build.sbt

name := "spark-env-var-test"

spark-defaults.conf

spark.mesos.executor.home          /home/ubuntu/spark-1.5.0-SNAPSHOT-bin-custom-spark
spark.mesos.coarse                 true

spark-env.sh

#!/usr/bin/env bash
MESOS_NATIVE_JAVA_LIBRARY=/home/ubuntu/mesos-0.23.0/build/src/.libs/libmesos.so

SPARK_ENV_VAR="1"
NOT_SPARK_ENV_VAR="2"

Test.scala

import java.util.logging.Logger

object Test {
  val logger = Logger.getLogger("Test Logger")

  def main(args: Array[String]): Unit = {
    logger.info(sys.env.get("SPARK_ENV_VAR").toString)
    logger.info(sys.env.get("NOT_SPARK_ENV_VAR").toString)
  }
}