Change spark-submit command line adding these three options:
--files <location_to_your_app.conf>
--conf 'spark.executor.extraJavaOptions=-Dconfig.resource=app'
--conf 'spark.driver.extraJavaOptions=-Dconfig.resource=app'
Note - Using the --conf 'spark.executor.extraJavaOptions=-Dconfig.resource=app' option will not work when spark submits the driver in client mode. Use --driver-java-options "-Dconfig.resource=app" instead.
If you want to know more about Spark, then do check out this awesome video tutorial: