Cluster Management

/**
 * Cluster Manager for creation of Mesos scheduler and backend
 */
class MesosClusterManager extends ExternalClusterManager {
  /**
   * Checks if the master URL is a Mesos URL
   * @param masterURL The master URL to check
   * @return true if URL starts with "mesos"
   */
  def canCreate(masterURL: String): Boolean
  
  /**
   * Creates a TaskScheduler for the Spark application
   * @param sc SparkContext instance
   * @param masterURL Mesos master URL
   * @return TaskSchedulerImpl instance
   */
  def createTaskScheduler(sc: SparkContext, masterURL: String): TaskScheduler
  
  /**
   * Creates the appropriate scheduler backend based on configuration
   * @param sc SparkContext instance  
   * @param masterURL Mesos master URL
   * @param scheduler TaskScheduler instance
   * @return SchedulerBackend (coarse-grained or fine-grained)
   * @throws SparkException if I/O encryption is enabled (not supported)
   */
  def createSchedulerBackend(
    sc: SparkContext,
    masterURL: String, 
    scheduler: TaskScheduler
  ): SchedulerBackend
  
  /**
   * Initializes the scheduler with the backend
   * @param scheduler TaskScheduler to initialize
   * @param backend SchedulerBackend to use
   */
  def initialize(scheduler: TaskScheduler, backend: SchedulerBackend): Unit
}

import org.apache.spark.{SparkConf, SparkContext}
import org.apache.spark.scheduler.cluster.mesos.MesosClusterManager

// Automatic usage through SparkContext
val conf = new SparkConf()
  .setAppName("MyApp")
  .setMaster("mesos://master:5050")  // Triggers MesosClusterManager usage

val sc = new SparkContext(conf)
// MesosClusterManager.canCreate() returns true for "mesos://" URLs
// createTaskScheduler() and createSchedulerBackend() are called automatically

// Manual usage (not typical)
val clusterManager = new MesosClusterManager()
if (clusterManager.canCreate("mesos://master:5050")) {
  val scheduler = clusterManager.createTaskScheduler(sc, "mesos://master:5050")
  val backend = clusterManager.createSchedulerBackend(sc, "mesos://master:5050", scheduler)
  clusterManager.initialize(scheduler, backend)
}

// Coarse-grained mode (default)
val conf = new SparkConf()
  .setMaster("mesos://master:5050")
  .set("spark.mesos.coarse", "true")
// Creates MesosCoarseGrainedSchedulerBackend

// Fine-grained mode  
val conf = new SparkConf()
  .setMaster("mesos://master:5050")
  .set("spark.mesos.coarse", "false")
// Creates MesosFineGrainedSchedulerBackend

// I/O encryption validation
if (sc.conf.get(IO_ENCRYPTION_ENABLED)) {
  throw new SparkException("I/O encryption is currently not supported in Mesos.")
}

// URL parsing for Mesos master
val MESOS_REGEX = """mesos://(.*)""".r
val mesosUrl = MESOS_REGEX.findFirstMatchIn(masterURL).get.group(1)