[SPARK-29064][CORE] Add PrometheusResource to export Executor metrics

core/src/main/scala/org/apache/spark/internal/config/UI.scala

@@ -81,6 +81,12 @@ private[spark] object UI {
     .booleanConf
     .createWithDefault(true)
 
+  val UI_PROMETHEUS_ENABLED = ConfigBuilder("spark.ui.prometheus.enabled")
+    .doc("Expose executor metrics at /metrics/executors/prometheus. " +
+      "For master/worker/driver metrics, you need to configure `conf/metrics.properties`.")
+    .booleanConf
+    .createWithDefault(false)
+
   val UI_X_XSS_PROTECTION = ConfigBuilder("spark.ui.xXssProtection")
     .doc("Value for HTTP X-XSS-Protection response header")
     .stringConf

core/src/main/scala/org/apache/spark/status/api/v1/PrometheusResource.scala

@@ -0,0 +1,110 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.status.api.v1
+
+import javax.ws.rs._
+import javax.ws.rs.core.MediaType
+
+import org.eclipse.jetty.servlet.{ServletContextHandler, ServletHolder}
+import org.glassfish.jersey.server.ServerProperties
+import org.glassfish.jersey.servlet.ServletContainer
+
+import org.apache.spark.ui.SparkUI
+
+/**
+ * This aims to expose Executor metrics like REST API which is documented in
+ *
+ *    https://spark.apache.org/docs/3.0.0/monitoring.html#executor-metrics
+ *
+ * Note that this is based on ExecutorSummary which is different from ExecutorSource.
+ */
+@Path("/executors")
+private[v1] class PrometheusResource extends ApiRequestContext {
+  @GET
+  @Path("prometheus")
+  @Produces(Array(MediaType.TEXT_PLAIN))
+  def executors(): String = {
+    val sb = new StringBuilder
+    val store = uiRoot.asInstanceOf[SparkUI].store
+    val appId = store.applicationInfo.id.replaceAll("[^a-zA-Z0-9]", "_")
+    store.executorList(true).foreach { executor =>
+      val prefix = s"metrics_${appId}_${executor.id}_executor_"
+      sb.append(s"${prefix}rddBlocks_Count ${executor.rddBlocks}\n")
+      sb.append(s"${prefix}memoryUsed_Count ${executor.memoryUsed}\n")
+      sb.append(s"${prefix}diskUsed_Count ${executor.diskUsed}\n")
+      sb.append(s"${prefix}totalCores_Count ${executor.totalCores}\n")
+      sb.append(s"${prefix}maxTasks_Count ${executor.maxTasks}\n")
+      sb.append(s"${prefix}activeTasks_Count ${executor.activeTasks}\n")
+      sb.append(s"${prefix}failedTasks_Count ${executor.failedTasks}\n")
+      sb.append(s"${prefix}completedTasks_Count ${executor.completedTasks}\n")
+      sb.append(s"${prefix}totalTasks_Count ${executor.totalTasks}\n")
+      sb.append(s"${prefix}totalDuration_Value ${executor.totalDuration}\n")
+      sb.append(s"${prefix}totalGCTime_Value ${executor.totalGCTime}\n")
+      sb.append(s"${prefix}totalInputBytes_Count ${executor.totalInputBytes}\n")
+      sb.append(s"${prefix}totalShuffleRead_Count ${executor.totalShuffleRead}\n")
+      sb.append(s"${prefix}totalShuffleWrite_Count ${executor.totalShuffleWrite}\n")
+      sb.append(s"${prefix}maxMemory_Count ${executor.maxMemory}\n")
+      executor.executorLogs.foreach { case (k, v) => }
+      executor.memoryMetrics.foreach { m =>
+        sb.append(s"${prefix}usedOnHeapStorageMemory_Count ${m.usedOnHeapStorageMemory}\n")
+        sb.append(s"${prefix}usedOffHeapStorageMemory_Count ${m.usedOffHeapStorageMemory}\n")
+        sb.append(s"${prefix}totalOnHeapStorageMemory_Count ${m.totalOnHeapStorageMemory}\n")
+        sb.append(s"${prefix}totalOffHeapStorageMemory_Count ${m.totalOffHeapStorageMemory}\n")
+      }
+      executor.peakMemoryMetrics.foreach { m =>
+        val names = Array(
+          "JVMHeapMemory",
+          "JVMOffHeapMemory",
+          "OnHeapExecutionMemory",
+          "OffHeapExecutionMemory",
+          "OnHeapStorageMemory",
+          "OffHeapStorageMemory",
+          "OnHeapUnifiedMemory",
+          "OffHeapUnifiedMemory",
+          "DirectPoolMemory",
+          "MappedPoolMemory",
+          "ProcessTreeJVMVMemory",
+          "ProcessTreeJVMRSSMemory",
+          "ProcessTreePythonVMemory",
+          "ProcessTreePythonRSSMemory",
+          "ProcessTreeOtherVMemory",
+          "ProcessTreeOtherRSSMemory",
+          "MinorGCCount",
+          "MinorGCTime",
+          "MajorGCCount",
+          "MajorGCTime"
+        )
+        names.foreach { name =>
+          sb.append(s"$prefix${name}_Count ${m.getMetricValue(name)}\n")
+        }
+      }
+    }
+    sb.toString
+  }
+}
+
+private[spark] object PrometheusResource {
+  def getServletHandler(uiRoot: UIRoot): ServletContextHandler = {
+    val jerseyContext = new ServletContextHandler(ServletContextHandler.NO_SESSIONS)
+    jerseyContext.setContextPath("/metrics")
+    val holder: ServletHolder = new ServletHolder(classOf[ServletContainer])
+    holder.setInitParameter(ServerProperties.PROVIDER_PACKAGES, "org.apache.spark.status.api.v1")
+    UIRootFromServletContext.setUiRoot(jerseyContext, uiRoot)
+    jerseyContext.addServlet(holder, "/*")
+    jerseyContext
+  }
+}

core/src/main/scala/org/apache/spark/ui/SparkUI.scala

@@ -66,6 +66,9 @@ private[spark] class SparkUI private (
     addStaticHandler(SparkUI.STATIC_RESOURCE_DIR)
     attachHandler(createRedirectHandler("/", "/jobs/", basePath = basePath))
     attachHandler(ApiRootResource.getServletHandler(this))
+    if (sc.map(_.conf.get(UI_PROMETHEUS_ENABLED)).getOrElse(false)) {
+      attachHandler(PrometheusResource.getServletHandler(this))
+    }
 
     // These should be POST only, but, the YARN AM proxy won't proxy POSTs
     attachHandler(createRedirectHandler(