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 pipes
  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
  
  class UsageError(Exception):
    pass
  
  # A URL prefix from which to fetch AMI information
  AMI_PREFIX = "https://raw.github.com/mesos/spark-ec2/v2/ami-list"
  
  # 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", help="Amazon Machine Image ID to use")
    parser.add_option("-v", "--spark-version", default="1.0.0",
        help="Version of Spark to use: 'X.Y.Z' or a specific git hash")
    parser.add_option("--spark-git-repo",
        default="https://github.com/apache/spark",
        help="Github repo from which to checkout supplied commit hash")
    parser.add_option("--hadoop-major-version", default="1",
        help="Major version of Hadoop (default: 1)")
    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("--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("-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")
    parser.add_option("--use-existing-master", action="store_true", default=False,
        help="Launch fresh slaves, but use an existing stopped master if possible")
    parser.add_option("--worker-instances", type="int", default=1,
        help="Number of instances per worker: variable SPARK_WORKER_INSTANCES (default: 1)")
    parser.add_option("--master-opts", type="string", default="",
        help="Extra options to give to master through SPARK_MASTER_OPTS variable (e.g -Dspark.worker.timeout=180)")
  
  
  
    (opts, args) = parser.parse_args()
    if len(args) != 2:
      parser.print_help()
      sys.exit(1)
    (action, cluster_name) = args
  
    # 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'])
  
  # Return correct versions of Spark and Shark, given the supplied Spark version
  def get_spark_shark_version(opts):
    spark_shark_map = {"0.7.3": "0.7.1", "0.8.0": "0.8.0", "0.8.1": "0.8.1", "0.9.0": "0.9.0", 
      "0.9.1": "0.9.1", "1.0.0": "1.0.0"}
    version = opts.spark_version.replace("v", "")
    if version not in spark_shark_map:
      print >> stderr, "Don't know about Spark version: %s" % version
      sys.exit(1)
    return (version, spark_shark_map[version])
  
  # Attempt to resolve an appropriate AMI given the architecture and
  # region of the request.
  def get_spark_ami(opts):
    instance_types = {
      "m1.small":    "pvm",
      "m1.medium":   "pvm",
      "m1.large":    "pvm",
      "m1.xlarge":   "pvm",
      "t1.micro":    "pvm",
      "c1.medium":   "pvm",
      "c1.xlarge":   "pvm",
      "m2.xlarge":   "pvm",
      "m2.2xlarge":  "pvm",
      "m2.4xlarge":  "pvm",
      "cc1.4xlarge": "hvm",
      "cc2.8xlarge": "hvm",
      "cg1.4xlarge": "hvm",
      "hs1.8xlarge": "hvm",
      "hi1.4xlarge": "hvm",
      "m3.xlarge":   "hvm",
      "m3.2xlarge":  "hvm",
      "cr1.8xlarge": "hvm",
      "i2.xlarge":   "hvm",
      "i2.2xlarge":  "hvm",
      "i2.4xlarge":  "hvm",
      "i2.8xlarge":  "hvm",
      "c3.large":    "pvm",
      "c3.xlarge":   "pvm",
      "c3.2xlarge":  "pvm",
      "c3.4xlarge":  "pvm",
      "c3.8xlarge":  "pvm",
      "r3.large":    "hvm",
      "r3.xlarge":   "hvm",
      "r3.2xlarge":  "hvm",
      "r3.4xlarge":  "hvm",
      "r3.8xlarge":  "hvm"
    }
    if opts.instance_type in instance_types:
      instance_type = instance_types[opts.instance_type]
    else:
      instance_type = "pvm"
      print >> stderr,\
          "Don't recognize %s, assuming type is pvm" % opts.instance_type
  
    ami_path = "%s/%s/%s" % (AMI_PREFIX, opts.region, instance_type)
    try:
      ami = urllib2.urlopen(ami_path).read().strip()
      print "Spark AMI: " + ami
    except:
      print >> stderr, "Could not resolve AMI at: " + ami_path
      sys.exit(1)
  
    return ami
  
  # 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 and slaves
  # Fails if there already instances running in the cluster's groups.
  def launch_cluster(conn, opts, cluster_name):
    if opts.identity_file is None:
      print >> stderr, "ERROR: Must provide an identity file (-i) for ssh connections."
      sys.exit(1)
    if opts.key_pair is None:
      print >> stderr, "ERROR: Must provide a key pair name (-k) to use on instances."
      sys.exit(1)
    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")
    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('tcp', 22, 22, '0.0.0.0/0')
      master_group.authorize('tcp', 8080, 8081, '0.0.0.0/0')
      master_group.authorize('tcp', 19999, 19999, '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')
      master_group.authorize('tcp', 4040, 4045, '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('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')
  
    # Check if instances are already running in our groups
    existing_masters, existing_slaves = get_existing_cluster(conn, opts, cluster_name,
                                                             die_on_error=False)
    if existing_slaves or (existing_masters and not opts.use_existing_master):
      print >> stderr, ("ERROR: There are already instances running in " +
          "group %s or %s" % (master_group.name, slave_group.name))
      sys.exit(1)
  
    # Figure out Spark AMI
    if opts.ami is None:
      opts.ami = get_spark_ami(opts)
    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) = get_existing_cluster(
            conn, opts, cluster_name, die_on_error=False)
        running = len(master_nodes) + len(slave_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 or resume masters
    if existing_masters:
      print "Starting master..."
      for inst in existing_masters:
        if inst.state not in ["shutting-down", "terminated"]:
          inst.start()
      master_nodes = existing_masters
    else:
      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)
  
    # Return all the instances
    return (master_nodes, slave_nodes)
  
  
  # Get the EC2 instances in an existing cluster if available.
  # Returns a tuple of lists of EC2 instance objects for the masters and slaves
  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 = []
    for res in reservations:
      active = [i for i in res.instances if is_active(i)]
      for inst in active:
        group_names = [g.name for g in inst.groups]
        if group_names == [cluster_name + "-master"]:
          master_nodes.append(inst)
        elif group_names == [cluster_name + "-slaves"]:
          slave_nodes.append(inst)
    if any((master_nodes, slave_nodes)):
      print ("Found %d master(s), %d slaves" %
             (len(master_nodes), len(slave_nodes)))
    if master_nodes != [] or not die_on_error:
      return (master_nodes, slave_nodes)
    else:
      if master_nodes == [] and slave_nodes != []:
        print >> sys.stderr, "ERROR: Could not find master in group " + cluster_name + "-master"
      else:
        print >> sys.stderr, "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, opts, deploy_ssh_key):
    master = master_nodes[0].public_dns_name
    if deploy_ssh_key:
      print "Generating cluster's SSH key on master..."
      key_setup = """
        [ -f ~/.ssh/id_rsa ] ||
          (ssh-keygen -q -t rsa -N '' -f ~/.ssh/id_rsa &&
           cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys)
      """
      ssh(master, opts, key_setup)
      dot_ssh_tar = ssh_read(master, opts, ['tar', 'c', '.ssh'])
      print "Transferring cluster's SSH key to slaves..."
      for slave in slave_nodes:
        print slave.public_dns_name
        ssh_write(slave.public_dns_name, opts, ['tar', 'x'], dot_ssh_tar)
  
    modules = ['spark', 'shark', 'ephemeral-hdfs', 'persistent-hdfs',
               'mapreduce', 'spark-standalone', 'tachyon']
  
    if opts.hadoop_major_version == "1":
      modules = filter(lambda x: x != "mapreduce", modules)
  
    if opts.ganglia:
      modules.append('ganglia')
  
    # 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 -b v3")
  
    print "Deploying files to master..."
    deploy_files(conn, "deploy.generic", opts, master_nodes, slave_nodes, modules)
  
    print "Running setup on master..."
    setup_spark_cluster(master, opts)
    print "Done!"
  
  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/sbin/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")
    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):
    print "Waiting for instances to start up..."
    time.sleep(5)
    wait_for_instances(conn, master_nodes)
    wait_for_instances(conn, slave_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,
      "hs1.8xlarge": 24,
      "cr1.8xlarge": 2,
      "hi1.4xlarge": 2,
      "m3.xlarge":   0,
      "m3.2xlarge":  0,
      "i2.xlarge":   1,
      "i2.2xlarge":  2,
      "i2.4xlarge":  4,
      "i2.8xlarge":  8,
      "c3.large":    2,
      "c3.xlarge":   2,
      "c3.2xlarge":  2,
      "c3.4xlarge":  2,
      "c3.8xlarge":  2,
      "r3.large":    1,
      "r3.xlarge":   1,
      "r3.2xlarge":  1,
      "r3.4xlarge":  1,
      "r3.8xlarge":  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, 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
  
    cluster_url = "%s:7077" % active_master
  
    if "." in opts.spark_version:
      # Pre-built spark & shark deploy
      (spark_v, shark_v) = get_spark_shark_version(opts)
    else:
      # Spark-only custom deploy
      spark_v = "%s|%s" % (opts.spark_git_repo, opts.spark_version)
      shark_v = ""
      modules = filter(lambda x: x != "shark", modules)
  
    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]),
      "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),
      "spark_version": spark_v,
      "shark_version": shark_v,
      "hadoop_major_version": opts.hadoop_major_version,
      "spark_worker_instances": "%d" % opts.worker_instances,
      "spark_master_opts": opts.master_opts
    }
  
    # 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', stringify_command(ssh_command(opts)),
        "%s/" % tmp_dir,
        "%s@%s:/" % (opts.user, active_master)
      ]
    subprocess.check_call(command)
    # Remove the temp directory we created above
    shutil.rmtree(tmp_dir)
  
  
  def stringify_command(parts):
    if isinstance(parts, str):
      return parts
    else:
      return ' '.join(map(pipes.quote, parts))
  
  
  def ssh_args(opts):
    parts = ['-o', 'StrictHostKeyChecking=no']
    if opts.identity_file is not None:
      parts += ['-i', opts.identity_file]
    return parts
  
  
  def ssh_command(opts):
    return ['ssh'] + ssh_args(opts)
  
  
  # Run a command on a host through ssh, retrying up to five 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_command(opts) + ['-t', '-t', '%s@%s' % (opts.user, host), stringify_command(command)])
      except subprocess.CalledProcessError as e:
        if (tries > 5):
          # If this was an ssh failure, provide the user with hints.
          if e.returncode == 255:
            raise UsageError("Failed to SSH to remote host {0}.\nPlease check that you have provided the correct --identity-file and --key-pair parameters and try again.".format(host))
          else:
            raise e
        print >> stderr, "Error executing remote command, retrying after 30 seconds: {0}".format(e)
        time.sleep(30)
        tries = tries + 1
  
  # Backported from Python 2.7 for compatiblity with 2.6 (See SPARK-1990)
  def _check_output(*popenargs, **kwargs):
      if 'stdout' in kwargs:
          raise ValueError('stdout argument not allowed, it will be overridden.')
      process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
      output, unused_err = process.communicate()
      retcode = process.poll()
      if retcode:
          cmd = kwargs.get("args")
          if cmd is None:
              cmd = popenargs[0]
          raise subprocess.CalledProcessError(retcode, cmd, output=output)
      return output
  
  
  def ssh_read(host, opts, command):
    return _check_output(
        ssh_command(opts) + ['%s@%s' % (opts.user, host), stringify_command(command)])
  
  
  def ssh_write(host, opts, command, input):
    tries = 0
    while True:
      proc = subprocess.Popen(
          ssh_command(opts) + ['%s@%s' % (opts.user, host), stringify_command(command)],
          stdin=subprocess.PIPE)
      proc.stdin.write(input)
      proc.stdin.close()
      status = proc.wait()
      if status == 0:
        break
      elif (tries > 5):
        raise RuntimeError("ssh_write failed with error %s" % proc.returncode)
      else:
        print >> stderr, "Error {0} while executing remote command, retrying after 30 seconds".format(status)
        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 real_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.slaves <= 0:
        print >> sys.stderr, "ERROR: You have to start at least 1 slave"
        sys.exit(1)
      if opts.resume:
        (master_nodes, slave_nodes) = get_existing_cluster(
            conn, opts, cluster_name)
      else:
        (master_nodes, slave_nodes) = launch_cluster(
            conn, opts, cluster_name)
        wait_for_cluster(conn, opts.wait, master_nodes, slave_nodes)
      setup_cluster(conn, master_nodes, slave_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) = 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()
  
        # 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"]
  
          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) = 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_command(opts) + proxy_opt + ['-t', '-t', "%s@%s" % (opts.user, master)])
  
    elif action == "get-master":
      (master_nodes, slave_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" +
          "All data on spot-instance slaves will be lost.\n" +
          "Stop cluster " + cluster_name + " (y/N): ")
      if response == "y":
        (master_nodes, slave_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"]:
            if inst.spot_instance_request_id:
              inst.terminate()
            else:
              inst.stop()
  
    elif action == "start":
      (master_nodes, slave_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()
      wait_for_cluster(conn, opts.wait, master_nodes, slave_nodes)
      setup_cluster(conn, master_nodes, slave_nodes, opts, False)
  
    else:
      print >> stderr, "Invalid action: %s" % action
      sys.exit(1)
  
  
  def main():
    try:
      real_main()
    except UsageError, e:
      print >> stderr, "\nError:\n", e
      sys.exit(1)
  
  
  if __name__ == "__main__":
    logging.basicConfig()
    main()
  