[1/3] backup: QEMU Backup Tool

qemu-backup will be a command-line tool for performing full and
incremental disk backups on running VMs. It is intended as a
reference implementation for management stack and backup developers
to see QEMU's backup features in action. The tool writes details of
guest in a configuration file and the data is retrieved from the file
while creating a backup. The location of config file can be set as an
environment variable QEMU_BACKUP_CONFIG. The usage is as follows:

Add a guest
python qemu-backup.py guest add --guest <guest_name> --qmp <socket_path>

Add a drive for backup in a specified guest
python qemu-backup.py drive add --guest <guest_name> --id <drive_id> [--target <target_file_path>]

Create backup of the added drives:
python qemu-backup.py backup --guest <guest_name>

List all guest configs in configuration file:
python qemu-backup.py guest list

Restore operation
python qemu-backup.py restore --guest <guest-name>

Remove a guest
python qemu-backup.py guest remove --guest <guest_name>

Signed-off-by: Ishani Chugh <chugh.ishani@research.iiit.ac.in>
---
 contrib/backup/qemu-backup.py | 334 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 334 insertions(+)
 create mode 100644 contrib/backup/qemu-backup.py

On Mon, Aug 21, 2017 at 04:40:37PM +0530, Ishani Chugh wrote:
> qemu-backup will be a command-line tool for performing full and
> incremental disk backups on running VMs. It is intended as a
> reference implementation for management stack and backup developers
> to see QEMU's backup features in action. The tool writes details of
> guest in a configuration file and the data is retrieved from the file
> while creating a backup. The location of config file can be set as an
> environment variable QEMU_BACKUP_CONFIG. The usage is as follows:
> 
> Add a guest
> python qemu-backup.py guest add --guest <guest_name> --qmp <socket_path>
> 
> Add a drive for backup in a specified guest
> python qemu-backup.py drive add --guest <guest_name> --id <drive_id> [--target <target_file_path>]
> 
> Create backup of the added drives:
> python qemu-backup.py backup --guest <guest_name>
> 
> List all guest configs in configuration file:
> python qemu-backup.py guest list
> 
> Restore operation
> python qemu-backup.py restore --guest <guest-name>
> 
> Remove a guest
> python qemu-backup.py guest remove --guest <guest_name>
> 
> Signed-off-by: Ishani Chugh <chugh.ishani@research.iiit.ac.in>
> ---
>  contrib/backup/qemu-backup.py | 334 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 334 insertions(+)
>  create mode 100644 contrib/backup/qemu-backup.py
> 
> diff --git a/contrib/backup/qemu-backup.py b/contrib/backup/qemu-backup.py
> new file mode 100644
> index 0000000..08570f7
> --- /dev/null
> +++ b/contrib/backup/qemu-backup.py
> @@ -0,0 +1,334 @@
> +#!/usr/bin/python
> +# -*- coding: utf-8 -*-
> +#
> +# Copyright (C) 2017 Ishani Chugh <chugh.ishani@research.iiit.ac.in>
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +#
> +
> +"""
> +This file is an implementation of backup tool
> +"""
> +from __future__ import print_function
> +from argparse import ArgumentParser
> +import os
> +import errno
> +from socket import error as socket_error
> +try:
> +    import configparser
> +except ImportError:
> +    import ConfigParser as configparser
> +import sys
> +sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..',
> +                             'scripts', 'qmp'))
> +from qmp import QEMUMonitorProtocol
> +
> +
> +class BackupTool(object):
> +    """BackupTool Class"""
> +    def __init__(self, config_file=os.path.expanduser('~') +
> +                 '/.config/qemu/qemu-backup-config'):
> +        if "QEMU_BACKUP_CONFIG" in os.environ:
> +            self.config_file = os.environ["QEMU_BACKUP_CONFIG"]
> +        else:
> +            self.config_file = config_file
> +            try:
> +                if not os.path.isdir(os.path.dirname(self.config_file)):
> +                    os.makedirs(os.path.dirname(self.config_file))
> +            except:
> +                print("Cannot create config directory", file=sys.stderr)
> +                sys.exit(1)
> +        self.config = configparser.ConfigParser()
> +        self.config.read(self.config_file)
> +
> +    def write_config(self):
> +        """
> +        Writes configuration to ini file.
> +        """
> +        config_file = open(self.config_file+".tmp", 'w')
> +        self.config.write(config_file)
> +        config_file.flush()
> +        os.fsync(config_file.fileno())
> +        config_file.close()
> +        os.rename(self.config_file+".tmp", self.config_file)
> +
> +    def get_socket_address(self, socket_address):
> +        """
> +        Return Socket address in form of string or tuple
> +        """
> +        if socket_address.startswith('tcp'):
> +            return (socket_address.split(':')[1],
> +                    int(socket_address.split(':')[2]))
> +        return socket_address.split(':', 2)[1]
> +
> +    def _full_backup(self, guest_name):
> +        """
> +        Performs full backup of guest
> +        """
> +        if guest_name not in self.config.sections():
> +            print("Cannot find specified guest", file=sys.stderr)
> +            sys.exit(1)
> +
> +        self.verify_guest_running(guest_name)
> +        connection = QEMUMonitorProtocol(
> +                                         self.get_socket_address(
> +                                             self.config[guest_name]['qmp']))
> +        connection.connect()
> +        cmd = {"execute": "transaction", "arguments": {"actions": []}}
> +        drive_list = []
> +        for key in self.config[guest_name]:
> +            if key.startswith("drive_"):
> +                drive = key[len('drive_'):]
> +                drive_list.append(drive)
> +                target = self.config[guest_name][key]
> +                sub_cmd = {"type": "drive-backup", "data": {"device": drive,
> +                                                            "target": target,
> +                                                            "sync": "full"}}
> +                cmd['arguments']['actions'].append(sub_cmd)
> +        qmp_return = connection.cmd_obj(cmd)
> +        if 'error' in qmp_return:
> +            print(qmp_return['error']['desc'], file=sys.stderr)
> +            sys.exit(1)
> +        print("Backup Started")
> +        while len(drive_list) != 0:
> +            event = connection.pull_event(wait=True)
> +            if event['event'] == 'SHUTDOWN':
> +                print("The guest was SHUT DOWN", file=sys.stderr)
> +                sys.exit(1)
> +
> +            if event['event'] == 'RESET':
> +                print("The guest was Rebooted", file=sys.stderr)
> +                sys.exit(1)
> +
> +            if event['data']['device'] in drive_list and \
> +                    event['data']['type'] == 'backup':

At this point the event[] dict might be a non-BLOCK_JOB_* event.
Therefore event['data']['device'] will raise a KeyError exception.

You must check event['event'] before assuming it contains certain
fields.

> +                if event['event'] == 'BLOCK_JOB_COMPLETED':
> +                    print("*"+event['data']['device'])
> +                    drive_list.remove(event['data']['device'])
> +                elif event['event'] == 'BLOCK_JOB_ERROR':
> +                    print("Cannot Complete Backup", file=sys.stderr)
> +                    sys.exit(1)
> +        print("Backup Complete")
> +
> +    def _drive_add(self, drive_id, guest_name, target=None):
> +        """
> +        Adds drive for backup
> +        """
> +        if target is None:
> +            target = os.path.abspath(drive_id)
> +
> +        if os.path.isdir(os.path.dirname(target)) is False:
> +            print("Cannot find target directory", file=sys.stderr)
> +            sys.exit(1)
> +
> +        if guest_name not in self.config.sections():
> +            print("Cannot find specified guest", file=sys.stderr)
> +            sys.exit(1)
> +
> +        if "drive_"+drive_id in self.config[guest_name]:
> +            print("Drive already marked for backup", file=sys.stderr)
> +            sys.exit(1)
> +
> +        self.verify_guest_running(guest_name)
> +
> +        connection = QEMUMonitorProtocol(
> +                                         self.get_socket_address(
> +                                             self.config[guest_name]['qmp']))
> +        connection.connect()
> +        cmd = {'execute': 'query-block'}
> +        returned_json = connection.cmd_obj(cmd)
> +        device_present = False
> +        for device in returned_json['return']:
> +            if device['device'] == drive_id:
> +                device_present = True
> +                break
> +
> +        if not device_present:
> +            print("No such drive in guest", file=sys.stderr)
> +            sys.exit(1)
> +
> +        drive_id = "drive_" + drive_id
> +        for d_id in self.config[guest_name]:
> +            if self.config[guest_name][d_id] == target:
> +                print("Please choose different target", file=sys.stderr)
> +                sys.exit(1)
> +        self.config.set(guest_name, drive_id, target)
> +        self.write_config()
> +        print("Successfully Added Drive")
> +
> +    def verify_guest_running(self, guest_name):
> +        """
> +        Checks whether specified guest is running or not
> +        """
> +        socket_address = self.config.get(guest_name, 'qmp')
> +        try:
> +            connection = QEMUMonitorProtocol(self.get_socket_address(
> +                                             socket_address))
> +            connection.connect()
> +        except socket_error:
> +            if socket_error.errno != errno.ECONNREFUSED:
> +                print("Connection to guest refused", file=sys.stderr)
> +                sys.exit(1)
> +
> +    def _guest_add(self, guest_name, socket_address):
> +        """
> +        Adds a guest to the config file
> +        """
> +        if guest_name in self.config.sections():
> +            print("ID already exists. Please choose a different guestname",
> +                  file=sys.stderr)
> +            sys.exit(1)
> +        self.config[guest_name] = {'qmp': socket_address}
> +        self.verify_guest_running(guest_name)
> +        self.write_config()
> +        print("Successfully Added Guest")
> +
> +    def _guest_remove(self, guest_name):
> +        """
> +        Removes a guest from config file
> +        """
> +        if guest_name not in self.config.sections():
> +            print("Guest Not present", file=sys.stderr)
> +            sys.exit(1)
> +        self.config.remove_section(guest_name)
> +        print("Guest successfully deleted")
> +
> +    def _restore(self, guest_name):
> +        """
> +        Prints Steps to perform restore operation
> +        """
> +        if guest_name not in self.config.sections():
> +            print("Cannot find specified guest", file=sys.stderr)
> +            sys.exit(1)
> +
> +        self.verify_guest_running(guest_name)
> +        connection = QEMUMonitorProtocol(
> +                                         self.get_socket_address(
> +                                             self.config[guest_name]['qmp']))
> +        connection.connect()
> +        print("To perform restore, replace:")
> +        for key in self.config[guest_name]:
> +            if key.startswith("drive_"):
> +                drive = key[len('drive_'):]
> +                target = self.config[guest_name][key]
> +                cmd = {'execute': 'query-block'}
> +                returned_json = connection.cmd_obj(cmd)
> +                device_present = False
> +                for device in returned_json['return']:
> +                    if device['device'] == drive:
> +                        device_present = True
> +                        location = device['inserted']['image']['filename']
> +                        print(location+" By "+target)

I suggest print('Replace ' + location + ' with ' + target) for a
slightly clearer message.

> +
> +                if not device_present:
> +                    print("No such drive in guest", file=sys.stderr)
> +                    sys.exit(1)

Since the command itself requires the guest to be running
users are very likely to manipulate the disk image files while the guest
is running.

This command must prompt the user to shut down the guest before
restoring.

> +
> +    def guest_remove_wrapper(self, args):
> +        """
> +        Wrapper for _guest_remove method.
> +        """
> +        guest_name = args.guest
> +        self._guest_remove(guest_name)
> +        self.write_config()
> +
> +    def list(self, args):
> +        """
> +        Prints guests present in Config file
> +        """
> +        for guest_name in self.config.sections():
> +            print(guest_name)
> +
> +    def guest_add_wrapper(self, args):
> +        """
> +        Wrapper for _quest_add method
> +        """
> +        self._guest_add(args.guest, args.qmp)
> +
> +    def drive_add_wrapper(self, args):
> +        """
> +        Wrapper for _drive_add method
> +        """
> +        self._drive_add(args.id, args.guest, args.target)
> +
> +    def fullbackup_wrapper(self, args):
> +        """
> +        Wrapper for _full_backup method
> +        """
> +        self._full_backup(args.guest)
> +
> +    def restore_wrapper(self, args):
> +        """
> +        Wrapper for restore
> +        """
> +        self._restore(args.guest)
> +
> +
> +def main():
> +    backup_tool = BackupTool()
> +    parser = ArgumentParser()
> +    subparsers = parser.add_subparsers(title='Subcommands',
> +                                       description='Valid Subcommands',
> +                                       help='Subcommand help')
> +    guest_parser = subparsers.add_parser('guest', help='Adds or \
> +                                                   removes and lists guest(s)')
> +    guest_subparsers = guest_parser.add_subparsers(title='Guest Subparser')
> +    guest_list_parser = guest_subparsers.add_parser('list',
> +                                                    help='Lists all guests')
> +    guest_list_parser.set_defaults(func=backup_tool.list)
> +
> +    guest_add_parser = guest_subparsers.add_parser('add', help='Adds a guest')
> +    guest_add_parser.add_argument('--guest', action='store', type=str,
> +                                  help='Name of the guest')
> +    guest_add_parser.add_argument('--qmp', action='store', type=str,
> +                                  help='Path of socket')
> +    guest_add_parser.set_defaults(func=backup_tool.guest_add_wrapper)
> +
> +    guest_remove_parser = guest_subparsers.add_parser('remove',
> +                                                      help='removes a guest')
> +    guest_remove_parser.add_argument('--guest', action='store', type=str,
> +                                     help='Name of the guest')
> +    guest_remove_parser.set_defaults(func=backup_tool.guest_remove_wrapper)
> +
> +    drive_parser = subparsers.add_parser('drive',
> +                                         help='Adds drive(s) for backup')
> +    drive_subparsers = drive_parser.add_subparsers(title='Add subparser',
> +                                                   description='Drive \
> +                                                                subparser')
> +    drive_add_parser = drive_subparsers.add_parser('add',
> +                                                   help='Adds new \
> +                                                         drive for backup')
> +    drive_add_parser.add_argument('--guest', action='store',
> +                                  type=str, help='Name of the guest')
> +    drive_add_parser.add_argument('--id', action='store',
> +                                  type=str, help='Drive ID')
> +    drive_add_parser.add_argument('--target', nargs='?',
> +                                  default=None, help='Destination path')
> +    drive_add_parser.set_defaults(func=backup_tool.drive_add_wrapper)
> +
> +    backup_parser = subparsers.add_parser('backup', help='Creates backup')
> +    backup_parser.add_argument('--guest', action='store',
> +                               type=str, help='Name of the guest')
> +    backup_parser.set_defaults(func=backup_tool.fullbackup_wrapper)
> +
> +    backup_parser = subparsers.add_parser('restore', help='Restores drives')
> +    backup_parser.add_argument('--guest', action='store',
> +                               type=str, help='Name of the guest')
> +    backup_parser.set_defaults(func=backup_tool.restore_wrapper)
> +
> +    args = parser.parse_args()
> +    args.func(args)
> +
> +if __name__ == '__main__':
> +    main()
> -- 
> 2.7.4
>

----- On Aug 22, 2017, at 7:43 PM, stefanha stefanha@redhat.com wrote:

> On Mon, Aug 21, 2017 at 04:40:37PM +0530, Ishani Chugh wrote:
>> qemu-backup will be a command-line tool for performing full and
>> incremental disk backups on running VMs. It is intended as a
>> reference implementation for management stack and backup developers
>> to see QEMU's backup features in action. The tool writes details of
>> guest in a configuration file and the data is retrieved from the file
>> while creating a backup. The location of config file can be set as an
>> environment variable QEMU_BACKUP_CONFIG. The usage is as follows:
>> 
>> Add a guest
>> python qemu-backup.py guest add --guest <guest_name> --qmp <socket_path>
>> 
>> Add a drive for backup in a specified guest
>> python qemu-backup.py drive add --guest <guest_name> --id <drive_id> [--target
>> <target_file_path>]
>> 
>> Create backup of the added drives:
>> python qemu-backup.py backup --guest <guest_name>
>> 
>> List all guest configs in configuration file:
>> python qemu-backup.py guest list
>> 
>> Restore operation
>> python qemu-backup.py restore --guest <guest-name>
>> 
>> Remove a guest
>> python qemu-backup.py guest remove --guest <guest_name>
>> 
>> Signed-off-by: Ishani Chugh <chugh.ishani@research.iiit.ac.in>
>> ---
>>  contrib/backup/qemu-backup.py | 334 ++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 334 insertions(+)
>>  create mode 100644 contrib/backup/qemu-backup.py
>> 
>> diff --git a/contrib/backup/qemu-backup.py b/contrib/backup/qemu-backup.py
>> new file mode 100644
>> index 0000000..08570f7
>> --- /dev/null
>> +++ b/contrib/backup/qemu-backup.py
>> @@ -0,0 +1,334 @@
>> +#!/usr/bin/python
>> +# -*- coding: utf-8 -*-
>> +#
>> +# Copyright (C) 2017 Ishani Chugh <chugh.ishani@research.iiit.ac.in>
>> +#
>> +# This program is free software; you can redistribute it and/or modify
>> +# it under the terms of the GNU General Public License as published by
>> +# the Free Software Foundation; either version 2 of the License, or
>> +# (at your option) any later version.
>> +#
>> +# This program is distributed in the hope that it will be useful,
>> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +# GNU General Public License for more details.
>> +#
>> +# You should have received a copy of the GNU General Public License
>> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> +#
>> +
>> +"""
>> +This file is an implementation of backup tool
>> +"""
>> +from __future__ import print_function
>> +from argparse import ArgumentParser
>> +import os
>> +import errno
>> +from socket import error as socket_error
>> +try:
>> +    import configparser
>> +except ImportError:
>> +    import ConfigParser as configparser
>> +import sys
>> +sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..',
>> +                             'scripts', 'qmp'))
>> +from qmp import QEMUMonitorProtocol
>> +
>> +
>> +class BackupTool(object):
>> +    """BackupTool Class"""
>> +    def __init__(self, config_file=os.path.expanduser('~') +
>> +                 '/.config/qemu/qemu-backup-config'):
>> +        if "QEMU_BACKUP_CONFIG" in os.environ:
>> +            self.config_file = os.environ["QEMU_BACKUP_CONFIG"]
>> +        else:
>> +            self.config_file = config_file
>> +            try:
>> +                if not os.path.isdir(os.path.dirname(self.config_file)):
>> +                    os.makedirs(os.path.dirname(self.config_file))
>> +            except:
>> +                print("Cannot create config directory", file=sys.stderr)
>> +                sys.exit(1)
>> +        self.config = configparser.ConfigParser()
>> +        self.config.read(self.config_file)
>> +
>> +    def write_config(self):
>> +        """
>> +        Writes configuration to ini file.
>> +        """
>> +        config_file = open(self.config_file+".tmp", 'w')
>> +        self.config.write(config_file)
>> +        config_file.flush()
>> +        os.fsync(config_file.fileno())
>> +        config_file.close()
>> +        os.rename(self.config_file+".tmp", self.config_file)
>> +
>> +    def get_socket_address(self, socket_address):
>> +        """
>> +        Return Socket address in form of string or tuple
>> +        """
>> +        if socket_address.startswith('tcp'):
>> +            return (socket_address.split(':')[1],
>> +                    int(socket_address.split(':')[2]))
>> +        return socket_address.split(':', 2)[1]
>> +
>> +    def _full_backup(self, guest_name):
>> +        """
>> +        Performs full backup of guest
>> +        """
>> +        if guest_name not in self.config.sections():
>> +            print("Cannot find specified guest", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        self.verify_guest_running(guest_name)
>> +        connection = QEMUMonitorProtocol(
>> +                                         self.get_socket_address(
>> +                                             self.config[guest_name]['qmp']))
>> +        connection.connect()
>> +        cmd = {"execute": "transaction", "arguments": {"actions": []}}
>> +        drive_list = []
>> +        for key in self.config[guest_name]:
>> +            if key.startswith("drive_"):
>> +                drive = key[len('drive_'):]
>> +                drive_list.append(drive)
>> +                target = self.config[guest_name][key]
>> +                sub_cmd = {"type": "drive-backup", "data": {"device": drive,
>> +                                                            "target": target,
>> +                                                            "sync": "full"}}
>> +                cmd['arguments']['actions'].append(sub_cmd)
>> +        qmp_return = connection.cmd_obj(cmd)
>> +        if 'error' in qmp_return:
>> +            print(qmp_return['error']['desc'], file=sys.stderr)
>> +            sys.exit(1)
>> +        print("Backup Started")
>> +        while len(drive_list) != 0:
>> +            event = connection.pull_event(wait=True)
>> +            if event['event'] == 'SHUTDOWN':
>> +                print("The guest was SHUT DOWN", file=sys.stderr)
>> +                sys.exit(1)
>> +
>> +            if event['event'] == 'RESET':
>> +                print("The guest was Rebooted", file=sys.stderr)
>> +                sys.exit(1)
>> +
>> +            if event['data']['device'] in drive_list and \
>> +                    event['data']['type'] == 'backup':
> 
> At this point the event[] dict might be a non-BLOCK_JOB_* event.
> Therefore event['data']['device'] will raise a KeyError exception.
> 
> You must check event['event'] before assuming it contains certain
> fields.

Agreed. Will fix in next revision.
 
>> +                if event['event'] == 'BLOCK_JOB_COMPLETED':
>> +                    print("*"+event['data']['device'])
>> +                    drive_list.remove(event['data']['device'])
>> +                elif event['event'] == 'BLOCK_JOB_ERROR':
>> +                    print("Cannot Complete Backup", file=sys.stderr)
>> +                    sys.exit(1)
>> +        print("Backup Complete")
>> +
>> +    def _drive_add(self, drive_id, guest_name, target=None):
>> +        """
>> +        Adds drive for backup
>> +        """
>> +        if target is None:
>> +            target = os.path.abspath(drive_id)
>> +
>> +        if os.path.isdir(os.path.dirname(target)) is False:
>> +            print("Cannot find target directory", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        if guest_name not in self.config.sections():
>> +            print("Cannot find specified guest", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        if "drive_"+drive_id in self.config[guest_name]:
>> +            print("Drive already marked for backup", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        self.verify_guest_running(guest_name)
>> +
>> +        connection = QEMUMonitorProtocol(
>> +                                         self.get_socket_address(
>> +                                             self.config[guest_name]['qmp']))
>> +        connection.connect()
>> +        cmd = {'execute': 'query-block'}
>> +        returned_json = connection.cmd_obj(cmd)
>> +        device_present = False
>> +        for device in returned_json['return']:
>> +            if device['device'] == drive_id:
>> +                device_present = True
>> +                break
>> +
>> +        if not device_present:
>> +            print("No such drive in guest", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        drive_id = "drive_" + drive_id
>> +        for d_id in self.config[guest_name]:
>> +            if self.config[guest_name][d_id] == target:
>> +                print("Please choose different target", file=sys.stderr)
>> +                sys.exit(1)
>> +        self.config.set(guest_name, drive_id, target)
>> +        self.write_config()
>> +        print("Successfully Added Drive")
>> +
>> +    def verify_guest_running(self, guest_name):
>> +        """
>> +        Checks whether specified guest is running or not
>> +        """
>> +        socket_address = self.config.get(guest_name, 'qmp')
>> +        try:
>> +            connection = QEMUMonitorProtocol(self.get_socket_address(
>> +                                             socket_address))
>> +            connection.connect()
>> +        except socket_error:
>> +            if socket_error.errno != errno.ECONNREFUSED:
>> +                print("Connection to guest refused", file=sys.stderr)
>> +                sys.exit(1)
>> +
>> +    def _guest_add(self, guest_name, socket_address):
>> +        """
>> +        Adds a guest to the config file
>> +        """
>> +        if guest_name in self.config.sections():
>> +            print("ID already exists. Please choose a different guestname",
>> +                  file=sys.stderr)
>> +            sys.exit(1)
>> +        self.config[guest_name] = {'qmp': socket_address}
>> +        self.verify_guest_running(guest_name)
>> +        self.write_config()
>> +        print("Successfully Added Guest")
>> +
>> +    def _guest_remove(self, guest_name):
>> +        """
>> +        Removes a guest from config file
>> +        """
>> +        if guest_name not in self.config.sections():
>> +            print("Guest Not present", file=sys.stderr)
>> +            sys.exit(1)
>> +        self.config.remove_section(guest_name)
>> +        print("Guest successfully deleted")
>> +
>> +    def _restore(self, guest_name):
>> +        """
>> +        Prints Steps to perform restore operation
>> +        """
>> +        if guest_name not in self.config.sections():
>> +            print("Cannot find specified guest", file=sys.stderr)
>> +            sys.exit(1)
>> +
>> +        self.verify_guest_running(guest_name)
>> +        connection = QEMUMonitorProtocol(
>> +                                         self.get_socket_address(
>> +                                             self.config[guest_name]['qmp']))
>> +        connection.connect()
>> +        print("To perform restore, replace:")
>> +        for key in self.config[guest_name]:
>> +            if key.startswith("drive_"):
>> +                drive = key[len('drive_'):]
>> +                target = self.config[guest_name][key]
>> +                cmd = {'execute': 'query-block'}
>> +                returned_json = connection.cmd_obj(cmd)
>> +                device_present = False
>> +                for device in returned_json['return']:
>> +                    if device['device'] == drive:
>> +                        device_present = True
>> +                        location = device['inserted']['image']['filename']
>> +                        print(location+" By "+target)
> 
> I suggest print('Replace ' + location + ' with ' + target) for a
> slightly clearer message.

Will fix in next revision.

>> +
>> +                if not device_present:
>> +                    print("No such drive in guest", file=sys.stderr)
>> +                    sys.exit(1)
> 
> Since the command itself requires the guest to be running
> users are very likely to manipulate the disk image files while the guest
> is running.
> 
> This command must prompt the user to shut down the guest before
> restoring.

The intention behind this condition is the case where user may have detached
a disk from the guest(and have rerun the guest). I will put up the message to
shut down the guest. 

>> +
>> +    def guest_remove_wrapper(self, args):
>> +        """
>> +        Wrapper for _guest_remove method.
>> +        """
>> +        guest_name = args.guest
>> +        self._guest_remove(guest_name)
>> +        self.write_config()
>> +
>> +    def list(self, args):
>> +        """
>> +        Prints guests present in Config file
>> +        """
>> +        for guest_name in self.config.sections():
>> +            print(guest_name)
>> +
>> +    def guest_add_wrapper(self, args):
>> +        """
>> +        Wrapper for _quest_add method
>> +        """
>> +        self._guest_add(args.guest, args.qmp)
>> +
>> +    def drive_add_wrapper(self, args):
>> +        """
>> +        Wrapper for _drive_add method
>> +        """
>> +        self._drive_add(args.id, args.guest, args.target)
>> +
>> +    def fullbackup_wrapper(self, args):
>> +        """
>> +        Wrapper for _full_backup method
>> +        """
>> +        self._full_backup(args.guest)
>> +
>> +    def restore_wrapper(self, args):
>> +        """
>> +        Wrapper for restore
>> +        """
>> +        self._restore(args.guest)
>> +
>> +
>> +def main():
>> +    backup_tool = BackupTool()
>> +    parser = ArgumentParser()
>> +    subparsers = parser.add_subparsers(title='Subcommands',
>> +                                       description='Valid Subcommands',
>> +                                       help='Subcommand help')
>> +    guest_parser = subparsers.add_parser('guest', help='Adds or \
>> +                                                   removes and lists guest(s)')
>> +    guest_subparsers = guest_parser.add_subparsers(title='Guest Subparser')
>> +    guest_list_parser = guest_subparsers.add_parser('list',
>> +                                                    help='Lists all guests')
>> +    guest_list_parser.set_defaults(func=backup_tool.list)
>> +
>> +    guest_add_parser = guest_subparsers.add_parser('add', help='Adds a guest')
>> +    guest_add_parser.add_argument('--guest', action='store', type=str,
>> +                                  help='Name of the guest')
>> +    guest_add_parser.add_argument('--qmp', action='store', type=str,
>> +                                  help='Path of socket')
>> +    guest_add_parser.set_defaults(func=backup_tool.guest_add_wrapper)
>> +
>> +    guest_remove_parser = guest_subparsers.add_parser('remove',
>> +                                                      help='removes a guest')
>> +    guest_remove_parser.add_argument('--guest', action='store', type=str,
>> +                                     help='Name of the guest')
>> +    guest_remove_parser.set_defaults(func=backup_tool.guest_remove_wrapper)
>> +
>> +    drive_parser = subparsers.add_parser('drive',
>> +                                         help='Adds drive(s) for backup')
>> +    drive_subparsers = drive_parser.add_subparsers(title='Add subparser',
>> +                                                   description='Drive \
>> +                                                                subparser')
>> +    drive_add_parser = drive_subparsers.add_parser('add',
>> +                                                   help='Adds new \
>> +                                                         drive for backup')
>> +    drive_add_parser.add_argument('--guest', action='store',
>> +                                  type=str, help='Name of the guest')
>> +    drive_add_parser.add_argument('--id', action='store',
>> +                                  type=str, help='Drive ID')
>> +    drive_add_parser.add_argument('--target', nargs='?',
>> +                                  default=None, help='Destination path')
>> +    drive_add_parser.set_defaults(func=backup_tool.drive_add_wrapper)
>> +
>> +    backup_parser = subparsers.add_parser('backup', help='Creates backup')
>> +    backup_parser.add_argument('--guest', action='store',
>> +                               type=str, help='Name of the guest')
>> +    backup_parser.set_defaults(func=backup_tool.fullbackup_wrapper)
>> +
>> +    backup_parser = subparsers.add_parser('restore', help='Restores drives')
>> +    backup_parser.add_argument('--guest', action='store',
>> +                               type=str, help='Name of the guest')
>> +    backup_parser.set_defaults(func=backup_tool.restore_wrapper)
>> +
>> +    args = parser.parse_args()
>> +    args.func(args)
>> +
>> +if __name__ == '__main__':
>> +    main()
>> --
>> 2.7.4

Thanks for review.