit scheduler: Scheduler[S], logger: Logger): CuttleProject[S] =
     new CuttleProject(name, version, description, env, workflow, scheduler, authenticator, logger)
 
   private[CuttleProject] def defaultPlatforms: Seq[ExecutionPlatform] = {

core/src/main/scala/com/criteo/cuttle/Executor.scala

@@ -13,14 +13,15 @@ import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.stm._
 import scala.concurrent.stm.Txn.ExternalDecider
 import scala.concurrent.duration._
-import scala.reflect.{classTag, ClassTag}
+import scala.reflect.{ClassTag, classTag}
 import lol.http.PartialService
 import doobie.imports._
 import cats.implicits._
 import io.circe._
-
+import io.circe.syntax._
 import authentication._
-import logging._
+
+import Metrics._
 
 trait RetryStrategy {
   def apply[S <: Scheduling](job: Job[S], context: S#Context, previouslyFailing: List[String]): Duration
@@ -207,7 +208,7 @@ private[cuttle] object ExecutionPlatform {
 class Executor[S <: Scheduling] private[cuttle] (
   val platforms: Seq[ExecutionPlatform],
   xa: XA,
-  logger: Logger)(implicit retryStrategy: RetryStrategy) {
+  logger: Logger)(implicit retryStrategy: RetryStrategy) extends MetricProvider {
 
   val queries = new Queries {
     val appLogger = logger
@@ -274,9 +275,7 @@ class Executor[S <: Scheduling] private[cuttle] (
     flagWaitingExecutions(runningState.single.keys.toSeq)
 
   private[cuttle] def runningExecutionsSizeTotal(filteredJobs: Set[String]): Int =
-    runningState.single.keys
-      .filter(e => filteredJobs.contains(e.job.id))
-      .size
+    runningState.single.keys.count(e => filteredJobs.contains(e.job.id))
 
   private[cuttle] def runningExecutionsSizes(filteredJobs: Set[String]): (Int, Int) = {
     val statuses =
@@ -378,6 +377,39 @@ class Executor[S <: Scheduling] private[cuttle] (
                                          limit: Int): Seq[ExecutionLog] =
     queries.getExecutionLog(queryContexts, jobs, sort, asc, offset, limit).transact(xa).unsafePerformIO
 
+  /**
+    * Atomically get executor stats.
+    * @param jobs the list of jobs ids
+    * @return how much ((running, waiting), paused, failing) jobs are in concrete states
+    * */
+  private def getStateAtomic(jobs: Set[String]) = atomic { implicit txn =>
+    (runningExecutionsSizes(jobs), pausedExecutionsSize(jobs), failingExecutionsSize(jobs))
+  }
+
+  private[cuttle] def getStats(jobs: Set[String]): Json = {
+    val ((running, waiting), paused, failing) = getStateAtomic(jobs)
+    // DB state call
+    val finished = archivedExecutionsSize(jobs)
+    Map(
+      "running" -> running,
+      "waiting" -> waiting,
+      "paused" -> paused,
+      "failing" -> failing,
+      "finished" -> finished
+    ).asJson
+  }
+
+  override def getMetrics(jobs: Set[String]): Seq[Metric] = {
+    val ((running, waiting), paused, failing) = getStateAtomic(jobs)
+
+    Seq(
+      Gauge("scheduler_stat_count", running, Seq("type" -> "running")),
+      Gauge("scheduler_stat_count", waiting, Seq("type" -> "waiting")),
+      Gauge("scheduler_stat_count", paused, Seq("type" -> "paused")),
+      Gauge("scheduler_stat_count", failing, Seq("type" -> "failing"))
+    )
+  }
+
   private[cuttle] def pausedJobs: Seq[String] =
     pausedState.single.keys.toSeq
 
@@ -391,9 +423,7 @@ class Executor[S <: Scheduling] private[cuttle] (
   private[cuttle] def getExecution(queryContexts: Fragment, executionId: String): Option[ExecutionLog] =
     atomic { implicit tx =>
       val predicate = (e: Execution[S]) => e.id == executionId
-      pausedState.values
-        .map(_.keys)
-        .flatten
+      pausedState.values.flatMap(_.keys)
         .find(predicate)
         .map(_.toExecutionLog(ExecutionPaused))
         .orElse(throttledState.keys

core/src/main/scala/com/criteo/cuttle/Logging.scala → core/src/main/scala/com/criteo/cuttle/Logger.scala

@@ -1,4 +1,4 @@
-package com.criteo.cuttle.logging
+package com.criteo.cuttle
 
 trait Logger {
   def debug(message: => String): Unit

core/src/main/scala/com/criteo/cuttle/Metrics.scala

@@ -0,0 +1,27 @@
+package com.criteo.cuttle
+
+object Metrics {
+  sealed trait Metric {
+    def toString: String
+  }
+
+  case class Gauge(name: String, value: Long, tags: Seq[(String, String)] = Seq.empty) extends Metric
+
+  trait MetricProvider {
+    def getMetrics(jobs: Set[String]): Seq[Metric]
+  }
+
+  private[cuttle] object Prometheus {
+    def format(metrics: Seq[Metric]): String = {
+      val prometheusMetrics = metrics.map {
+        case Gauge(name, value, tags) =>
+          s"$name${
+            if (tags.nonEmpty) s" {${tags.map(tag => s"""${tag._1}="${tag._2}"""").mkString(", ")}}"
+            else ""
+          } $value"
+      }
+
+      s"${prometheusMetrics.mkString("\n")}\n"
+    }
+  }
+}

core/src/main/scala/com/criteo/cuttle/Scheduling.scala

@@ -5,16 +5,17 @@ import io.circe.Json
 import doobie.imports._
 import java.util.Comparator
 
-import logging._
 import authentication._
+import Metrics.MetricProvider
 
-trait Scheduler[S <: Scheduling] {
+trait Scheduler[S <: Scheduling] extends MetricProvider {
   def start(workflow: Workflow[S], executor: Executor[S], xa: XA, logger: Logger): Unit
   private[cuttle] def publicRoutes(workflow: Workflow[S], executor: Executor[S], xa: XA): PartialService =
     PartialFunction.empty
   private[cuttle] def privateRoutes(workflow: Workflow[S], executor: Executor[S], xa: XA): AuthenticatedService =
     PartialFunction.empty
   val allContexts: Fragment
+
   def getStats(jobs: Set[String]): Json
 }
 

core/src/main/scala/com/criteo/cuttle/Utils.scala

@@ -2,6 +2,7 @@ package com.criteo.cuttle
 
 import java.util.UUID
 import java.util.concurrent.{Executors, ThreadFactory, TimeUnit}
+import java.lang.management.ManagementFactory
 
 import scala.concurrent.duration.Duration
 import scala.concurrent.{ExecutionContext, Future, Promise}
@@ -55,4 +56,6 @@ package object utils {
       case e => service(e)
     }
   }
+
+  private[cuttle] def getJVMUptime = ManagementFactory.getRuntimeMXBean.getUptime / 1000
 }

core/src/main/scala/com/criteo/cuttle/package.scala

@@ -3,7 +3,6 @@ package com.criteo
 import scala.concurrent._
 import doobie.imports._
 import cats.free._
-import cuttle.logging.Logger
 
 package cuttle {
   sealed trait Completed

timeseries/src/main/scala/com/criteo/cuttle/timeseries/TimeSeriesScheduler.scala

@@ -2,7 +2,6 @@ package com.criteo.cuttle.timeseries
 
 import Internal._
 import com.criteo.cuttle._
-import com.criteo.cuttle.logging._
 
 import scala.concurrent._
 import scala.concurrent.duration.{Duration => ScalaDuration}
@@ -22,6 +21,7 @@ import java.time.temporal.{ChronoUnit, TemporalAdjusters}
 import com.criteo.cuttle.timeseries.TimeSeriesGrid.{Daily, Hourly, Monthly}
 import intervals.{Bound, Interval, IntervalMap}
 import Bound.{Bottom, Finite, Top}
+import Metrics._
 
 sealed trait TimeSeriesGrid {
   def next(t: Instant): Instant
@@ -434,15 +434,56 @@ case class TimeSeriesScheduler(logger: Logger) extends Scheduler[TimeSeries] wit
     }
   }
 
-  override def getStats(jobs: Set[String]) = {
+  private def getRunningBackfillsSize(jobs: Set[String]) = {
     val runningBackfills = state match {
       case (_, backfills) =>
         backfills.filter(
           bf =>
             bf.status == "RUNNING" &&
               bf.jobs.map(_.id).intersect(jobs).nonEmpty)
     }
-    Map("backfills" -> runningBackfills.size).asJson
+
+    runningBackfills.size
+  }
+
+  /**
+    * We compute the last instant when job was in a valid state
+    * @param jobs set of jobs to process
+    * @return Iterable of job to to last instant when job was in a valid state.
+    *         Iterable is empty when job doesn't contain any "DONE" interval.
+    */
+  private def getTimeOfLastSuccess(jobs: Set[String]) = {
+    _state.single().collect {
+      case (job, intervals) if jobs.contains(job.id) =>
+        val intervalList = intervals.toList
+        val lastValidInterval = intervalList.takeWhile {
+          case (_, Running(_)) => false
+          case (_, Todo(None)) => false
+          case _ => true
+        }.lastOption
+
+        lastValidInterval.map {
+          case (interval, _) => job -> (interval.hi match {
+            case Finite(instant) => instant
+            case _ => Instant.MAX
+          })
+        }
+    }.flatten
+  }
+
+  override def getMetrics(jobs: Set[String]): Seq[Metric] = {
+    val timeOfLastSuccessMetrics = getTimeOfLastSuccess(jobs).map {
+      case (job, instant) =>
+        Gauge("scheduler_last_success_epoch_seconds", Instant.now().getEpochSecond - instant.getEpochSecond,
+          Seq("job_id" -> job.id, "job_name" -> job.name))
+    }
+
+    Seq(Gauge("scheduler_stat_count", getRunningBackfillsSize(jobs), Seq("type" -> "backfills"))) ++
+      timeOfLastSuccessMetrics
+  }
+
+  override def getStats(jobs: Set[String]): Json = {
+    Map("backfills" -> getRunningBackfillsSize(jobs)).asJson
   }
 }