shell.py

# Copyright 2010 Jacob Kaplan-Moss
# Copyright 2011 OpenStack Foundation
# All Rights Reserved.
#
#    Licensed 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.

"""
Command-line interface to the OpenStack Nova API.
"""

from __future__ import print_function
import argparse
import getpass
import logging
import sys

from keystoneclient.auth.identity.generic import password
from keystoneclient.auth.identity.generic import token
from keystoneclient.auth.identity import v3 as identity
from keystoneclient import session as ksession
from oslo_utils import encodeutils
from oslo_utils import strutils
import six

HAS_KEYRING = False
all_errors = ValueError
try:
    import keyring
    HAS_KEYRING = True
except ImportError:
    pass

import novaclient
import novaclient.auth_plugin
from novaclient import client
from novaclient import exceptions as exc
import novaclient.extension
from novaclient.i18n import _
from novaclient.openstack.common import cliutils
from novaclient import utils
from novaclient.v2 import shell as shell_v2

DEFAULT_OS_COMPUTE_API_VERSION = "2"
DEFAULT_NOVA_ENDPOINT_TYPE = 'publicURL'
DEFAULT_NOVA_SERVICE_TYPE = "compute"

logger = logging.getLogger(__name__)


def positive_non_zero_float(text):
    if text is None:
        return None
    try:
        value = float(text)
    except ValueError:
        msg = _("%s must be a float") % text
        raise argparse.ArgumentTypeError(msg)
    if value <= 0:
        msg = _("%s must be greater than 0") % text
        raise argparse.ArgumentTypeError(msg)
    return value


class SecretsHelper(object):
    def __init__(self, args, client):
        self.args = args
        self.client = client
        self.key = None
        self._password = None

    def _validate_string(self, text):
        if text is None or len(text) == 0:
            return False
        return True

    def _make_key(self):
        if self.key is not None:
            return self.key
        keys = [
            self.client.auth_url,
            self.client.projectid,
            self.client.user,
            self.client.region_name,
            self.client.endpoint_type,
            self.client.service_type,
            self.client.service_name,
            self.client.volume_service_name,
        ]
        for (index, key) in enumerate(keys):
            if key is None:
                keys[index] = '?'
            else:
                keys[index] = str(keys[index])
        self.key = "/".join(keys)
        return self.key

    def _prompt_password(self, verify=True):
        pw = None
        if hasattr(sys.stdin, 'isatty') and sys.stdin.isatty():
            # Check for Ctl-D
            try:
                while True:
                    pw1 = getpass.getpass('OS Password: ')
                    if verify:
                        pw2 = getpass.getpass('Please verify: ')
                    else:
                        pw2 = pw1
                    if pw1 == pw2 and self._validate_string(pw1):
                        pw = pw1
                        break
            except EOFError:
                pass
        return pw

    def save(self, auth_token, management_url, tenant_id):
        if not HAS_KEYRING or not self.args.os_cache:
            return
        if (auth_token == self.auth_token and
                management_url == self.management_url):
            # Nothing changed....
            return
        if not all([management_url, auth_token, tenant_id]):
            raise ValueError(_("Unable to save empty management url/auth "
                               "token"))
        value = "|".join([str(auth_token),
                          str(management_url),
                          str(tenant_id)])
        keyring.set_password("novaclient_auth", self._make_key(), value)

    @property
    def password(self):
        # Cache password so we prompt user at most once
        if self._password:
            pass
        elif self._validate_string(self.args.os_password):
            self._password = self.args.os_password
        else:
            verify_pass = strutils.bool_from_string(
                cliutils.env("OS_VERIFY_PASSWORD", default=False), True)
            self._password = self._prompt_password(verify_pass)
        if not self._password:
            raise exc.CommandError(
                'Expecting a password provided via either '
                '--os-password, env[OS_PASSWORD], or '
                'prompted response')
        return self._password

    @property
    def management_url(self):
        if not HAS_KEYRING or not self.args.os_cache:
            return None
        management_url = None
        try:
            block = keyring.get_password('novaclient_auth', self._make_key())
            if block:
                _token, management_url, _tenant_id = block.split('|', 2)
        except all_errors:
            pass
        return management_url

    @property
    def auth_token(self):
        # Now is where it gets complicated since we
        # want to look into the keyring module, if it
        # exists and see if anything was provided in that
        # file that we can use.
        if not HAS_KEYRING or not self.args.os_cache:
            return None
        token = None
        try:
            block = keyring.get_password('novaclient_auth', self._make_key())
            if block:
                token, _management_url, _tenant_id = block.split('|', 2)
        except all_errors:
            pass
        return token

    @property
    def tenant_id(self):
        if not HAS_KEYRING or not self.args.os_cache:
            return None
        tenant_id = None
        try:
            block = keyring.get_password('novaclient_auth', self._make_key())
            if block:
                _token, _management_url, tenant_id = block.split('|', 2)
        except all_errors:
            pass
        return tenant_id


class NovaClientArgumentParser(argparse.ArgumentParser):

    def __init__(self, *args, **kwargs):
        super(NovaClientArgumentParser, self).__init__(*args, **kwargs)

    def error(self, message):
        """error(message: string)

        Prints a usage message incorporating the message to stderr and
        exits.
        """
        self.print_usage(sys.stderr)
        # FIXME(lzyeval): if changes occur in argparse.ArgParser._check_value
        choose_from = ' (choose from'
        progparts = self.prog.partition(' ')
        self.exit(2, _("error: %(errmsg)s\nTry '%(mainp)s help %(subp)s'"
                       " for more information.\n") %
                  {'errmsg': message.split(choose_from)[0],
                   'mainp': progparts[0],
                   'subp': progparts[2]})

    def _get_option_tuples(self, option_string):
        """returns (action, option, value) candidates for an option prefix

        Returns [first candidate] if all candidates refers to current and
        deprecated forms of the same options: "nova boot ... --key KEY"
        parsing succeed because --key could only match --key-name,
        --key_name which are current/deprecated forms of the same option.
        """
        option_tuples = (super(NovaClientArgumentParser, self)
                         ._get_option_tuples(option_string))
        if len(option_tuples) > 1:
            normalizeds = [option.replace('_', '-')
                           for action, option, value in option_tuples]
            if len(set(normalizeds)) == 1:
                return option_tuples[:1]
        return option_tuples


class OpenStackComputeShell(object):
    times = []

    def _append_global_identity_args(self, parser):
        # Register the CLI arguments that have moved to the session object.
        ksession.Session.register_cli_options(parser)

        parser.set_defaults(insecure=cliutils.env('NOVACLIENT_INSECURE',
                            default=False))

        identity.Password.register_argparse_arguments(parser)

        parser.set_defaults(os_username=cliutils.env('OS_USERNAME',
                                                     'NOVA_USERNAME'))
        parser.set_defaults(os_password=cliutils.env('OS_PASSWORD',
                                                     'NOVA_PASSWORD'))
        parser.set_defaults(os_auth_url=cliutils.env('OS_AUTH_URL',
                                                     'NOVA_URL'))

    def get_base_parser(self):
        parser = NovaClientArgumentParser(
            prog='nova',
            description=__doc__.strip(),
            epilog='See "nova help COMMAND" '
                   'for help on a specific command.',
            add_help=False,
            formatter_class=OpenStackHelpFormatter,
        )

        # Global arguments
        parser.add_argument(
            '-h', '--help',
            action='store_true',
            help=argparse.SUPPRESS,
        )

        parser.add_argument('--version',
                            action='version',
                            version=novaclient.__version__)

        parser.add_argument(
            '--debug',
            default=False,
            action='store_true',
            help=_("Print debugging output"))

        parser.add_argument(
            '--os-cache',
            default=strutils.bool_from_string(
                cliutils.env('OS_CACHE', default=False), True),
            action='store_true',
            help=_("Use the auth token cache. Defaults to False if "
                   "env[OS_CACHE] is not set."))

        parser.add_argument(
            '--timings',
            default=False,
            action='store_true',
            help=_("Print call timing info"))

        parser.add_argument(
            '--os-auth-token',
            default=cliutils.env('OS_AUTH_TOKEN'),
            help='Defaults to env[OS_AUTH_TOKEN]')

        parser.add_argument(
            '--os_username',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os_password',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-tenant-name',
            metavar='<auth-tenant-name>',
            default=cliutils.env('OS_TENANT_NAME', 'NOVA_PROJECT_ID'),
            help=_('Defaults to env[OS_TENANT_NAME].'))
        parser.add_argument(
            '--os_tenant_name',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-tenant-id',
            metavar='<auth-tenant-id>',
            default=cliutils.env('OS_TENANT_ID'),
            help=_('Defaults to env[OS_TENANT_ID].'))

        parser.add_argument(
            '--os_auth_url',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-region-name',
            metavar='<region-name>',
            default=cliutils.env('OS_REGION_NAME', 'NOVA_REGION_NAME'),
            help=_('Defaults to env[OS_REGION_NAME].'))
        parser.add_argument(
            '--os_region_name',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-auth-system',
            metavar='<auth-system>',
            default=cliutils.env('OS_AUTH_SYSTEM'),
            help='Defaults to env[OS_AUTH_SYSTEM].')
        parser.add_argument(
            '--os_auth_system',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--service-type',
            metavar='<service-type>',
            help=_('Defaults to compute for most actions'))
        parser.add_argument(
            '--service_type',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--service-name',
            metavar='<service-name>',
            default=cliutils.env('NOVA_SERVICE_NAME'),
            help=_('Defaults to env[NOVA_SERVICE_NAME]'))
        parser.add_argument(
            '--service_name',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--volume-service-name',
            metavar='<volume-service-name>',
            default=cliutils.env('NOVA_VOLUME_SERVICE_NAME'),
            help=_('Defaults to env[NOVA_VOLUME_SERVICE_NAME]'))
        parser.add_argument(
            '--volume_service_name',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-endpoint-type',
            metavar='<endpoint-type>',
            dest='endpoint_type',
            default=cliutils.env(
                'NOVA_ENDPOINT_TYPE',
                default=cliutils.env(
                    'OS_ENDPOINT_TYPE',
                    default=DEFAULT_NOVA_ENDPOINT_TYPE)),
            help=_('Defaults to env[NOVA_ENDPOINT_TYPE], '
                   'env[OS_ENDPOINT_TYPE] or ') +
                 DEFAULT_NOVA_ENDPOINT_TYPE + '.')

        parser.add_argument(
            '--endpoint-type',
            help=argparse.SUPPRESS)
        # NOTE(dtroyer): We can't add --endpoint_type here due to argparse
        #                thinking usage-list --end is ambiguous; but it
        #                works fine with only --endpoint-type present
        #                Go figure.  I'm leaving this here for doc purposes.
        # parser.add_argument('--endpoint_type',
        #     help=argparse.SUPPRESS)

        parser.add_argument(
            '--os-compute-api-version',
            metavar='<compute-api-ver>',
            default=cliutils.env('OS_COMPUTE_API_VERSION',
                                 default=DEFAULT_OS_COMPUTE_API_VERSION),
            help=_('Accepts number of API version, '
                   'defaults to env[OS_COMPUTE_API_VERSION].'))
        parser.add_argument(
            '--os_compute_api_version',
            help=argparse.SUPPRESS)

        parser.add_argument(
            '--bypass-url',
            metavar='<bypass-url>',
            dest='bypass_url',
            default=cliutils.env('NOVACLIENT_BYPASS_URL'),
            help="Use this API endpoint instead of the Service Catalog. "
                 "Defaults to env[NOVACLIENT_BYPASS_URL]")
        parser.add_argument('--bypass_url',
                            help=argparse.SUPPRESS)

        # The auth-system-plugins might require some extra options
        novaclient.auth_plugin.load_auth_system_opts(parser)

        self._append_global_identity_args(parser)

        return parser

    def get_subcommand_parser(self, version):
        parser = self.get_base_parser()

        self.subcommands = {}
        subparsers = parser.add_subparsers(metavar='<subcommand>')

        try:
            actions_module = {
                '1.1': shell_v2,
                '2': shell_v2,
                '3': shell_v2,
            }[version]
        except KeyError:
            actions_module = shell_v2

        self._find_actions(subparsers, actions_module)
        self._find_actions(subparsers, self)

        for extension in self.extensions:
            self._find_actions(subparsers, extension.module)

        self._add_bash_completion_subparser(subparsers)

        return parser

    # TODO(lyj): Delete this method after heat patched to use
    #            client.discover_extensions
    def _discover_extensions(self, version):
        return client.discover_extensions(version)

    def _add_bash_completion_subparser(self, subparsers):
        subparser = subparsers.add_parser(
            'bash_completion',
            add_help=False,
            formatter_class=OpenStackHelpFormatter
        )
        self.subcommands['bash_completion'] = subparser
        subparser.set_defaults(func=self.do_bash_completion)

    def _find_actions(self, subparsers, actions_module):
        for attr in (a for a in dir(actions_module) if a.startswith('do_')):
            # I prefer to be hyphen-separated instead of underscores.
            command = attr[3:].replace('_', '-')
            callback = getattr(actions_module, attr)
            desc = callback.__doc__ or ''
            action_help = desc.strip()
            arguments = getattr(callback, 'arguments', [])

            subparser = subparsers.add_parser(
                command,
                help=action_help,
                description=desc,
                add_help=False,
                formatter_class=OpenStackHelpFormatter)
            subparser.add_argument(
                '-h', '--help',
                action='help',
                help=argparse.SUPPRESS,
            )
            self.subcommands[command] = subparser
            for (args, kwargs) in arguments:
                subparser.add_argument(*args, **kwargs)
            subparser.set_defaults(func=callback)

    def setup_debugging(self, debug):
        if not debug:
            return

        streamformat = "%(levelname)s (%(module)s:%(lineno)d) %(message)s"
        # Set up the root logger to debug so that the submodules can
        # print debug messages
        logging.basicConfig(level=logging.DEBUG,
                            format=streamformat)

    def _get_keystone_auth(self, session, auth_url, **kwargs):
        auth_token = kwargs.pop('auth_token', None)
        if auth_token:
            return token.Token(auth_url, auth_token, **kwargs)
        else:
            return password.Password(
                auth_url,
                username=kwargs.pop('username'),
                user_id=kwargs.pop('user_id'),
                password=kwargs.pop('password'),
                user_domain_id=kwargs.pop('user_domain_id'),
                user_domain_name=kwargs.pop('user_domain_name'),
                **kwargs)

    def main(self, argv):
        # Parse args once to find version and debug settings
        parser = self.get_base_parser()
        (options, args) = parser.parse_known_args(argv)
        self.setup_debugging(options.debug)

        # Discover available auth plugins
        novaclient.auth_plugin.discover_auth_systems()

        # build available subcommands based on version
        self.extensions = self._discover_extensions(
            options.os_compute_api_version)
        self._run_extension_hooks('__pre_parse_args__')

        # NOTE(dtroyer): Hackery to handle --endpoint_type due to argparse
        #                thinking usage-list --end is ambiguous; but it
        #                works fine with only --endpoint-type present
        #                Go figure.
        if '--endpoint_type' in argv:
            spot = argv.index('--endpoint_type')
            argv[spot] = '--endpoint-type'

        subcommand_parser = self.get_subcommand_parser(
            options.os_compute_api_version)
        self.parser = subcommand_parser

        if options.help or not argv:
            subcommand_parser.print_help()
            return 0

        args = subcommand_parser.parse_args(argv)
        self._run_extension_hooks('__post_parse_args__', args)

        # Short-circuit and deal with help right away.
        if args.func == self.do_help:
            self.do_help(args)
            return 0
        elif args.func == self.do_bash_completion:
            self.do_bash_completion(args)
            return 0

        os_username = args.os_username
        os_user_id = args.os_user_id
        os_password = None  # Fetched and set later as needed
        os_tenant_name = args.os_tenant_name
        os_tenant_id = args.os_tenant_id
        os_auth_url = args.os_auth_url
        os_region_name = args.os_region_name
        os_auth_system = args.os_auth_system
        endpoint_type = args.endpoint_type
        insecure = args.insecure
        service_type = args.service_type
        service_name = args.service_name
        volume_service_name = args.volume_service_name
        bypass_url = args.bypass_url
        os_cache = args.os_cache
        cacert = args.os_cacert
        timeout = args.timeout

        keystone_session = None
        keystone_auth = None

        # We may have either, both or none of these.
        # If we have both, we don't need USERNAME, PASSWORD etc.
        # Fill in the blanks from the SecretsHelper if possible.
        # Finally, authenticate unless we have both.
        # Note if we don't auth we probably don't have a tenant ID so we can't
        # cache the token.
        auth_token = args.os_auth_token if args.os_auth_token else None
        management_url = bypass_url if bypass_url else None

        if os_auth_system and os_auth_system != "keystone":
            auth_plugin = novaclient.auth_plugin.load_plugin(os_auth_system)
        else:
            auth_plugin = None

        if not endpoint_type:
            endpoint_type = DEFAULT_NOVA_ENDPOINT_TYPE

        # This allow users to use endpoint_type as (internal, public or admin)
        # just like other openstack clients (glance, cinder etc)
        if endpoint_type in ['internal', 'public', 'admin']:
            endpoint_type += 'URL'

        if not service_type:
            service_type = (cliutils.get_service_type(args.func) or
                            DEFAULT_NOVA_SERVICE_TYPE)

        # If we have an auth token but no management_url, we must auth anyway.
        # Expired tokens are handled by client.py:_cs_request
        must_auth = not (cliutils.isunauthenticated(args.func)
                         or (auth_token and management_url))

        # Do not use Keystone session for cases with no session support. The
        # presence of auth_plugin means os_auth_system is present and is not
        # keystone.
        use_session = True
        if auth_plugin or bypass_url or os_cache or volume_service_name:
            use_session = False

        # FIXME(usrleon): Here should be restrict for project id same as
        # for os_username or os_password but for compatibility it is not.
        if must_auth:
            if auth_plugin:
                auth_plugin.parse_opts(args)

            if not auth_plugin or not auth_plugin.opts:
                if not os_username and not os_user_id:
                    raise exc.CommandError(
                        _("You must provide a username "
                          "or user id via --os-username, --os-user-id, "
                          "env[OS_USERNAME] or env[OS_USER_ID]"))

            if not any([args.os_tenant_name, args.os_tenant_id,
                        args.os_project_id, args.os_project_name]):
                raise exc.CommandError(_("You must provide a project name or"
                                         " project id via --os-project-name,"
                                         " --os-project-id, env[OS_PROJECT_ID]"
                                         " or env[OS_PROJECT_NAME]. You may"
                                         " use os-project and os-tenant"
                                         " interchangeably."))

            if not os_auth_url:
                if os_auth_system and os_auth_system != 'keystone':
                    os_auth_url = auth_plugin.get_auth_url()

            if not os_auth_url:
                    raise exc.CommandError(
                        _("You must provide an auth url "
                          "via either --os-auth-url or env[OS_AUTH_URL] "
                          "or specify an auth_system which defines a "
                          "default url with --os-auth-system "
                          "or env[OS_AUTH_SYSTEM]"))

            project_id = args.os_project_id or args.os_tenant_id
            project_name = args.os_project_name or args.os_tenant_name
            if use_session:
                # Not using Nova auth plugin, so use keystone
                with utils.record_time(self.times, args.timings,
                                       'auth_url', args.os_auth_url):
                    keystone_session = (ksession.Session
                                        .load_from_cli_options(args))
                    keystone_auth = self._get_keystone_auth(
                        keystone_session,
                        args.os_auth_url,
                        username=args.os_username,
                        user_id=args.os_user_id,
                        user_domain_id=args.os_user_domain_id,
                        user_domain_name=args.os_user_domain_name,
                        password=args.os_password,
                        auth_token=args.os_auth_token,
                        project_id=project_id,
                        project_name=project_name,
                        project_domain_id=args.os_project_domain_id,
                        project_domain_name=args.os_project_domain_name)

        if options.os_compute_api_version:
            if not any([args.os_tenant_id, args.os_tenant_name,
                        args.os_project_id, args.os_project_name]):
                raise exc.CommandError(_("You must provide a project name or"
                                         " project id via --os-project-name,"
                                         " --os-project-id, env[OS_PROJECT_ID]"
                                         " or env[OS_PROJECT_NAME]. You may"
                                         " use os-project and os-tenant"
                                         " interchangeably."))

            if not os_auth_url:
                raise exc.CommandError(
                    _("You must provide an auth url "
                      "via either --os-auth-url or env[OS_AUTH_URL]"))

        self.cs = client.Client(
            options.os_compute_api_version,
            os_username, os_password, os_tenant_name,
            tenant_id=os_tenant_id, user_id=os_user_id,
            auth_url=os_auth_url, insecure=insecure,
            region_name=os_region_name, endpoint_type=endpoint_type,
            extensions=self.extensions, service_type=service_type,
            service_name=service_name, auth_system=os_auth_system,
            auth_plugin=auth_plugin, auth_token=auth_token,
            volume_service_name=volume_service_name,
            timings=args.timings, bypass_url=bypass_url,
            os_cache=os_cache, http_log_debug=options.debug,
            cacert=cacert, timeout=timeout,
            session=keystone_session, auth=keystone_auth)

        # Now check for the password/token of which pieces of the
        # identifying keyring key can come from the underlying client
        if must_auth:
            helper = SecretsHelper(args, self.cs.client)
            if (auth_plugin and auth_plugin.opts and
                    "os_password" not in auth_plugin.opts):
                use_pw = False
            else:
                use_pw = True

            tenant_id = helper.tenant_id
            # Allow commandline to override cache
            if not auth_token:
                auth_token = helper.auth_token
            if not management_url:
                management_url = helper.management_url
            if tenant_id and auth_token and management_url:
                self.cs.client.tenant_id = tenant_id
                self.cs.client.auth_token = auth_token
                self.cs.client.management_url = management_url
                self.cs.client.password_func = lambda: helper.password
            elif use_pw:
                # We're missing something, so auth with user/pass and save
                # the result in our helper.
                self.cs.client.password = helper.password
                self.cs.client.keyring_saver = helper

        try:
            # This does a couple of bits which are useful even if we've
            # got the token + service URL already. It exits fast in that case.
            if not cliutils.isunauthenticated(args.func):
                if not use_session:
                    # Only call authenticate() if Nova auth plugin is used.
                    # If keystone is used, authentication is handled as part
                    # of session.
                    self.cs.authenticate()
        except exc.Unauthorized:
            raise exc.CommandError(_("Invalid OpenStack Nova credentials."))
        except exc.AuthorizationFailure:
            raise exc.CommandError(_("Unable to authorize user"))

        args.func(self.cs, args)

        if args.timings:
            self._dump_timings(self.times + self.cs.get_timings())

    def _dump_timings(self, timings):
        class Tyme(object):
            def __init__(self, url, seconds):
                self.url = url
                self.seconds = seconds
        results = [Tyme(url, end - start) for url, start, end in timings]
        total = 0.0
        for tyme in results:
            total += tyme.seconds
        results.append(Tyme("Total", total))
        utils.print_list(results, ["url", "seconds"], sortby_index=None)

    def _run_extension_hooks(self, hook_type, *args, **kwargs):
        """Run hooks for all registered extensions."""
        for extension in self.extensions:
            extension.run_hooks(hook_type, *args, **kwargs)

    def do_bash_completion(self, _args):
        """
        Prints all of the commands and options to stdout so that the
        nova.bash_completion script doesn't have to hard code them.
        """
        commands = set()
        options = set()
        for sc_str, sc in self.subcommands.items():
            commands.add(sc_str)
            for option in sc._optionals._option_string_actions.keys():
                options.add(option)

        commands.remove('bash-completion')
        commands.remove('bash_completion')
        print(' '.join(commands | options))

    @cliutils.arg(
        'command',
        metavar='<subcommand>',
        nargs='?',
        help='Display help for <subcommand>')
    def do_help(self, args):
        """
        Display help about this program or one of its subcommands.
        """
        if args.command:
            if args.command in self.subcommands:
                self.subcommands[args.command].print_help()
            else:
                raise exc.CommandError(_("'%s' is not a valid subcommand") %
                                       args.command)
        else:
            self.parser.print_help()


# I'm picky about my shell help.
class OpenStackHelpFormatter(argparse.HelpFormatter):
    def __init__(self, prog, indent_increment=2, max_help_position=32,
                 width=None):
        super(OpenStackHelpFormatter, self).__init__(prog, indent_increment,
                                                     max_help_position, width)

    def start_section(self, heading):
        # Title-case the headings
        heading = '%s%s' % (heading[0].upper(), heading[1:])
        super(OpenStackHelpFormatter, self).start_section(heading)


def main():
    try:
        argv = [encodeutils.safe_decode(a) for a in sys.argv[1:]]
        OpenStackComputeShell().main(argv)

    except Exception as e:
        logger.debug(e, exc_info=1)
        details = {'name': encodeutils.safe_encode(e.__class__.__name__),
                   'msg': encodeutils.safe_encode(six.text_type(e))}
        print("ERROR (%(name)s): %(msg)s" % details,
              file=sys.stderr)
        sys.exit(1)
    except KeyboardInterrupt:
        print("... terminating nova client", file=sys.stderr)
        sys.exit(130)


if __name__ == "__main__":
    main()