[SPARK-39023] [K8s] Add Executor Pod inter-pod anti-affinity

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala

@@ -684,6 +684,15 @@ private[spark] object Config extends Logging {
       .checkValue(value => value > 0, "Maximum number of pending pods should be a positive integer")
       .createWithDefault(Int.MaxValue)
 
+  private [spark] val KUBERNETES_EXECUTOR_POD_ANTI_AFFINITY =
+    ConfigBuilder("spark.kubernetes.executor.pod.antiAffinity.enable")
+      .doc("If enable, register executor with anti affinity. This anti affinity will help " +
+        "Kubernetes assign executors of the same Application to different nodes " +
+        "as much as possible")
+      .version("3.2.1")
+      .booleanConf
+      .createWithDefault(false)
+
   val KUBERNETES_DRIVER_LABEL_PREFIX = "spark.kubernetes.driver.label."
   val KUBERNETES_DRIVER_ANNOTATION_PREFIX = "spark.kubernetes.driver.annotation."
   val KUBERNETES_DRIVER_SERVICE_ANNOTATION_PREFIX = "spark.kubernetes.driver.service.annotation."

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/features/AntiAffinityFeatureStep.scala

@@ -0,0 +1,61 @@
+/*
+ * 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.deploy.k8s.features
+
+import io.fabric8.kubernetes.api.model.PodBuilder
+
+import org.apache.spark.deploy.k8s.{KubernetesExecutorConf, SparkPod}
+import org.apache.spark.deploy.k8s.Config.KUBERNETES_EXECUTOR_POD_ANTI_AFFINITY
+import org.apache.spark.deploy.k8s.Constants.SPARK_APP_ID_LABEL
+import org.apache.spark.internal.Logging
+
+class AntiAffinityFeatureStep(kubernetesConf: KubernetesExecutorConf)
+  extends KubernetesFeatureConfigStep with Logging {
+
+  private val enableExecutorPodAntiAffinity =
+    kubernetesConf.get(KUBERNETES_EXECUTOR_POD_ANTI_AFFINITY)
+
+  override def configurePod(pod: SparkPod): SparkPod = {
+    if (enableExecutorPodAntiAffinity) {
+      val podWithAntiAffinity = new PodBuilder(pod.pod)
+        .editOrNewSpec()
+          .editOrNewAffinity()
+            .editOrNewPodAntiAffinity()
+              .addNewPreferredDuringSchedulingIgnoredDuringExecution()
+                .withWeight(100)
+                .editOrNewPodAffinityTerm()
+                  .withTopologyKey("kubernetes.io/hostname")
+                  .editOrNewLabelSelector()
+                    .addNewMatchExpression()
+                    .withKey(SPARK_APP_ID_LABEL)
+                    .withOperator("In")
+                    .withValues(kubernetesConf.appId)
+                    .endMatchExpression()
+                  .endLabelSelector()
+                .endPodAffinityTerm()
+              .endPreferredDuringSchedulingIgnoredDuringExecution()
+            .endPodAntiAffinity()
+          .endAffinity()
+        .endSpec()
+        .build()
+      SparkPod(podWithAntiAffinity, pod.container)
+    } else {
+      pod
+    }
+  }
+}
+

resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/KubernetesExecutorBuilder.scala

@@ -71,7 +71,8 @@ private[spark] class KubernetesExecutorBuilder {
       new MountSecretsFeatureStep(conf),
       new EnvSecretsFeatureStep(conf),
       new MountVolumesFeatureStep(conf),
-      new LocalDirsFeatureStep(conf)) ++ userFeatures
+      new LocalDirsFeatureStep(conf),
+      new AntiAffinityFeatureStep(conf)) ++ userFeatures
 
     val spec = KubernetesExecutorSpec(
       initialPod,

resource-managers/kubernetes/core/src/test/scala/org/apache/spark/deploy/k8s/features/AntiAffinityFeatureStepSuite.scala

@@ -0,0 +1,58 @@
+/*
+ * 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.deploy.k8s.features
+
+import org.apache.spark.{SparkConf, SparkFunSuite}
+import org.apache.spark.deploy.k8s.{KubernetesTestConf, SparkPod}
+import org.apache.spark.deploy.k8s.Constants.SPARK_APP_ID_LABEL
+
+class AntiAffinityFeatureStepSuite extends SparkFunSuite {
+
+  test("enable executor pod antiAffinity") {
+    val conf = new SparkConf()
+      .set("spark.kubernetes.executor.pod.antiAffinity.enable", "true")
+    val executorConf = KubernetesTestConf.createExecutorConf(conf)
+    val sparkPod =
+      new AntiAffinityFeatureStep(executorConf).configurePod(SparkPod.initialPod())
+
+    val podAntiAffinity = sparkPod.pod.getSpec.getAffinity.getPodAntiAffinity
+    assert(podAntiAffinity != null)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution != null)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.size() == 1)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0).getPodAffinityTerm != null)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0)
+      .getPodAffinityTerm.getLabelSelector != null)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0)
+      .getPodAffinityTerm.getLabelSelector.getMatchExpressions != null)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0)
+      .getPodAffinityTerm.getLabelSelector.getMatchExpressions.size() == 1)
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0)
+      .getPodAffinityTerm.getLabelSelector.getMatchExpressions.get(0)
+      .getKey.equals(SPARK_APP_ID_LABEL))
+    assert(podAntiAffinity
+      .getPreferredDuringSchedulingIgnoredDuringExecution.get(0)
+      .getPodAffinityTerm.getLabelSelector.getMatchExpressions.get(0)
+      .getValues.get(0).equals(KubernetesTestConf.APP_ID))
+  }
+}