Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/19272#discussion_r150053337
--- Diff:
resource-managers/mesos/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosHadoopDelegationTokenManager.scala
---
@@ -0,0 +1,180 @@
+/*
+ * 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.{ScheduledExecutorService, TimeUnit}
+
+import org.apache.hadoop.conf.Configuration
+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.{config, Logging}
+import org.apache.spark.rpc.RpcEndpointRef
+import
org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages.UpdateDelegationTokens
+import org.apache.spark.util.ThreadUtils
+
+
+/**
+ * The MesosHadoopDelegationTokenManager fetches and updates Hadoop
delegation tokens on the behalf
+ * of the MesosCoarseGrainedSchedulerBackend. It is modeled after the YARN
AMCredentialRenewer,
+ * 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
+ * received they overwrite the current credentials.
+ */
+private[spark] class MesosHadoopDelegationTokenManager(
+ conf: SparkConf, hadoopConfig: Configuration,
+ driverEndpoint: RpcEndpointRef)
+ extends Logging {
+
+ private val credentialRenewerThread: ScheduledExecutorService =
+ ThreadUtils.newDaemonSingleThreadScheduledExecutor("Credential Renewal
Thread")
+
+ private val tokenManager: HadoopDelegationTokenManager =
+ new HadoopDelegationTokenManager(conf, hadoopConfig)
+
+ private val principal: String = conf.get(config.PRINCIPAL).orNull
+
+ private val (secretFile: String, mode: String) = getSecretFile(conf)
+
+ private var (tokens: Array[Byte], timeOfNextRenewal: Long) = {
+ try {
+ val creds = UserGroupInformation.getCurrentUser.getCredentials
+ val hadoopConf = SparkHadoopUtil.get.newConfiguration(conf)
+ val rt = tokenManager.obtainDelegationTokens(hadoopConf, creds)
+ logInfo(s"Initialized tokens:
${SparkHadoopUtil.get.dumpTokens(creds)}")
+ (SparkHadoopUtil.get.serialize(creds), rt)
+ } catch {
+ case e: Exception =>
+ throw new IllegalStateException("Failed to initialize Hadoop
delegation tokens\n" +
+ s"\tPricipal: $principal\n\tmode: $mode\n\tsecret file
$secretFile\n\tException: $e")
+ }
+ }
+
+ scheduleTokenRenewal()
+
+ 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.")
--- End diff --
Is that really the case? `KRB5CCNAME` is not a required env variable. It
has a default value, and the `UGI` class will use the credentials from the
default location if they're available (and reloading the cache periodically).
So I think you don't really need this, but just to track whether there's a
principal and keytab. And you don't need to call `getUGIFromTicketCache` later
on since I'm pretty sure UGI takes care of that for you.
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