Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/19272#discussion_r146437027
--- Diff:
resource-managers/mesos/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosCredentialRenewer.scala
---
@@ -0,0 +1,169 @@
+/*
+ * 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.scheduler.cluster.mesos
+
+import java.security.PrivilegedExceptionAction
+import java.util.concurrent.{Executors, TimeUnit}
+
+import scala.collection.JavaConverters._
+import scala.util.Try
+
+import org.apache.hadoop.security.UserGroupInformation
+
+import org.apache.spark.SparkConf
+import org.apache.spark.deploy.SparkHadoopUtil
+import org.apache.spark.deploy.security.HadoopDelegationTokenManager
+import org.apache.spark.internal.Logging
+import org.apache.spark.internal.config
+import org.apache.spark.rpc.RpcEndpointRef
+import
org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages.UpdateDelegationTokens
+import org.apache.spark.util.ThreadUtils
+
+
+/**
+ * The MesosCredentialRenewer will update the Hadoop credentials for Spark
drivers accessing
+ * secured services using Kerberos authentication. It is modeled after the
YARN AMCredential
+ * renewer, and similarly will renew the Credentials when 75% of the
renewal interval has passed.
+ * The principal difference is that instead of writing the new credentials
to HDFS and
+ * incrementing the timestamp of the file, the new credentials (called
Tokens when they are
+ * serialized) are broadcast to all running executors. On the executor
side, when new Tokens are
+ * recieved they overwrite the current credentials.
+ */
+class MesosCredentialRenewer(
+ conf: SparkConf,
+ tokenManager: HadoopDelegationTokenManager,
+ nextRenewal: Long,
+ driverEndpoint: RpcEndpointRef) extends Logging {
+ private val credentialRenewerThread =
+ ThreadUtils.newDaemonSingleThreadScheduledExecutor("Credential Renewal
Thread")
+
+ @volatile private var timeOfNextRenewal = nextRenewal
+
+ private val principal = conf.get(config.PRINCIPAL).orNull
+
+ private val (secretFile, mode) = getSecretFile(conf)
+
+ private def getSecretFile(conf: SparkConf): (String, String) = {
+ val keytab = conf.get(config.KEYTAB).orNull
+ val tgt = conf.getenv("KRB5CCNAME")
+ require(keytab != null || tgt != null, "A keytab or TGT required.")
+ // if both Keytab and TGT are detected we use the Keytab.
+ val (secretFile, mode) = if (keytab != null && tgt != null) {
+ logWarning(s"Keytab and TGT were detected, using keytab, unset
$keytab to use TGT")
+ (keytab, "keytab")
+ } else {
+ val m = if (keytab != null) "keytab" else "tgt"
+ val sf = if (keytab != null) keytab else tgt
+ (sf, m)
+ }
+ logInfo(s"Logging in as $principal with mode $mode to retrieve Hadoop
delegation tokens")
+ logDebug(s"secretFile is $secretFile")
+ (secretFile, mode)
+ }
+
+ def scheduleTokenRenewal(): Unit = {
+ def scheduleRenewal(runnable: Runnable): Unit = {
+ val remainingTime = timeOfNextRenewal - System.currentTimeMillis()
+ if (remainingTime <= 0) {
+ logInfo("Credentials have expired, creating new ones now.")
+ runnable.run()
+ } else {
+ logInfo(s"Scheduling login from keytab in $remainingTime millis.")
+ credentialRenewerThread.schedule(runnable, remainingTime,
TimeUnit.MILLISECONDS)
+ }
+ }
+
+ val credentialRenewerRunnable =
+ new Runnable {
+ override def run(): Unit = {
+ try {
+ val creds = getRenewedDelegationTokens(conf)
+ broadcastDelegationTokens(creds)
+ } catch {
+ case e: Exception =>
+ // Log the error and try to write new tokens back in an hour
+ logWarning("Couldn't broadcast tokens, trying again in an
hour", e)
+ credentialRenewerThread.schedule(this, 1, TimeUnit.HOURS)
+ return
+ }
+ scheduleRenewal(this)
+ }
+ }
+ scheduleRenewal(credentialRenewerRunnable)
+ }
+
+ private def getRenewedDelegationTokens(conf: SparkConf): Array[Byte] = {
+ logInfo(s"Attempting to login with
${conf.get(config.PRINCIPAL).orNull}")
+ // Get new delegation tokens by logging in with a new UGI
+ // inspired by AMCredentialRenewer.scala:L174
+ val ugi = if (mode == "keytab") {
+ UserGroupInformation.loginUserFromKeytabAndReturnUGI(principal,
secretFile)
+ } else {
+ UserGroupInformation.getUGIFromTicketCache(secretFile, principal)
+ }
+ val tempCreds = ugi.getCredentials
+ val hadoopConf = SparkHadoopUtil.get.newConfiguration(conf)
+ var nextRenewalTime = Long.MaxValue
+ ugi.doAs(new PrivilegedExceptionAction[Void] {
+ override def run(): Void = {
+ nextRenewalTime = tokenManager.obtainDelegationTokens(hadoopConf,
tempCreds)
+ null
+ }
+ })
+
+ val currTime = System.currentTimeMillis()
+ timeOfNextRenewal = if (nextRenewalTime <= currTime) {
+ logWarning(s"Next credential renewal time ($nextRenewalTime) is
earlier than " +
+ s"current time ($currTime), which is unexpected, please check your
credential renewal " +
+ "related configurations in the target services.")
+ currTime
+ } else {
+ MesosCredentialRenewer.getNextRenewalTime(nextRenewalTime)
+ }
+ logInfo(s"Time of next renewal is $timeOfNextRenewal")
+
+ // Add the temp credentials back to the original ones.
+ UserGroupInformation.getCurrentUser.addCredentials(tempCreds)
+ SparkHadoopUtil.get.serialize(tempCreds)
+ }
+
+ private def broadcastDelegationTokens(tokens: Array[Byte]): Unit = {
+ // send token to existing executors
--- End diff --
Comment is redundant.
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