[SPARK-20059][YARN] Use the correct classloader for HBaseCredentialProvider

## What changes were proposed in this pull request?

Currently we use system classloader to find HBase jars, if it is specified by `--jars`, then it will be failed with ClassNotFound issue. So here changing to use child classloader.

Also putting added jars and main jar into classpath of submitted application in yarn cluster mode, otherwise HBase jars specified with `--jars` will never be honored in cluster mode, and fetching tokens in client side will always be failed.

## How was this patch tested?

Unit test and local verification.

Author: jerryshao <sshao@hortonworks.com>

Closes #17388 from jerryshao/SPARK-20059.

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -485,12 +485,17 @@ object SparkSubmit extends CommandLineUtils {
 
     // In client mode, launch the application main class directly
     // In addition, add the main application jar and any added jars (if any) to the classpath
-    if (deployMode == CLIENT) {
+    // Also add the main application jar and any added jars to classpath in case YARN client
+    // requires these jars.
+    if (deployMode == CLIENT || isYarnCluster) {
       childMainClass = args.mainClass
       if (isUserJar(args.primaryResource)) {
         childClasspath += args.primaryResource
       }
       if (args.jars != null) { childClasspath ++= args.jars.split(",") }
+    }
+
+    if (deployMode == CLIENT) {
       if (args.childArgs != null) { childArgs ++= args.childArgs }
     }
 

core/src/test/scala/org/apache/spark/deploy/SparkSubmitSuite.scala

@@ -213,7 +213,12 @@ class SparkSubmitSuite
     childArgsStr should include ("--arg arg1 --arg arg2")
     childArgsStr should include regex ("--jar .*thejar.jar")
     mainClass should be ("org.apache.spark.deploy.yarn.Client")
-    classpath should have length (0)
+
+    // In yarn cluster mode, also adding jars to classpath
+    classpath(0) should endWith ("thejar.jar")
+    classpath(1) should endWith ("one.jar")
+    classpath(2) should endWith ("two.jar")
+    classpath(3) should endWith ("three.jar")
 
     sysProps("spark.executor.memory") should be ("5g")
     sysProps("spark.driver.memory") should be ("4g")

resource-managers/yarn/src/main/scala/org/apache/spark/deploy/yarn/security/HBaseCredentialProvider.scala

@@ -26,6 +26,7 @@ import org.apache.hadoop.security.token.{Token, TokenIdentifier}
 
 import org.apache.spark.SparkConf
 import org.apache.spark.internal.Logging
+import org.apache.spark.util.Utils
 
 private[security] class HBaseCredentialProvider extends ServiceCredentialProvider with Logging {
 
@@ -36,7 +37,7 @@ private[security] class HBaseCredentialProvider extends ServiceCredentialProvide
       sparkConf: SparkConf,
       creds: Credentials): Option[Long] = {
     try {
-      val mirror = universe.runtimeMirror(getClass.getClassLoader)
+      val mirror = universe.runtimeMirror(Utils.getContextOrSparkClassLoader)
       val obtainToken = mirror.classLoader.
         loadClass("org.apache.hadoop.hbase.security.token.TokenUtil").
         getMethod("obtainToken", classOf[Configuration])
@@ -60,7 +61,7 @@ private[security] class HBaseCredentialProvider extends ServiceCredentialProvide
 
   private def hbaseConf(conf: Configuration): Configuration = {
     try {
-      val mirror = universe.runtimeMirror(getClass.getClassLoader)
+      val mirror = universe.runtimeMirror(Utils.getContextOrSparkClassLoader)
       val confCreate = mirror.classLoader.
         loadClass("org.apache.hadoop.hbase.HBaseConfiguration").
         getMethod("create", classOf[Configuration])