So I'm trying to run a Spark pipeline on EMR, and I'm creating a step like so: 

```
// Build the Spark job submission request
val runSparkJob = new StepConfig()
  .withName("Run Pipeline")
  .withActionOnFailure(ActionOnFailure.TERMINATE_CLUSTER)
  .withHadoopJarStep(
    new HadoopJarStepConfig()
      .withJar(jarS3Path)
      .withMainClass("com.example.SparkApp")
  )

```

Problem is, when I run this, I encounter an exception like so:

```
org.apache.spark.SparkException: A master URL must be set in your configuration

```

The thing is, I'm trying to figure out where to specify the master URL, and I can't seem to find it. Do I specify it when setting up the pipeline run step or do I need to somehow get the master `IP:port` into the application and specify it in the main function?