Spark on YARN + Secured hbase

Question

I am submitting a job to YARN (on spark 2.1.1 + kafka 0.10.2.1) which connects to a secured hbase cluster. This job, performs just fine when i am running in \"local\" mode

Answer 1

You are not alone in the quest for Kerberos auth to HBase from Spark, cf. SPARK-12279

A little-known fact is that Spark now generates Hadoop "auth tokens" for Yarn, HDFS, Hive, HBase on startup. These tokens are then broadcasted to the executors, so that they don't have to mess again with Kerberos auth, keytabs, etc.

The first problem is that it's not explicitly documented, and in case of failure the errors are hidden by default (i.e. most people don't connect to HBase with Kerberos, so it's usually pointless to state that the HBase JARs are not in the CLASSPATH and no HBase token was created... usually.)
To log all details about these tokens, you have to set the log level for org.apache.spark.deploy.yarn.Client to DEBUG.

The second problem is that beyond the properties, Spark supports many env variables, some documented, some not documented, and some actually deprecated.
For instance, SPARK_CLASSPATH is now deprecated, and its content actually injected in Spark properties spark.driver / spark.executor.extraClassPath.
But SPARK_DIST_CLASSPATH is still in use, and in the Cloudera distro for example, it is used to inject the core Hadoop libs & config into the Spark "launcher" so that it can bootstrap a YARN-cluster execution, before the driver is started (i.e. before spark.driver.extraClassPath is evaluated).
Other variables of interest are

• HADOOP_CONF_DIR
• SPARK_CONF_DIR
• SPARK_EXTRA_LIB_PATH
• SPARK_SUBMIT_OPTS
• SPARK_PRINT_LAUNCH_COMMAND

The third problem is that, in some specific cases (e.g. YARN-cluster mode in the Cloudera distro), the Spark property spark.yarn.tokens.hbase.enabled is set silently to false -- which makes absolutely no sense, that default is hard-coded to true in Spark source code...!
So you are advised to force it explicitly to true in your job config.

The fourth problem is that, even if the HBase token has been created at startup, then the executors must explicitly use it to authenticate. Fortunately, Cloudera has contributed a "Spark connector" to HBase, to take care of this kind of nasty stuff automatically. It's now part of the HBase client, by default (cf. hbase-spark*.jar).

The fifth problem is that, AFAIK, if you don't have metrics-core*.jar in the CLASSPATH then the HBase connections will fail with puzzling (and unrelated) ZooKepper errors.

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¤¤¤¤¤ How to make that stuff work, with debug traces

# we assume that spark-env.sh and spark-default.conf are already Hadoop-ready,
# and also *almost* HBase-ready (as in a CDH distro);
# especially HADOOP_CONF_DIR and SPARK_DIST_CLASSPATH are expected to be set
# but spark.*.extraClassPath / .extraJavaOptions are expected to be unset

KRB_DEBUG_OPTS="-Dlog4j.logger.org.apache.spark.deploy.yarn.Client=DEBUG -Dlog4j.logger.org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper=DEBUG -Dlog4j.logger.org.apache.hadoop.hbase.client.ConnectionManager$HConnectionImplementation=DEBUG -Dlog4j.logger.org.apache.hadoop.hbase.spark.HBaseContext=DEBUG -Dsun.security.krb5.debug=true -Djava.security.debug=gssloginconfig,configfile,configparser,logincontext"
EXTRA_HBASE_CP=/etc/hbase/conf/:/opt/cloudera/parcels/CDH/lib/hbase/hbase-spark.jar:/opt/cloudera/parcels/CDH/lib/hbase/lib/metrics-core-2.2.0.jar

export SPARK_SUBMIT_OPTS="$KRB_DEBUG_OPTS"
export HADOOP_JAAS_DEBUG=true
export SPARK_PRINT_LAUNCH_COMMAND=True

spark-submit --master yarn-client \
  --files "/etc/spark/conf/log4j.properties#yarn-log4j.properties" \
  --principal XX@Z.NET --keytab /a/b/XX.keytab \
  --conf spark.yarn.tokens.hbase.enabled=true \
  --conf spark.driver.extraClassPath=$EXTRA_HBASE_CP \
  --conf spark.executor.extraClassPath=$EXTRA_HBASE_CP \
  --conf "spark.executor.extraJavaOptions=$KRB_DEBUG_OPTS -Dlog4j.configuration=yarn-log4j.properties" \
  --conf spark.executorEnv.HADOOP_JAAS_DEBUG=true \
  --class TestSparkHBase  TestSparkHBase.jar

spark-submit --master yarn-cluster --conf spark.yarn.report.interval=4000 \
  --files "/etc/spark/conf/log4j.properties#yarn-log4j.properties" \
  --principal XX@Z.NET --keytab /a/b/XX.keytab \
  --conf spark.yarn.tokens.hbase.enabled=true \
  --conf spark.driver.extraClassPath=$EXTRA_HBASE_CP \
  --conf "spark.driver.extraJavaOptions=$KRB_DEBUG_OPTS -Dlog4j.configuration=yarn-log4j.properties" \
  --conf spark.driverEnv.HADOOP_JAAS_DEBUG=true \
  --conf spark.executor.extraClassPath=$EXTRA_HBASE_CP \
  --conf "spark.executor.extraJavaOptions=$KRB_DEBUG_OPTS -Dlog4j.configuration=yarn-log4j.properties" \
  --conf spark.executorEnv.HADOOP_JAAS_DEBUG=true \
  --class TestSparkHBase  TestSparkHBase.jar

PS: when using a HBaseContext you don't need /etc/hbase/conf/ in the executor's CLASSPATH, the conf is propagated automatically.

PPS: I advise you to set log4j.logger.org.apache.zookeeper.ZooKeeper=WARN in log4j.properties because it's verbose, useless, and even confusing (all the interesting stuff is logged at HBase level)

PPS: instead of that verbose SPARK_SUBMIT_OPTS var, you could also list statically the Log4J options in $SPARK_CONF_DIR/log4j.properties and the rest in $SPARK_CONF_DIR/java-opts; same goes for the Spark properties in $SPARK_CONF_DIR/spark-defaults.conf and env variables in $SPARK_CONF_DIR/spark-env.sh

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¤¤¤¤¤ About the "Spark connector" to HBase

Excerpt from the official HBase documentation, chapter 83 Basic Spark

At the root of all Spark and HBase integration is the HBaseContext. The HBaseContext takes in HBase configurations and pushes them to the Spark executors. This allows us to have an HBase Connection per Spark Executor in a static location.

What is not mentioned in the doc is that the HBaseContext uses automatically the HBase "auth token" (when present) to authenticate the executors.

Note also that the doc has an example (in Scala then in Java) of a Spark foreachPartition operation on a RDD, using a BufferedMutator for async bulk load into HBase.