From 4733a2958a7b68ce311442f9b498d6b64dbee6a5 Mon Sep 17 00:00:00 2001
From: nitrajen <58795594+nitrajen@users.noreply.github.com>
Date: Mon, 23 Mar 2026 16:07:57 -0500
Subject: [PATCH 1/2] [SPARK-55330][K8S] Make
 spark.kubernetes.legacy.useReadWriteOnceAccessMode a public config

---
 .../org/apache/spark/deploy/k8s/Config.scala  |  8 ++--
 .../MountVolumesFeatureStepSuite.scala        | 46 +++++++++++++++++++
 2 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala b/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala
index 6f1130853c5a1..949865bf94f2b 100644
--- a/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala
+++ b/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/deploy/k8s/Config.scala
@@ -65,10 +65,10 @@ private[spark] object Config extends Logging {
 
   val KUBERNETES_USE_LEGACY_PVC_ACCESS_MODE =
     ConfigBuilder("spark.kubernetes.legacy.useReadWriteOnceAccessMode")
-      .internal()
-      .doc("If true, use ReadWriteOnce instead of ReadWriteOncePod as persistence volume " +
-        "access mode.")
-      .version("3.4.3")
+      .doc("If true, use ReadWriteOnce instead of ReadWriteOncePod as the access mode for " +
+        "dynamically created PersistentVolumeClaims. Set this to true when using a storage " +
+        "class or Kubernetes cluster that does not support the ReadWriteOncePod access mode.")
+      .version("4.2.0")
       .booleanConf
       .createWithDefault(false)
 
diff --git a/resource-managers/kubernetes/core/src/test/scala/org/apache/spark/deploy/k8s/features/MountVolumesFeatureStepSuite.scala b/resource-managers/kubernetes/core/src/test/scala/org/apache/spark/deploy/k8s/features/MountVolumesFeatureStepSuite.scala
index 293773ddb9ec5..4afb4ba7798f0 100644
--- a/resource-managers/kubernetes/core/src/test/scala/org/apache/spark/deploy/k8s/features/MountVolumesFeatureStepSuite.scala
+++ b/resource-managers/kubernetes/core/src/test/scala/org/apache/spark/deploy/k8s/features/MountVolumesFeatureStepSuite.scala
@@ -18,8 +18,12 @@ package org.apache.spark.deploy.k8s.features
 
 import scala.jdk.CollectionConverters._
 
+import io.fabric8.kubernetes.api.model.PersistentVolumeClaim
+
+import org.apache.spark.SparkConf
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.deploy.k8s._
+import org.apache.spark.deploy.k8s.Config.KUBERNETES_USE_LEGACY_PVC_ACCESS_MODE
 
 class MountVolumesFeatureStepSuite extends SparkFunSuite {
   test("Mounts hostPath volumes") {
@@ -540,6 +544,48 @@ class MountVolumesFeatureStepSuite extends SparkFunSuite {
     assert(executorPVC.getClaimName.endsWith("-exec-1-pvc-0"))
   }
 
+  test("SPARK-55330: OnDemand PVC uses ReadWriteOncePod access mode by default") {
+    val volumeConf = KubernetesVolumeSpec(
+      "testVolume",
+      "/tmp",
+      "",
+      "",
+      false,
+      KubernetesPVCVolumeConf(MountVolumesFeatureStep.PVC_ON_DEMAND,
+        storageClass = Some("fast"),
+        size = Some("1Gi"))
+    )
+    val executorConf = KubernetesTestConf.createExecutorConf(volumes = Seq(volumeConf))
+    val step = new MountVolumesFeatureStep(executorConf)
+    step.configurePod(SparkPod.initialPod())
+    val pvcs = step.getAdditionalKubernetesResources().map(_.asInstanceOf[PersistentVolumeClaim])
+    assert(pvcs.size === 1)
+    assert(pvcs.head.getSpec.getAccessModes.asScala === Seq("ReadWriteOncePod"))
+  }
+
+  test("SPARK-55330: OnDemand PVC uses ReadWriteOnce when legacy access mode is enabled") {
+    val volumeConf = KubernetesVolumeSpec(
+      "testVolume",
+      "/tmp",
+      "",
+      "",
+      false,
+      KubernetesPVCVolumeConf(MountVolumesFeatureStep.PVC_ON_DEMAND,
+        storageClass = Some("fast"),
+        size = Some("1Gi"))
+    )
+    val sparkConf = new SparkConf(false)
+      .set(KUBERNETES_USE_LEGACY_PVC_ACCESS_MODE, true)
+    val executorConf = KubernetesTestConf.createExecutorConf(
+      sparkConf = sparkConf,
+      volumes = Seq(volumeConf))
+    val step = new MountVolumesFeatureStep(executorConf)
+    step.configurePod(SparkPod.initialPod())
+    val pvcs = step.getAdditionalKubernetesResources().map(_.asInstanceOf[PersistentVolumeClaim])
+    assert(pvcs.size === 1)
+    assert(pvcs.head.getSpec.getAccessModes.asScala === Seq("ReadWriteOnce"))
+  }
+
   test("SPARK-49833: Mount multiple volumes to executor with annotations") {
     val pvcVolumeConf1 = KubernetesVolumeSpec(
       "checkpointVolume1",

From 194378bd7a154da2290ed4798498808b1acd0c45 Mon Sep 17 00:00:00 2001
From: nitrajen <58795594+nitrajen@users.noreply.github.com>
Date: Mon, 23 Mar 2026 16:28:35 -0500
Subject: [PATCH 2/2] trigger CI