[SPARK-29233][K8S] Add regex expression checks for executorEnv…

### What changes were proposed in this pull request?

In kubernetes, there are some naming regular expression requirements and restrictions on environment variable names, such as:

- In kubernetes version release-1.7 and earlier, the naming rules of pod environment variable names should meet the requirements of regular expressions: [[A-Za-z_] [A-Za-z0-9_]*](https://github.com/kubernetes/kubernetes/blob/release-1.7/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L169)
- In kubernetes version release-1.8 and later, the naming rules of pod environment variable names should meet the requirements of regular expressions: [[-. _ A-ZA-Z][-. _ A-ZA-Z0-9].*](https://github.com/kubernetes/kubernetes/blob/release-1.8/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L305)

However, in spark on k8s mode, spark should add restrictions on environmental variable names when creating executorEnv.

In addition, we need to use regular expressions adapted to the high version of k8s to increase the restrictions on the names of environmental variables.

Otherwise, the pod will not be created properly and the spark application will be suspended.

To solve the problem above, a regular validation to executorEnv is added and committed. 

### Why are the changes needed?

If no validation rules are added, the environment variable names that don't meet the requirements will cause the pod to not be created properly and the application will be suspended.

### Does this PR introduce any user-facing change?

No.

### How was this patch tested?

Add unit tests and manually run.

Closes #25920 from merrily01/SPARK-29233.

Authored-by: maruilei <maruilei@jd.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>

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

@@ -24,6 +24,7 @@ import org.apache.spark.SparkConf
 import org.apache.spark.deploy.k8s.Config._
 import org.apache.spark.deploy.k8s.Constants._
 import org.apache.spark.deploy.k8s.submit._
+import org.apache.spark.internal.Logging
 import org.apache.spark.internal.config.ConfigEntry
 import org.apache.spark.util.Utils
 
@@ -123,7 +124,7 @@ private[spark] class KubernetesExecutorConf(
     val appId: String,
     val executorId: String,
     val driverPod: Option[Pod])
-  extends KubernetesConf(sparkConf) {
+  extends KubernetesConf(sparkConf) with Logging {
 
   override val resourceNamePrefix: String = {
     get(KUBERNETES_EXECUTOR_POD_NAME_PREFIX).getOrElse(
@@ -148,7 +149,8 @@ private[spark] class KubernetesExecutorConf(
     executorCustomLabels ++ presetLabels
   }
 
-  override def environment: Map[String, String] = sparkConf.getExecutorEnv.toMap
+  override def environment: Map[String, String] = sparkConf.getExecutorEnv.filter(
+    p => checkExecutorEnvKey(p._1)).toMap
 
   override def annotations: Map[String, String] = {
     KubernetesUtils.parsePrefixedKeyValuePairs(sparkConf, KUBERNETES_EXECUTOR_ANNOTATION_PREFIX)
@@ -166,6 +168,20 @@ private[spark] class KubernetesExecutorConf(
     KubernetesVolumeUtils.parseVolumesWithPrefix(sparkConf, KUBERNETES_EXECUTOR_VOLUMES_PREFIX)
   }
 
+  private def checkExecutorEnvKey(key: String): Boolean = {
+    // Pattern for matching an executorEnv key, which meets certain naming rules.
+    val executorEnvRegex = "[-._a-zA-Z][-._a-zA-Z0-9]*".r
+    if (executorEnvRegex.pattern.matcher(key).matches()) {
+      true
+    } else {
+      logWarning(s"Invalid key: $key: " +
+        "a valid environment variable name must consist of alphabetic characters, " +
+        "digits, '_', '-', or '.', and must not start with a digit." +
+        s"Regex used for validation is '$executorEnvRegex')")
+      false
+    }
+  }
+
 }
 
 private[spark] object KubernetesConf {

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

@@ -44,6 +44,12 @@ class KubernetesConfSuite extends SparkFunSuite {
     "customEnvKey2" -> "customEnvValue2")
   private val DRIVER_POD = new PodBuilder().build()
   private val EXECUTOR_ID = "executor-id"
+  private val EXECUTOR_ENV_VARS = Map(
+    "spark.executorEnv.1executorEnvVars1/var1" -> "executorEnvVars1",
+    "spark.executorEnv.executorEnvVars2*var2" -> "executorEnvVars2",
+    "spark.executorEnv.executorEnvVars3_var3" -> "executorEnvVars3",
+    "spark.executorEnv.executorEnvVars4-var4" -> "executorEnvVars4",
+    "spark.executorEnv.executorEnvVars5-var5" -> "executorEnvVars5/var5")
 
   test("Resolve driver labels, annotations, secret mount paths, envs, and memory overhead") {
     val sparkConf = new SparkConf(false)
@@ -132,4 +138,22 @@ class KubernetesConfSuite extends SparkFunSuite {
     assert(conf.secretNamesToMountPaths === SECRET_NAMES_TO_MOUNT_PATHS)
     assert(conf.secretEnvNamesToKeyRefs === SECRET_ENV_VARS)
   }
+
+  test("Verify that executorEnv key conforms to the regular specification") {
+    val sparkConf = new SparkConf(false)
+    EXECUTOR_ENV_VARS.foreach { case (key, value) =>
+      sparkConf.set(key, value)
+    }
+
+    val conf = KubernetesConf.createExecutorConf(
+      sparkConf,
+      EXECUTOR_ID,
+      KubernetesTestConf.APP_ID,
+      Some(DRIVER_POD))
+    assert(conf.environment ===
+      Map(
+        "executorEnvVars3_var3" -> "executorEnvVars3",
+        "executorEnvVars4-var4" -> "executorEnvVars4",
+        "executorEnvVars5-var5" -> "executorEnvVars5/var5"))
+  }
 }