Configuring Environment Variables in Yarn-Client and Yarn-Cluster Modes

Scenario

Values of some configuration parameters of Spark client vary depending on its work mode (YARN-Client or YARN-Cluster). If you switch Spark client between different modes without first changing values of such configuration parameters, Spark client fails to submit jobs in the new mode.

To avoid this, configure parameters as described in Table 1.

In Yarn-Cluster mode, use the new parameters (path and parameters of Spark server).
In Yarn-Client mode, uses the original parameters.
They are spark.driver.extraClassPath, spark.driver.extraJavaOptions, and spark.driver.extraLibraryPath.

If you choose not to add the parameters in Table 1, Spark client can continue to operate well in either mode but the mode switch requires changes to some of its configuration parameters.

Configuring Parameters

Choose Cluster > Services > Spark2x or Spark > Configurations, click All Configurations, and search for the following parameters and adjust their values:

**Table 1** Parameter description
Parameter	Description	Example Value
spark.yarn.cluster.driver.extraClassPath	Indicates the extraClassPath of the driver in Yarn-cluster mode. Set the parameter to the path and parameters of the server. The original parameter spark.driver.extraClassPath indicates the extraClassPath of Spark client. By using different parameters to separate the settings of Spark server from the settings of Spark client, you can switch Spark client to different modes without changing parameter values.	${BIGDATA_HOME}/common/runtime/security
spark.yarn.cluster.driver.extraJavaOptions	Indicates the extraJavaOptions of Driver in Yarn-Cluster mode and is set to path and parameters of extraJavaOptions of Spark server. The original parameter spark.driver.extraJavaOptions indicates the path of extraJavaOptions of Spark client. By using different parameters to separate the settings of Spark server from the settings of Spark client, you can switch Spark client to different modes without changing parameter values. Specifies the string of extra JVM options transferred to the driver in cluster mode, for example, GC or other log settings. It is improper to set the Spark attribute or heap size in this option. CAUTION: Exercise caution when changing the value of this parameter. If an incorrect value is set, the service fails to be started.	-Xloggc:<LOG_DIR>/indexserver-%p-gc.log -XX:+PrintGCDetails -XX:-OmitStackTraceInFastThrow -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=20 -XX:GCLogFileSize=10M -Dlog4j.configuration=./__spark_conf__/__hadoop_conf__/log4j-executor.properties -Dlog4j.configuration.watch=true -Djava.security.auth.login.config=./__spark_conf__/__hadoop_conf__/jaas-zk.conf -Dzookeeper.server.principal=${ZOOKEEPER_SERVER_PRINCIPAL} -Djava.security.krb5.conf=./__spark_conf__/__hadoop_conf__/kdc.conf -Djetty.version=x.y.z -Dorg.xerial.snappy.tempdir=${BIGDATA_HOME}/tmp -Dcarbon.properties.filepath=./__spark_conf__/__hadoop_conf__/carbon.properties -Djdk.tls.ephemeralDHKeySize=2048 -Dspark.ssl.keyStore=./child.keystore #{java_stack_prefer}

After the parameter settings are modified, click Save, perform operations as prompted, and wait until the settings are saved successfully.
After the Spark server configurations are updated, if Configure Status is Expired, restart the component for the configurations to take effect.

Figure 1 Modifying Spark configurations

On the Spark dashboard page, choose More > Restart Service or Service Rolling Restart, enter the administrator password, and wait until the service restarts.

Components are unavailable during the restart, affecting upper-layer services in the cluster. To minimize the impact, perform this operation during off-peak hours or after confirming that the operation does not have adverse impact.