text: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  # 
  #     http://www.apache.org/licenses/LICENSE-2.0
  # 
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  #
  
  from __future__ import with_statement
  
  import logging
  import os
  import random
  import shutil
  import subprocess
  import sys
  import tempfile
  import time
  import urllib2
  from optparse import OptionParser
  from sys import stderr
  import boto
  from boto.ec2.blockdevicemapping import BlockDeviceMapping, EBSBlockDeviceType
  from boto import ec2
  
  # A static URL from which to figure out the latest Mesos EC2 AMI
  LATEST_AMI_URL = "https://s3.amazonaws.com/mesos-images/ids/latest-spark-0.7"
  
  
  # Configure and parse our command-line arguments
  def parse_args():
    parser = OptionParser(usage="spark-ec2 [options] <action> <cluster_name>"
        + "\n\n<action> can be: launch, destroy, login, stop, start, get-master",
        add_help_option=False)
    parser.add_option("-h", "--help", action="help",
                      help="Show this help message and exit")
    parser.add_option("-s", "--slaves", type="int", default=1,
        help="Number of slaves to launch (default: 1)")
    parser.add_option("-w", "--wait", type="int", default=120,
        help="Seconds to wait for nodes to start (default: 120)")
    parser.add_option("-k", "--key-pair",
        help="Key pair to use on instances")
    parser.add_option("-i", "--identity-file", 
        help="SSH private key file to use for logging into instances")
    parser.add_option("-t", "--instance-type", default="m1.large",
        help="Type of instance to launch (default: m1.large). " +
             "WARNING: must be 64-bit; small instances won't work")
    parser.add_option("-m", "--master-instance-type", default="",
        help="Master instance type (leave empty for same as instance-type)")
    parser.add_option("-r", "--region", default="us-east-1",
        help="EC2 region zone to launch instances in")
    parser.add_option("-z", "--zone", default="",
        help="Availability zone to launch instances in, or 'all' to spread " +
             "slaves across multiple (an additional $0.01/Gb for bandwidth" +
             "between zones applies)")
    parser.add_option("-a", "--ami", default="latest",
        help="Amazon Machine Image ID to use, or 'latest' to use latest " +
             "available AMI (default: latest)")
    parser.add_option("-D", metavar="[ADDRESS:]PORT", dest="proxy_port", 
        help="Use SSH dynamic port forwarding to create a SOCKS proxy at " +
              "the given local address (for use with login)")
    parser.add_option("--resume", action="store_true", default=False,
        help="Resume installation on a previously launched cluster " +
             "(for debugging)")
    parser.add_option("--ebs-vol-size", metavar="SIZE", type="int", default=0,
        help="Attach a new EBS volume of size SIZE (in GB) to each node as " +
             "/vol. The volumes will be deleted when the instances terminate. " +
             "Only possible on EBS-backed AMIs.")
    parser.add_option("--swap", metavar="SWAP", type="int", default=1024,
        help="Swap space to set up per node, in MB (default: 1024)")
    parser.add_option("--spot-price", metavar="PRICE", type="float",
        help="If specified, launch slaves as spot instances with the given " +
              "maximum price (in dollars)")
    parser.add_option("--cluster-type", type="choice", metavar="TYPE",
        choices=["mesos", "standalone"], default="standalone",
        help="'mesos' for a Mesos cluster, 'standalone' for a standalone " +
             "Spark cluster (default: standalone)")
    parser.add_option("--ganglia", action="store_true", default=True,
        help="Setup Ganglia monitoring on cluster (default: on). NOTE: " +
             "the Ganglia page will be publicly accessible")
    parser.add_option("--no-ganglia", action="store_false", dest="ganglia",
        help="Disable Ganglia monitoring for the cluster")
    parser.add_option("--old-scripts", action="store_true", default=False,
        help="Use old mesos-ec2 scripts, for Spark <= 0.6 AMIs")
    parser.add_option("-u", "--user", default="root",
        help="The SSH user you want to connect as (default: root)")
    parser.add_option("--delete-groups", action="store_true", default=False,
        help="When destroying a cluster, delete the security groups that were created")
              
    (opts, args) = parser.parse_args()
    if len(args) != 2:
      parser.print_help()
      sys.exit(1)
    (action, cluster_name) = args
    if opts.identity_file == None and action in ['launch', 'login', 'start']:
      print >> stderr, ("ERROR: The -i or --identity-file argument is " +
                        "required for " + action)
      sys.exit(1)
    if opts.cluster_type not in ["mesos", "standalone"] and action == "launch":
      print >> stderr, ("ERROR: Invalid cluster type: " + opts.cluster_type)
      sys.exit(1)
    
    # Boto config check
    # http://boto.cloudhackers.com/en/latest/boto_config_tut.html
    home_dir = os.getenv('HOME')
    if home_dir == None or not os.path.isfile(home_dir + '/.boto'):
      if not os.path.isfile('/etc/boto.cfg'):
        if os.getenv('AWS_ACCESS_KEY_ID') == None:
          print >> stderr, ("ERROR: The environment variable AWS_ACCESS_KEY_ID " +
                            "must be set")
          sys.exit(1)
        if os.getenv('AWS_SECRET_ACCESS_KEY') == None:
          print >> stderr, ("ERROR: The environment variable AWS_SECRET_ACCESS_KEY " +
                            "must be set")
          sys.exit(1)
    return (opts, action, cluster_name)
  
  
  # Get the EC2 security group of the given name, creating it if it doesn't exist
  def get_or_make_group(conn, name):
    groups = conn.get_all_security_groups()
    group = [g for g in groups if g.name == name]
    if len(group) > 0:
      return group[0]
    else:
      print "Creating security group " + name
      return conn.create_security_group(name, "Spark EC2 group")
  
  
  # Wait for a set of launched instances to exit the "pending" state
  # (i.e. either to start running or to fail and be terminated)
  def wait_for_instances(conn, instances):
    while True:
      for i in instances:
        i.update()
      if len([i for i in instances if i.state == 'pending']) > 0:
        time.sleep(5)
      else:
        return
  
  
  # Check whether a given EC2 instance object is in a state we consider active,
  # i.e. not terminating or terminated. We count both stopping and stopped as
  # active since we can restart stopped clusters.
  def is_active(instance):
    return (instance.state in ['pending', 'running', 'stopping', 'stopped'])
  
  
  # Launch a cluster of the given name, by setting up its security groups,
  # and then starting new instances in them.
  # Returns a tuple of EC2 reservation objects for the master, slave
  # and zookeeper instances (in that order).
  # Fails if there already instances running in the cluster's groups.
  def launch_cluster(conn, opts, cluster_name):
    print "Setting up security groups..."
    master_group = get_or_make_group(conn, cluster_name + "-master")
    slave_group = get_or_make_group(conn, cluster_name + "-slaves")
    zoo_group = get_or_make_group(conn, cluster_name + "-zoo")
    if master_group.rules == []: # Group was just now created
      master_group.authorize(src_group=master_group)
      master_group.authorize(src_group=slave_group)
      master_group.authorize(src_group=zoo_group)
      master_group.authorize('tcp', 22, 22, '0.0.0.0/0')
      master_group.authorize('tcp', 8080, 8081, '0.0.0.0/0')
      master_group.authorize('tcp', 50030, 50030, '0.0.0.0/0')
      master_group.authorize('tcp', 50070, 50070, '0.0.0.0/0')
      master_group.authorize('tcp', 60070, 60070, '0.0.0.0/0')
      if opts.cluster_type == "mesos":
        master_group.authorize('tcp', 38090, 38090, '0.0.0.0/0')
      if opts.ganglia:
        master_group.authorize('tcp', 5080, 5080, '0.0.0.0/0')
    if slave_group.rules == []: # Group was just now created
      slave_group.authorize(src_group=master_group)
      slave_group.authorize(src_group=slave_group)
      slave_group.authorize(src_group=zoo_group)
      slave_group.authorize('tcp', 22, 22, '0.0.0.0/0')
      slave_group.authorize('tcp', 8080, 8081, '0.0.0.0/0')
      slave_group.authorize('tcp', 50060, 50060, '0.0.0.0/0')
      slave_group.authorize('tcp', 50075, 50075, '0.0.0.0/0')
      slave_group.authorize('tcp', 60060, 60060, '0.0.0.0/0')
      slave_group.authorize('tcp', 60075, 60075, '0.0.0.0/0')
    if zoo_group.rules == []: # Group was just now created
      zoo_group.authorize(src_group=master_group)
      zoo_group.authorize(src_group=slave_group)
      zoo_group.authorize(src_group=zoo_group)
      zoo_group.authorize('tcp', 22, 22, '0.0.0.0/0')
      zoo_group.authorize('tcp', 2181, 2181, '0.0.0.0/0')
      zoo_group.authorize('tcp', 2888, 2888, '0.0.0.0/0')
      zoo_group.authorize('tcp', 3888, 3888, '0.0.0.0/0')
  
    # Check if instances are already running in our groups
    active_nodes = get_existing_cluster(conn, opts, cluster_name,
                                        die_on_error=False)
    if any(active_nodes):
      print >> stderr, ("ERROR: There are already instances running in " +
          "group %s, %s or %s" % (master_group.name, slave_group.name, zoo_group.name))
      sys.exit(1)
  
    # Figure out the latest AMI from our static URL
    if opts.ami == "latest":
      try:
        opts.ami = urllib2.urlopen(LATEST_AMI_URL).read().strip()
        print "Latest Spark AMI: " + opts.ami
      except:
        print >> stderr, "Could not read " + LATEST_AMI_URL
        sys.exit(1)
  
    print "Launching instances..."
  
    try:
      image = conn.get_all_images(image_ids=[opts.ami])[0]
    except:
      print >> stderr, "Could not find AMI " + opts.ami
      sys.exit(1)
  
    # Create block device mapping so that we can add an EBS volume if asked to
    block_map = BlockDeviceMapping()
    if opts.ebs_vol_size > 0:
      device = EBSBlockDeviceType()
      device.size = opts.ebs_vol_size
      device.delete_on_termination = True
      block_map["/dev/sdv"] = device
  
    # Launch slaves
    if opts.spot_price != None:
      # Launch spot instances with the requested price
      print ("Requesting %d slaves as spot instances with price $%.3f" %
             (opts.slaves, opts.spot_price))
      zones = get_zones(conn, opts)
      num_zones = len(zones)
      i = 0
      my_req_ids = []
      for zone in zones:
        num_slaves_this_zone = get_partition(opts.slaves, num_zones, i)
        slave_reqs = conn.request_spot_instances(
            price = opts.spot_price,
            image_id = opts.ami,
            launch_group = "launch-group-%s" % cluster_name,
            placement = zone,
            count = num_slaves_this_zone,
            key_name = opts.key_pair,
            security_groups = [slave_group],
            instance_type = opts.instance_type,
            block_device_map = block_map)
        my_req_ids += [req.id for req in slave_reqs]
        i += 1
      
      print "Waiting for spot instances to be granted..."
      try:
        while True:
          time.sleep(10)
          reqs = conn.get_all_spot_instance_requests()
          id_to_req = {}
          for r in reqs:
            id_to_req[r.id] = r
          active_instance_ids = []
          for i in my_req_ids:
            if i in id_to_req and id_to_req[i].state == "active":
              active_instance_ids.append(id_to_req[i].instance_id)
          if len(active_instance_ids) == opts.slaves:
            print "All %d slaves granted" % opts.slaves
            reservations = conn.get_all_instances(active_instance_ids)
            slave_nodes = []
            for r in reservations:
              slave_nodes += r.instances
            break
          else:
            print "%d of %d slaves granted, waiting longer" % (
              len(active_instance_ids), opts.slaves)
      except:
        print "Canceling spot instance requests"
        conn.cancel_spot_instance_requests(my_req_ids)
        # Log a warning if any of these requests actually launched instances:
        (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
            conn, opts, cluster_name, die_on_error=False)
        running = len(master_nodes) + len(slave_nodes) + len(zoo_nodes)
        if running:
          print >> stderr, ("WARNING: %d instances are still running" % running)
        sys.exit(0)
    else:
      # Launch non-spot instances
      zones = get_zones(conn, opts)
      num_zones = len(zones)
      i = 0
      slave_nodes = []
      for zone in zones:
        num_slaves_this_zone = get_partition(opts.slaves, num_zones, i)
        if num_slaves_this_zone > 0:
          slave_res = image.run(key_name = opts.key_pair,
                                security_groups = [slave_group],
                                instance_type = opts.instance_type,
                                placement = zone,
                                min_count = num_slaves_this_zone,
                                max_count = num_slaves_this_zone,
                                block_device_map = block_map)
          slave_nodes += slave_res.instances
          print "Launched %d slaves in %s, regid = %s" % (num_slaves_this_zone,
                                                          zone, slave_res.id)
        i += 1
  
    # Launch masters
    master_type = opts.master_instance_type
    if master_type == "":
      master_type = opts.instance_type
    if opts.zone == 'all':
      opts.zone = random.choice(conn.get_all_zones()).name
    master_res = image.run(key_name = opts.key_pair,
                           security_groups = [master_group],
                           instance_type = master_type,
                           placement = opts.zone,
                           min_count = 1,
                           max_count = 1,
                           block_device_map = block_map)
    master_nodes = master_res.instances
    print "Launched master in %s, regid = %s" % (zone, master_res.id)
  
    zoo_nodes = []
  
    # Return all the instances
    return (master_nodes, slave_nodes, zoo_nodes)
  
  
  # Get the EC2 instances in an existing cluster if available.
  # Returns a tuple of lists of EC2 instance objects for the masters,
  # slaves and zookeeper nodes (in that order).
  def get_existing_cluster(conn, opts, cluster_name, die_on_error=True):
    print "Searching for existing cluster " + cluster_name + "..."
    reservations = conn.get_all_instances()
    master_nodes = []
    slave_nodes = []
    zoo_nodes = []
    for res in reservations:
      active = [i for i in res.instances if is_active(i)]
      if len(active) > 0:
        group_names = [g.name for g in res.groups]
        if group_names == [cluster_name + "-master"]:
          master_nodes += res.instances
        elif group_names == [cluster_name + "-slaves"]:
          slave_nodes += res.instances
        elif group_names == [cluster_name + "-zoo"]:
          zoo_nodes += res.instances
    if any((master_nodes, slave_nodes, zoo_nodes)):
      print ("Found %d master(s), %d slaves, %d ZooKeeper nodes" %
             (len(master_nodes), len(slave_nodes), len(zoo_nodes)))
    if (master_nodes != [] and slave_nodes != []) or not die_on_error:
      return (master_nodes, slave_nodes, zoo_nodes)
    else:
      if master_nodes == [] and slave_nodes != []:
        print "ERROR: Could not find master in group " + cluster_name + "-master"
      elif master_nodes != [] and slave_nodes == []:
        print "ERROR: Could not find slaves in group " + cluster_name + "-slaves"
      else:
        print "ERROR: Could not find any existing cluster"
      sys.exit(1)
  
  
  # Deploy configuration files and run setup scripts on a newly launched
  # or started EC2 cluster.
  def setup_cluster(conn, master_nodes, slave_nodes, zoo_nodes, opts, deploy_ssh_key):
    master = master_nodes[0].public_dns_name
    if deploy_ssh_key:
      print "Copying SSH key %s to master..." % opts.identity_file
      ssh(master, opts, 'mkdir -p ~/.ssh')
      scp(master, opts, opts.identity_file, '~/.ssh/id_rsa')
      ssh(master, opts, 'chmod 600 ~/.ssh/id_rsa')
  
    if opts.cluster_type == "mesos":
      modules = ['ephemeral-hdfs', 'persistent-hdfs', 'mesos']
    elif opts.cluster_type == "standalone":
      modules = ['ephemeral-hdfs', 'persistent-hdfs', 'spark-standalone']
  
    if opts.ganglia:
      modules.append('ganglia')
  
    if not opts.old_scripts:
      # NOTE: We should clone the repository before running deploy_files to
      # prevent ec2-variables.sh from being overwritten
      ssh(master, opts, "rm -rf spark-ec2 && git clone https://github.com/mesos/spark-ec2.git")
  
    print "Deploying files to master..."
    deploy_files(conn, "deploy.generic", opts, master_nodes, slave_nodes,
            zoo_nodes, modules)
  
    print "Running setup on master..."
    if opts.old_scripts:
      if opts.cluster_type == "mesos":
        setup_mesos_cluster(master, opts)
      elif opts.cluster_type == "standalone":
        setup_standalone_cluster(master, slave_nodes, opts)
    else:
      setup_spark_cluster(master, opts)
    print "Done!"
  
  def setup_mesos_cluster(master, opts):
    ssh(master, opts, "chmod u+x mesos-ec2/setup")
    ssh(master, opts, "mesos-ec2/setup %s %s %s %s" %
        ("generic", "none", "master", opts.swap))
  
  def setup_standalone_cluster(master, slave_nodes, opts):
    slave_ips = '\n'.join([i.public_dns_name for i in slave_nodes])
    ssh(master, opts, "echo \"%s\" > spark/conf/slaves" % (slave_ips))
    ssh(master, opts, "/root/spark/bin/start-all.sh")
    
  def setup_spark_cluster(master, opts):
    ssh(master, opts, "chmod u+x spark-ec2/setup.sh")
    ssh(master, opts, "spark-ec2/setup.sh")
    if opts.cluster_type == "mesos":
      print "Mesos cluster started at http://%s:8080" % master
    elif opts.cluster_type == "standalone":
      print "Spark standalone cluster started at http://%s:8080" % master
  
    if opts.ganglia:
      print "Ganglia started at http://%s:5080/ganglia" % master
  
  
  # Wait for a whole cluster (masters, slaves and ZooKeeper) to start up
  def wait_for_cluster(conn, wait_secs, master_nodes, slave_nodes, zoo_nodes):
    print "Waiting for instances to start up..."
    time.sleep(5)
    wait_for_instances(conn, master_nodes)
    wait_for_instances(conn, slave_nodes)
    if zoo_nodes != []:
      wait_for_instances(conn, zoo_nodes)
    print "Waiting %d more seconds..." % wait_secs
    time.sleep(wait_secs)
  
  
  # Get number of local disks available for a given EC2 instance type.
  def get_num_disks(instance_type):
    # From http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?InstanceStorage.html
    disks_by_instance = {
      "m1.small":    1,
      "m1.medium":   1,
      "m1.large":    2,
      "m1.xlarge":   4,
      "t1.micro":    1,
      "c1.medium":   1,
      "c1.xlarge":   4,
      "m2.xlarge":   1,
      "m2.2xlarge":  1,
      "m2.4xlarge":  2,
      "cc1.4xlarge": 2,
      "cc2.8xlarge": 4,
      "cg1.4xlarge": 2
    }
    if instance_type in disks_by_instance:
      return disks_by_instance[instance_type]
    else:
      print >> stderr, ("WARNING: Don't know number of disks on instance type %s; assuming 1"
                        % instance_type)
      return 1
  
  
  # Deploy the configuration file templates in a given local directory to
  # a cluster, filling in any template parameters with information about the
  # cluster (e.g. lists of masters and slaves). Files are only deployed to
  # the first master instance in the cluster, and we expect the setup
  # script to be run on that instance to copy them to other nodes.
  def deploy_files(conn, root_dir, opts, master_nodes, slave_nodes, zoo_nodes,
          modules):
    active_master = master_nodes[0].public_dns_name
  
    num_disks = get_num_disks(opts.instance_type)
    hdfs_data_dirs = "/mnt/ephemeral-hdfs/data"
    mapred_local_dirs = "/mnt/hadoop/mrlocal"
    spark_local_dirs = "/mnt/spark"
    if num_disks > 1:
      for i in range(2, num_disks + 1):
        hdfs_data_dirs += ",/mnt%d/ephemeral-hdfs/data" % i
        mapred_local_dirs += ",/mnt%d/hadoop/mrlocal" % i
        spark_local_dirs += ",/mnt%d/spark" % i
  
    if zoo_nodes != []:
      zoo_list = '\n'.join([i.public_dns_name for i in zoo_nodes])
      cluster_url = "zoo://" + ",".join(
          ["%s:2181/mesos" % i.public_dns_name for i in zoo_nodes])
    elif opts.cluster_type == "mesos":
      zoo_list = "NONE"
      cluster_url = "%s:5050" % active_master
    elif opts.cluster_type == "standalone":
      zoo_list = "NONE"
      cluster_url = "%s:7077" % active_master
  
    template_vars = {
      "master_list": '\n'.join([i.public_dns_name for i in master_nodes]),
      "active_master": active_master,
      "slave_list": '\n'.join([i.public_dns_name for i in slave_nodes]),
      "zoo_list": zoo_list,
      "cluster_url": cluster_url,
      "hdfs_data_dirs": hdfs_data_dirs,
      "mapred_local_dirs": mapred_local_dirs,
      "spark_local_dirs": spark_local_dirs,
      "swap": str(opts.swap),
      "modules": '\n'.join(modules)
    }
  
    # Create a temp directory in which we will place all the files to be
    # deployed after we substitue template parameters in them
    tmp_dir = tempfile.mkdtemp()
    for path, dirs, files in os.walk(root_dir):
      if path.find(".svn") == -1:
        dest_dir = os.path.join('/', path[len(root_dir):])
        local_dir = tmp_dir + dest_dir
        if not os.path.exists(local_dir):
          os.makedirs(local_dir)
        for filename in files:
          if filename[0] not in '#.~' and filename[-1] != '~':
            dest_file = os.path.join(dest_dir, filename)
            local_file = tmp_dir + dest_file
            with open(os.path.join(path, filename)) as src:
              with open(local_file, "w") as dest:
                text = src.read()
                for key in template_vars:
                  text = text.replace("{{" + key + "}}", template_vars[key])
                dest.write(text)
                dest.close()
    # rsync the whole directory over to the master machine
    command = (("rsync -rv -e 'ssh -o StrictHostKeyChecking=no -i %s' " + 
        "'%s/' '%s@%s:/'") % (opts.identity_file, tmp_dir, opts.user, active_master))
    subprocess.check_call(command, shell=True)
    # Remove the temp directory we created above
    shutil.rmtree(tmp_dir)
  
  
  # Copy a file to a given host through scp, throwing an exception if scp fails
  def scp(host, opts, local_file, dest_file):
    subprocess.check_call(
        "scp -q -o StrictHostKeyChecking=no -i %s '%s' '%s@%s:%s'" %
        (opts.identity_file, local_file, opts.user, host, dest_file), shell=True)
  
  
  # Run a command on a host through ssh, retrying up to two times
  # and then throwing an exception if ssh continues to fail.
  def ssh(host, opts, command):
    tries = 0
    while True:
      try:
        return subprocess.check_call(
          "ssh -t -o StrictHostKeyChecking=no -i %s %s@%s '%s'" %
          (opts.identity_file, opts.user, host, command), shell=True)
      except subprocess.CalledProcessError as e:
        if (tries > 2):
          raise e
        print "Error connecting to host {0}, sleeping 30".format(e)
        time.sleep(30)
        tries = tries + 1
      
      
      
  
  
  # Gets a list of zones to launch instances in
  def get_zones(conn, opts):
    if opts.zone == 'all':
      zones = [z.name for z in conn.get_all_zones()]
    else:
      zones = [opts.zone]
    return zones
  
  
  # Gets the number of items in a partition
  def get_partition(total, num_partitions, current_partitions):
    num_slaves_this_zone = total / num_partitions
    if (total % num_partitions) - current_partitions > 0:
      num_slaves_this_zone += 1
    return num_slaves_this_zone
  
  
  def main():
    (opts, action, cluster_name) = parse_args()
    try:
      conn = ec2.connect_to_region(opts.region)
    except Exception as e:
      print >> stderr, (e)
      sys.exit(1)
  
    # Select an AZ at random if it was not specified.
    if opts.zone == "":
      opts.zone = random.choice(conn.get_all_zones()).name
  
    if action == "launch":
      if opts.resume:
        (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
            conn, opts, cluster_name)
      else:
        (master_nodes, slave_nodes, zoo_nodes) = launch_cluster(
            conn, opts, cluster_name)
        wait_for_cluster(conn, opts.wait, master_nodes, slave_nodes, zoo_nodes)
      setup_cluster(conn, master_nodes, slave_nodes, zoo_nodes, opts, True)
  
    elif action == "destroy":
      response = raw_input("Are you sure you want to destroy the cluster " +
          cluster_name + "?\nALL DATA ON ALL NODES WILL BE LOST!!\n" +
          "Destroy cluster " + cluster_name + " (y/N): ")
      if response == "y":
        (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
            conn, opts, cluster_name, die_on_error=False)
        print "Terminating master..."
        for inst in master_nodes:
          inst.terminate()
        print "Terminating slaves..."
        for inst in slave_nodes:
          inst.terminate()
        if zoo_nodes != []:
          print "Terminating zoo..."
          for inst in zoo_nodes:
            inst.terminate()
        
        # Delete security groups as well
        if opts.delete_groups:
          print "Deleting security groups (this will take some time)..."
          group_names = [cluster_name + "-master", cluster_name + "-slaves", cluster_name + "-zoo"]
          
          attempt = 1;
          while attempt <= 3:
            print "Attempt %d" % attempt
            groups = [g for g in conn.get_all_security_groups() if g.name in group_names]
            success = True
            # Delete individual rules in all groups before deleting groups to
            # remove dependencies between them
            for group in groups:
              print "Deleting rules in security group " + group.name
              for rule in group.rules:
                for grant in rule.grants:
                    success &= group.revoke(ip_protocol=rule.ip_protocol,
                             from_port=rule.from_port,
                             to_port=rule.to_port,
                             src_group=grant)
            
            # Sleep for AWS eventual-consistency to catch up, and for instances
            # to terminate
            time.sleep(30)  # Yes, it does have to be this long :-(
            for group in groups:
              try:
                conn.delete_security_group(group.name)
                print "Deleted security group " + group.name
              except boto.exception.EC2ResponseError:
                success = False;
                print "Failed to delete security group " + group.name
            
            # Unfortunately, group.revoke() returns True even if a rule was not
            # deleted, so this needs to be rerun if something fails
            if success: break;
            
            attempt += 1
            
          if not success:
            print "Failed to delete all security groups after 3 tries."
            print "Try re-running in a few minutes."
  
    elif action == "login":
      (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
          conn, opts, cluster_name)
      master = master_nodes[0].public_dns_name
      print "Logging into master " + master + "..."
      proxy_opt = ""
      if opts.proxy_port != None:
        proxy_opt = "-D " + opts.proxy_port
      subprocess.check_call("ssh -o StrictHostKeyChecking=no -i %s %s %s@%s" %
          (opts.identity_file, proxy_opt, opts.user, master), shell=True)
  
    elif action == "get-master":
      (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(conn, opts, cluster_name)
      print master_nodes[0].public_dns_name
  
    elif action == "stop":
      response = raw_input("Are you sure you want to stop the cluster " +
          cluster_name + "?\nDATA ON EPHEMERAL DISKS WILL BE LOST, " +
          "BUT THE CLUSTER WILL KEEP USING SPACE ON\n" + 
          "AMAZON EBS IF IT IS EBS-BACKED!!\n" +
          "Stop cluster " + cluster_name + " (y/N): ")
      if response == "y":
        (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
            conn, opts, cluster_name, die_on_error=False)
        print "Stopping master..."
        for inst in master_nodes:
          if inst.state not in ["shutting-down", "terminated"]:
            inst.stop()
        print "Stopping slaves..."
        for inst in slave_nodes:
          if inst.state not in ["shutting-down", "terminated"]:
            inst.stop()
        if zoo_nodes != []:
          print "Stopping zoo..."
          for inst in zoo_nodes:
            if inst.state not in ["shutting-down", "terminated"]:
              inst.stop()
  
    elif action == "start":
      (master_nodes, slave_nodes, zoo_nodes) = get_existing_cluster(
          conn, opts, cluster_name)
      print "Starting slaves..."
      for inst in slave_nodes:
        if inst.state not in ["shutting-down", "terminated"]:
          inst.start()
      print "Starting master..."
      for inst in master_nodes:
        if inst.state not in ["shutting-down", "terminated"]:
          inst.start()
      if zoo_nodes != []:
        print "Starting zoo..."
        for inst in zoo_nodes:
          if inst.state not in ["shutting-down", "terminated"]:
            inst.start()
      wait_for_cluster(conn, opts.wait, master_nodes, slave_nodes, zoo_nodes)
      setup_cluster(conn, master_nodes, slave_nodes, zoo_nodes, opts, False)
  
    else:
      print >> stderr, "Invalid action: %s" % action
      sys.exit(1)
  
  
  if __name__ == "__main__":
    logging.basicConfig()
    main()
  