[SPARK-16901] Hive settings in hive-site.xml may be overridden by Hive's default values

## What changes were proposed in this pull request?
When we create the HiveConf for metastore client, we use a Hadoop Conf as the base, which may contain Hive settings in hive-site.xml (https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/internal/SharedState.scala#L49). However, HiveConf's initialize function basically ignores the base Hadoop Conf and always its default values (i.e. settings with non-null default values) as the base (https://github.com/apache/hive/blob/release-1.2.1/common/src/java/org/apache/hadoop/hive/conf/HiveConf.java#L2687). So, even a user put javax.jdo.option.ConnectionURL in hive-site.xml, it is not used and Hive will use its default, which is jdbc:derby:;databaseName=metastore_db;create=true.

This issue only shows up when `spark.sql.hive.metastore.jars` is not set to builtin.

## How was this patch tested?
New test in HiveSparkSubmitSuite.

Author: Yin Huai <yhuai@databricks.com>

Closes #14497 from yhuai/SPARK-16901.

1 files changed, 21 insertions, 3 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala
index ef69ac76f2..3bf4ed5ab4 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala
@@ -141,14 +141,32 @@ private[hive] class HiveClientImpl(
         // so we should keep `conf` and reuse the existing instance of `CliSessionState`.
         originalState
       } else {
-        val hiveConf = new HiveConf(hadoopConf, classOf[SessionState])
+        val hiveConf = new HiveConf(classOf[SessionState])
+        // 1: we set all confs in the hadoopConf to this hiveConf.
+        // This hadoopConf contains user settings in Hadoop's core-site.xml file
+        // and Hive's hive-site.xml file. Note, we load hive-site.xml file manually in
+        // SharedState and put settings in this hadoopConf instead of relying on HiveConf
+        // to load user settings. Otherwise, HiveConf's initialize method will override
+        // settings in the hadoopConf. This issue only shows up when spark.sql.hive.metastore.jars
+        // is not set to builtin. When spark.sql.hive.metastore.jars is builtin, the classpath
+        // has hive-site.xml. So, HiveConf will use that to override its default values.
+        hadoopConf.iterator().asScala.foreach { entry =>
+          val key = entry.getKey
+          val value = entry.getValue
+          if (key.toLowerCase.contains("password")) {
+            logDebug(s"Applying Hadoop and Hive config to Hive Conf: $key=xxx")
+          } else {
+            logDebug(s"Applying Hadoop and Hive config to Hive Conf: $key=$value")
+          }
+          hiveConf.set(key, value)
+        }
         // HiveConf is a Hadoop Configuration, which has a field of classLoader and
         // the initial value will be the current thread's context class loader
         // (i.e. initClassLoader at here).
         // We call initialConf.setClassLoader(initClassLoader) at here to make
         // this action explicit.
         hiveConf.setClassLoader(initClassLoader)
-        // First, we set all spark confs to this hiveConf.
+        // 2: we set all spark confs to this hiveConf.
         sparkConf.getAll.foreach { case (k, v) =>
           if (k.toLowerCase.contains("password")) {
             logDebug(s"Applying Spark config to Hive Conf: $k=xxx")
@@ -157,7 +175,7 @@ private[hive] class HiveClientImpl(
           }
           hiveConf.set(k, v)
         }
-        // Second, we set all entries in config to this hiveConf.
+        // 3: we set all entries in config to this hiveConf.
         extraConfig.foreach { case (k, v) =>
           if (k.toLowerCase.contains("password")) {
             logDebug(s"Applying extra config to HiveConf: $k=xxx")