glance

#!/usr/bin/env python
# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2011 OpenStack, LLC
# 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.

"""
This is the administration program for Glance. It is simply a command-line
interface for adding, modifying, and retrieving information about the images
stored in one or more Glance nodes.
"""

import functools
import gettext
import optparse
import os
import sys
import time

from urlparse import urlparse

# If ../glance/__init__.py exists, add ../ to Python search path, so that
# it will override what happens to be installed in /usr/(local/)lib/python...
possible_topdir = os.path.normpath(os.path.join(os.path.abspath(sys.argv[0]),
                                   os.pardir,
                                   os.pardir))
if os.path.exists(os.path.join(possible_topdir, 'glance', '__init__.py')):
    sys.path.insert(0, possible_topdir)

gettext.install('glance', unicode=1)

from glance import version
from glance import client as glance_client
from glance.common import exception
from glance.common import utils


SUCCESS = 0
FAILURE = 1

DEFAULT_PORT = 9292


#TODO(sirp): make more of the actions use this decorator
def catch_error(action):
    """Decorator to provide sensible default error handling for actions."""
    def wrap(func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            try:
                ret = func(*args, **kwargs)
                return SUCCESS if ret is None else ret
            except exception.NotAuthorized:
                print "Not authorized to make this request. Check "\
                      "your credentials (OS_AUTH_USER, OS_AUTH_KEY, ...)."
                return FAILURE
            except exception.ClientConfigurationError:
                raise
            except Exception, e:
                options = args[0]
                if options.debug:
                    raise
                print "Failed to %s. Got error:" % action
                pieces = unicode(e).split('\n')
                for piece in pieces:
                    print piece
                return FAILURE

        return wrapper
    return wrap


def get_image_fields_from_args(args):
    """
    Validate the set of arguments passed as field name/value pairs
    and return them as a mapping.
    """
    fields = {}
    for arg in args:
        pieces = arg.strip(',').split('=')
        if len(pieces) != 2:
            msg = ("Arguments should be in the form of field=value. "
                   "You specified %s." % arg)
            raise RuntimeError(msg)
        fields[pieces[0]] = pieces[1]

    return fields


def get_image_filters_from_args(args):
    """Build a dictionary of query filters based on the supplied args."""
    try:
        fields = get_image_fields_from_args(args)
    except RuntimeError, e:
        print e
        return FAILURE

    SUPPORTED_FILTERS = ['name', 'disk_format', 'container_format', 'status',
                         'min_ram', 'min_disk', 'size_min', 'size_max',
                         'changes-since']
    filters = {}
    for (key, value) in fields.items():
        if key not in SUPPORTED_FILTERS:
            key = 'property-%s' % (key,)
        filters[key] = value

    return filters


def print_image_formatted(client, image):
    """
    Formatted print of image metadata.

    :param client: The Glance client object
    :param image: The image metadata
    """
    print "URI: %s://%s:%s/v1/images/%s" % (
                                      client.use_ssl and "https" or "http",
                                      client.host,
                                      client.port,
                                      image['id'])
    print "Id: %s" % image['id']
    print "Public: " + (image['is_public'] and "Yes" or "No")
    print "Protected: " + (image['protected'] and "Yes" or "No")
    print "Name: %s" % image['name']
    print "Status: %s" % image['status']
    print "Size: %d" % int(image['size'])
    print "Disk format: %s" % image['disk_format']
    print "Container format: %s" % image['container_format']
    print "Minimum Ram Required (MB): %s" % image['min_ram']
    print "Minimum Disk Required (GB): %s" % image['min_disk']
    if image.get('owner'):
        print "Owner: %s" % image['owner']
    if len(image['properties']) > 0:
        for k, v in image['properties'].items():
            print "Property '%s': %s" % (k, v)


def image_add(options, args):
    """
%(prog)s add [options] <field1=value1 field2=value2 ...> [ < /path/to/image ]

Adds a new image to Glance. Specify metadata fields as arguments.

SPECIFYING IMAGE METADATA
===============================================================================

All field/value pairs are converted into a mapping that is passed
to Glance that represents the metadata for an image.

Field names of note:

id                  Optional. If not specified, an image identifier will be
                    automatically assigned.
name                Required. A name for the image.
size                Optional. Should be size in bytes of the image if
                    specified.
is_public           Optional. If specified, interpreted as a boolean value
                    and sets or unsets the image's availability to the public.
                    The default value is False.
protected           Optional. If specified, interpreted as a boolean value
                    and enables or disables deletion protection.
                    The default value is False.
disk_format         Required. Possible values are 'vhd','vmdk','raw', 'qcow2',
                    and 'ami'.
container_format    Required. Possible values are 'ovf' and 'ami'.
location            Optional. When specified, should be a readable location
                    in the form of a URI: $STORE://LOCATION. For example, if
                    the image data is stored in a file on the local
                    filesystem at /usr/share/images/some.image.tar.gz
                    you would specify:
                    location=file:///usr/share/images/some.image.tar.gz

Any other field names are considered to be custom properties so be careful
to spell field names correctly. :)

STREAMING IMAGE DATA
===============================================================================

If the location field is not specified, you can stream an image file on
the command line using standard redirection. For example:

%(prog)s add name="Ubuntu 10.04 LTS 5GB" < /tmp/images/myimage.tar.gz

EXAMPLES
===============================================================================

%(prog)s add name="My Image" disk_format=raw container_format=ovf \\
    location=http://images.ubuntu.org/images/lucid-10.04-i686.iso \\
    distro="Ubuntu 10.04 LTS"

%(prog)s add name="My Image" disk_format=raw container_format=ovf \\
    distro="Ubuntu 10.04 LTS" < /tmp/myimage.iso"""
    c = get_client(options)

    try:
        fields = get_image_fields_from_args(args)
    except RuntimeError, e:
        print e
        return FAILURE

    if 'name' not in fields.keys():
        print "Please specify a name for the image using name=VALUE"
        return FAILURE

    image_meta = {'name': fields.pop('name'),
                  'is_public': utils.bool_from_string(
                      fields.pop('is_public', False)),
                  'protected': utils.bool_from_string(
                      fields.pop('protected', False)),
                  'min_disk': fields.pop('min_disk', 0),
                  'min_ram': fields.pop('min_ram', 0),
    }

    for format in ['disk_format', 'container_format']:
        if format in fields:
            image_meta[format] = fields.pop(format)

    # Strip any args that are not supported
    unsupported_fields = ['status', 'size']
    for field in unsupported_fields:
        if field in fields.keys():
            print 'Found non-settable field %s. Removing.' % field
            fields.pop(field)

    if 'location' in fields.keys():
        image_meta['location'] = fields.pop('location')

    # We need either a location or image data/stream to add...
    image_location = image_meta.get('location')
    image_data = None
    if not image_location:
        # Grab the image data stream from stdin or redirect,
        # otherwise error out
        image_data = sys.stdin

    # Add custom attributes, which are all the arguments remaining
    image_meta['properties'] = fields

    if not options.dry_run:
        try:
            image_meta = c.add_image(image_meta, image_data)
            image_id = image_meta['id']
            print "Added new image with ID: %s" % image_id
            if options.verbose:
                print "Returned the following metadata for the new image:"
                for k, v in sorted(image_meta.items()):
                    print " %(k)30s => %(v)s" % locals()
        except exception.ClientConnectionError, e:
            host = options.host
            port = options.port
            print ("Failed to connect to the Glance API server "
                   "%(host)s:%(port)d. Is the server running?" % locals())
            if options.verbose:
                pieces = unicode(e).split('\n')
                for piece in pieces:
                    print piece
            return FAILURE
        except Exception, e:
            print "Failed to add image. Got error:"
            pieces = unicode(e).split('\n')
            for piece in pieces:
                print piece
            print ("Note: Your image metadata may still be in the registry, "
                   "but the image's status will likely be 'killed'.")
            return FAILURE
    else:
        print "Dry run. We would have done the following:"
        print "Add new image with metadata:"
        for k, v in sorted(image_meta.items()):
            print " %(k)30s => %(v)s" % locals()

    return SUCCESS


def image_update(options, args):
    """
%(prog)s update [options] <ID> <field1=value1 field2=value2 ...>

Updates an image's metadata in Glance. Specify metadata fields as arguments.

Metadata fields that are not specified in the update command will be deleted.

All field/value pairs are converted into a mapping that is passed
to Glance that represents the metadata for an image.

Field names that can be specified:

name                A name for the image.
location            The location of the image.
is_public           If specified, interpreted as a boolean value
                    and sets or unsets the image's availability to the public.
protected           If specified, interpreted as a boolean value
                    and enables or disables deletion protection for the image.
disk_format         Format of the disk image
container_format    Format of the container

All other field names are considered to be custom properties so be careful
to spell field names correctly. :)"""
    c = get_client(options)
    try:
        image_id = args.pop(0)
    except IndexError:
        print "Please specify the ID of the image you wish to update "
        print "as the first argument"
        return FAILURE

    try:
        fields = get_image_fields_from_args(args)
    except RuntimeError, e:
        print e
        return FAILURE

    image_meta = {}

    # Strip any args that are not supported
    nonmodifiable_fields = ['created_on', 'deleted_on', 'deleted',
                          'updated_on', 'size', 'status']
    for field in nonmodifiable_fields:
        if field in fields.keys():
            print 'Found non-modifiable field %s. Removing.' % field
            fields.pop(field)

    base_image_fields = ['disk_format', 'container_format', 'name',
                         'min_disk', 'min_ram', 'location', 'owner']
    for field in base_image_fields:
        fvalue = fields.pop(field, None)
        if fvalue is not None:
            image_meta[field] = fvalue

    # Have to handle "boolean" values specially...
    if 'is_public' in fields:
        image_meta['is_public'] = utils.bool_from_string(
            fields.pop('is_public'))
    if 'protected' in fields:
        image_meta['protected'] = utils.bool_from_string(
            fields.pop('protected'))

    # Add custom attributes, which are all the arguments remaining
    image_meta['properties'] = fields

    if not options.dry_run:
        try:
            image_meta = c.update_image(image_id, image_meta=image_meta)
            print "Updated image %s" % image_id

            if options.verbose:
                print "Updated image metadata for image %s:" % image_id
                print_image_formatted(c, image_meta)
        except exception.NotFound:
            print "No image with ID %s was found" % image_id
            return FAILURE
        except Exception, e:
            print "Failed to update image. Got error:"
            pieces = unicode(e).split('\n')
            for piece in pieces:
                print piece
            return FAILURE
    else:
        print "Dry run. We would have done the following:"
        print "Update existing image with metadata:"
        for k, v in sorted(image_meta.items()):
            print " %(k)30s => %(v)s" % locals()
    return SUCCESS


def image_delete(options, args):
    """
%(prog)s delete [options] <ID>

Deletes an image from Glance"""
    try:
        image_id = args.pop()
    except IndexError:
        print "Please specify the ID of the image you wish to delete "
        print "as the first argument"
        return FAILURE

    if not options.force and \
       not user_confirm("Delete image %s?" % (image_id,), default=False):
        print 'Not deleting image %s' % (image_id,)
        return FAILURE

    c = get_client(options)

    try:
        c.delete_image(image_id)
        print "Deleted image %s" % image_id
        return SUCCESS
    except exception.NotFound:
        print "No image with ID %s was found" % image_id
        return FAILURE


def image_show(options, args):
    """
%(prog)s show [options] <ID>

Shows image metadata for an image in Glance"""
    c = get_client(options)
    try:
        if len(args) > 0:
            image_id = args[0]
        else:
            print "Please specify the image identifier as the "
            print "first argument. Example: "
            print "$> glance-admin show 12345"
            return FAILURE

        image = c.get_image_meta(image_id)
        print_image_formatted(c, image)
        return SUCCESS
    except exception.NotFound:
        print "No image with ID %s was found" % image_id
        return FAILURE
    except Exception, e:
        print "Failed to show image. Got error:"
        pieces = unicode(e).split('\n')
        for piece in pieces:
            print piece
        return FAILURE


def _images_index(client, filters, limit, print_header=False, **kwargs):
    """Driver function for images_index"""
    parameters = {
        "filters": filters,
        "limit": limit,
    }

    optional_kwargs = ['marker', 'sort_key', 'sort_dir']
    for kwarg in optional_kwargs:
        if kwarg in kwargs:
            parameters[kwarg] = kwargs[kwarg]

    images = client.get_images(**parameters)

    if not images:
        return SUCCESS

    pretty_table = utils.PrettyTable()
    pretty_table.add_column(36, label="ID")
    pretty_table.add_column(30, label="Name")
    pretty_table.add_column(20, label="Disk Format")
    pretty_table.add_column(20, label="Container Format")
    pretty_table.add_column(14, label="Size", just="r")

    if print_header:
        print pretty_table.make_header()

    for image in images:
        print pretty_table.make_row(image['id'],
                                    image['name'],
                                    image['disk_format'],
                                    image['container_format'],
                                    image['size'])

    if not options.force and len(images) == limit and \
       not user_confirm("Fetch next page?", True):
        return SUCCESS

    parameters['marker'] = images[-1]['id']
    return _images_index(client, **parameters)


@catch_error('show index')
def images_index(options, args):
    """
%(prog)s index [options] <field1=value1 field2=value2 ...>

Returns basic information for all public images
a Glance server knows about. Provided fields are
handled as query filters. Supported filters
include 'name', 'disk_format', 'container_format',
'status', 'size_min', 'size_max' and 'changes-since.'
Any extra fields are treated as image metadata properties"""
    client = get_client(options)
    filters = get_image_filters_from_args(args)
    limit = options.limit
    marker = options.marker
    sort_key = options.sort_key
    sort_dir = options.sort_dir

    return _images_index(client,
                         filters,
                         limit,
                         marker=marker,
                         sort_key=sort_key,
                         sort_dir=sort_dir,
                         print_header=True)


def _images_details(client, filters, limit, print_header=False, **kwargs):
    """Driver function for images_details"""
    parameters = {
        "filters": filters,
        "limit": limit,
    }

    optional_kwargs = ['marker', 'sort_key', 'sort_dir']
    for kwarg in optional_kwargs:
        if kwarg in kwargs:
            parameters[kwarg] = kwargs[kwarg]

    images = client.get_images_detailed(**parameters)

    if len(images) == 0:
        return SUCCESS

    if print_header:
        print "=" * 80

    for image in images:
        print_image_formatted(client, image)
        print "=" * 80

    if not options.force and len(images) == limit and \
       not user_confirm("Fetch next page?", True):
        return SUCCESS

    parameters["marker"] = images[-1]['id']
    return _images_details(client, **parameters)


@catch_error('show details')
def images_details(options, args):
    """
%(prog)s details [options]

Returns detailed information for all public images
a Glance server knows about. Provided fields are
handled as query filters. Supported filters
include 'name', 'disk_format', 'container_format',
'status', 'size_min', 'size_max' and 'changes-since.'
Any extra fields are treated as image metadata properties"""
    client = get_client(options)
    filters = get_image_filters_from_args(args)
    limit = options.limit
    marker = options.marker
    sort_key = options.sort_key
    sort_dir = options.sort_dir

    return _images_details(client,
                           filters,
                           limit,
                           marker=marker,
                           sort_key=sort_key,
                           sort_dir=sort_dir,
                           print_header=True)


def images_clear(options, args):
    """
%(prog)s clear [options]

Deletes all images from a Glance server"""
    if not options.force and \
       not user_confirm("Delete all images?", default=False):
        print 'Not deleting any images'
        return FAILURE

    c = get_client(options)
    images = c.get_images()
    for image in images:
        if options.verbose:
            print 'Deleting image %s "%s" ...' % (image['id'], image['name']),
        try:
            c.delete_image(image['id'])
            if options.verbose:
                print 'done'
        except Exception, e:
            print 'Failed to delete image %s' % image['id']
            print e
            return FAILURE
    return SUCCESS


@catch_error('show image members')
def image_members(options, args):
    """
%(prog)s image-members [options] <ID>

Displays a list of members with which an image is shared"""
    try:
        image_id = args.pop()
    except IndexError:
        print "Please specify the ID of the image as the first argument"
        return FAILURE

    c = get_client(options)

    members = c.get_image_members(image_id)
    sharers = 0
    # Output the list of members
    for memb in members:
        can_share = ''
        if 'can_share' in memb and memb['can_share']:
            can_share = ' *'
            sharers += 1
        print "%s%s" % (memb['member_id'], can_share)

    # Emit a footnote
    if sharers > 0:
        print "\n(*: Can share image)"


@catch_error('show member images')
def member_images(options, args):
    """
%(prog)s member-images [options] <MEMBER>

Displays a list of images shared with a given member"""
    try:
        member_id = args.pop()
    except IndexError:
        print "Please specify the ID of the member as the first argument"
        return FAILURE

    c = get_client(options)

    try:
        members = c.get_member_images(member_id)
    except exception.NotFound:
        print "No images shared with member %s" % member_id
        return SUCCESS

    sharers = 0
    # Output the list of images
    for memb in members:
        can_share = ''
        if 'can_share' in memb and memb['can_share']:
            can_share = ' *'
            sharers += 1
        print "%s%s" % (memb['image_id'], can_share)

    # Emit a footnote
    if sharers > 0:
        print "\n(*: Can share image)"


@catch_error('update image members')
def members_replace(options, args):
    """
%(prog)s members-replace [options] <ID> <MEMBER>

Replaces the members of the image <ID> to be solely <MEMBER>.  If the
"--can-share" option is given, <MEMBER> will be able to further share
the image."""
    try:
        member_id = args.pop()
        image_id = args.pop()
    except IndexError:
        print "Please specify the image ID and the member name"
        return FAILURE

    c = get_client(options)

    # Update members
    if not options.dry_run:
        c.replace_members(image_id, dict(member_id=member_id,
                                         can_share=options.can_share))
    else:
        print "Dry run. We would have done the following:"
        print ('Replace members of image %(image_id)s with "%(member_id)s"'
               % locals())
        if options.can_share:
            print "New member would have been able to further share image."


@catch_error('add image member')
def member_add(options, args):
    """
%(prog)s member-add [options] <ID> <MEMBER>

Adds the member <MEMBER> to the image <ID>.  If the "--can-share"
option is given, <MEMBER> will be able to further share the image."""
    try:
        member_id = args.pop()
        image_id = args.pop()
    except IndexError:
        print "Please specify the image ID and the member name"
        return FAILURE

    c = get_client(options)

    # Replace members
    if not options.dry_run:
        c.add_member(image_id, member_id, options.can_share)
    else:
        print "Dry run. We would have done the following:"
        print ('Add "%(member_id)s" to membership of image %(image_id)s'
               % locals())
        if options.can_share:
            print "New member would have been able to further share image."


@catch_error('delete image member')
def member_delete(options, args):
    """
%(prog)s member-delete [options] <ID> <MEMBER>

Deletes the specified member of the image <ID>."""
    try:
        member_id = args.pop()
        image_id = args.pop()
    except IndexError:
        print "Please specify the image ID and the member name"
        return FAILURE

    c = get_client(options)

    # Delete member
    if not options.dry_run:
        c.delete_member(image_id, member_id)
    else:
        print "Dry run. We would have done the following:"
        print ('Remove "%(member_id)s" from the member list of image '
               '"%(image_id)s"' % locals())


def get_client(options):
    """
    Returns a new client object to a Glance server
    specified by the --host and --port options
    supplied to the CLI
    """

    if options.auth_url or os.getenv('OS_AUTH_URL'):
        force_strategy = 'keystone'
    else:
        force_strategy = None

    creds = dict(username=options.username or \
                         os.getenv('OS_AUTH_USER', os.getenv('OS_USERNAME')),
                 password=options.password or \
                         os.getenv('OS_AUTH_KEY', os.getenv('OS_PASSWORD')),
                 tenant=options.tenant or \
                         os.getenv('OS_AUTH_TENANT',
                                 os.getenv('OS_TENANT_NAME')),
                 auth_url=options.auth_url or os.getenv('OS_AUTH_URL'),
                 strategy=force_strategy or options.auth_strategy or \
                          os.getenv('OS_AUTH_STRATEGY', 'noauth'))

    if creds['strategy'] == 'keystone' and not creds['auth_url']:
        msg = ("--auth_url option or OS_AUTH_URL environment variable "
               "required when keystone authentication strategy is enabled\n")
        raise exception.ClientConfigurationError(msg)

    use_ssl = (options.use_ssl or (
        creds['auth_url'] is not None and
        creds['auth_url'].find('https') != -1))

    return glance_client.Client(host=options.host, port=options.port,
                                use_ssl=use_ssl,
                                auth_tok=options.auth_token or \
                                        os.getenv('OS_TOKEN'),
                                creds=creds, insecure=options.insecure)


def create_options(parser):
    """
    Sets up the CLI and config-file options that may be
    parsed and program commands.

    :param parser: The option parser
    """
    parser.add_option('-v', '--verbose', default=False, action="store_true",
                      help="Print more verbose output")
    parser.add_option('-d', '--debug', default=False, action="store_true",
                      help="Print more verbose output")
    parser.add_option('-H', '--host', metavar="ADDRESS", default="0.0.0.0",
                      help="Address of Glance API host. "
                           "Default: %default")
    parser.add_option('-p', '--port', dest="port", metavar="PORT",
                      type=int, default=DEFAULT_PORT,
                      help="Port the Glance API host listens on. "
                           "Default: %default")
    parser.add_option('-U', '--url', metavar="URL", default=None,
                      help="URL of Glance service. This option can be used "
                           "to specify the hostname, port and protocol "
                           "(http/https) of the glance server, for example "
                           "-U https://localhost:" + str(DEFAULT_PORT) +
                           "/v1 Default: None")
    parser.add_option('-k', '--insecure', dest="insecure",
                      default=False, action="store_true",
                      help="Explicitly allow glance to perform \"insecure\" "
                      "SSL (https) requests. The server's certificate will "
                      "not be verified against any certificate authorities. "
                      "This option should be used with caution.")
    parser.add_option('-A', '--auth_token', dest="auth_token",
                      metavar="TOKEN", default=None,
                      help="Authentication token to use to identify the "
                           "client to the glance server")
    parser.add_option('-I', '--username', dest="username",
                      metavar="USER", default=None,
                      help="User name used to acquire an authentication token")
    parser.add_option('-K', '--password', dest="password",
                      metavar="PASSWORD", default=None,
                      help="Password used to acquire an authentication token")
    parser.add_option('-T', '--tenant', dest="tenant",
                      metavar="TENANT", default=None,
                      help="Tenant name")
    parser.add_option('-N', '--auth_url', dest="auth_url",
                      metavar="AUTH_URL", default=None,
                      help="Authentication URL")
    parser.add_option('-S', '--auth_strategy', dest="auth_strategy",
                      metavar="STRATEGY", default=None,
                      help="Authentication strategy (keystone or noauth)")
    parser.add_option('--limit', dest="limit", metavar="LIMIT", default=10,
                      type="int", help="Page size to use while "
                                       "requesting image metadata")
    parser.add_option('--marker', dest="marker", metavar="MARKER",
                      default=None, help="Image index after which to "
                                         "begin pagination")
    parser.add_option('--sort_key', dest="sort_key", metavar="KEY",
                      help="Sort results by this image attribute.")
    parser.add_option('--sort_dir', dest="sort_dir", metavar="[desc|asc]",
                      help="Sort results in this direction.")
    parser.add_option('-f', '--force', dest="force",
                      default=False, action="store_true",
                      help="Prevent select actions from requesting "
                           "user confirmation")
    parser.add_option('--dry-run', default=False, action="store_true",
                      help="Don't actually execute the command, just print "
                           "output showing what WOULD happen.")
    parser.add_option('--can-share', default=False, action="store_true",
                      help="Allow member to further share image.")


def parse_options(parser, cli_args):
    """
    Returns the parsed CLI options, command to run and its arguments, merged
    with any same-named options found in a configuration file

    :param parser: The option parser
    """
    if not cli_args:
        cli_args.append('-h')  # Show options in usage output...

    (options, args) = parser.parse_args(cli_args)
    if options.url is not None:
        u = urlparse(options.url)
        options.port = u.port
        options.host = u.hostname

    options.use_ssl = (options.url is not None and u.scheme == 'https')

    # HACK(sirp): Make the parser available to the print_help method
    # print_help is a command, so it only accepts (options, args); we could
    # one-off have it take (parser, options, args), however, for now, I think
    # this little hack will suffice
    options.__parser = parser

    if not args:
        parser.print_usage()
        sys.exit(0)

    command_name = args.pop(0)
    command = lookup_command(parser, command_name)

    return (options, command, args)


def print_help(options, args):
    """
    Print help specific to a command
    """
    if len(args) != 1:
        sys.exit("Please specify a command")

    parser = options.__parser
    command_name = args.pop()
    command = lookup_command(parser, command_name)

    print command.__doc__ % {'prog': os.path.basename(sys.argv[0])}


def lookup_command(parser, command_name):
    BASE_COMMANDS = {'help': print_help}

    IMAGE_COMMANDS = {
                'add': image_add,
                'update': image_update,
                'delete': image_delete,
                'index': images_index,
                'details': images_details,
                'show': image_show,
                'clear': images_clear}

    MEMBER_COMMANDS = {
                'image-members': image_members,
                'member-images': member_images,
                'members-replace': members_replace,
                'member-add': member_add,
                'member-delete': member_delete}

    commands = {}
    for command_set in (BASE_COMMANDS, IMAGE_COMMANDS,
                        MEMBER_COMMANDS):
        commands.update(command_set)

    try:
        command = commands[command_name]
    except KeyError:
        parser.print_usage()
        sys.exit("Unknown command: %s" % command_name)

    return command


def user_confirm(prompt, default=False):
    """
    Yes/No question dialog with user.

    :param prompt: question/statement to present to user (string)
    :param default: boolean value to return if empty string
                    is received as response to prompt

    """
    if default:
        prompt_default = "[Y/n]"
    else:
        prompt_default = "[y/N]"

    answer = raw_input("%s %s " % (prompt, prompt_default))

    if answer == "":
        return default
    else:
        return answer.lower() in ("yes", "y")


if __name__ == '__main__':
    usage = """
%prog <command> [options] [args]

Commands:

    help <command>  Output help for one of the commands below

    add             Adds a new image to Glance

    update          Updates an image's metadata in Glance

    delete          Deletes an image from Glance

    index           Return brief information about images in Glance

    details         Return detailed information about images in
                    Glance

    show            Show detailed information about an image in
                    Glance

    clear           Removes all images and metadata from Glance


Member Commands:

    image-members    List members an image is shared with

    member-images    List images shared with a member

    member-add       Grants a member access to an image

    member-delete    Revokes a member's access to an image

    members-replace  Replaces all membership for an image
"""

    oparser = optparse.OptionParser(version='%%prog %s'
                                    % version.version_string(),
                                    usage=usage.strip())
    create_options(oparser)
    (options, command, args) = parse_options(oparser, sys.argv[1:])

    try:
        start_time = time.time()
        result = command(options, args)
        end_time = time.time()
        if options.verbose:
            print "Completed in %-0.4f sec." % (end_time - start_time)
        sys.exit(result)
    except (RuntimeError,
            NotImplementedError,
            exception.ClientConfigurationError), e:
        oparser.print_usage()
        print >> sys.stderr, "ERROR: ", e
        sys.exit(1)