[Qemu-devel] [PATCH 1/3] backup: QEMU Backup Tool

[Ishani Chugh <chugh.ishani@research.iiit.ac.in>]

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 | 335 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 335 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..c8032de
--- /dev/null
+++ b/contrib/backup/qemu-backup.py
@@ -0,0 +1,335 @@
+#!/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'] == 'BLOCK_JOB_COMPLETED':
+                if event['data']['device'] in drive_list and \
+                        event['data']['type'] == 'backup':
+                        print("*" + event['data']['device'])
+                        drive_list.remove(event['data']['device'])
+
+            if event['event'] == 'BLOCK_JOB_ERROR':
+                if event['data']['device'] in drive_list and \
+                        event['data']['type'] == 'backup':
+                        print(event['data']['device'] + " Backup Failed",
+                              file=sys.stderr)
+                        drive_list.remove(event['data']['device'])
+        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:")
+        print("Shut down guest")
+        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("Replace " + location + " By " + target)
+
+                if not device_present:
+                    print("No such drive in guest", file=sys.stderr)
+                    sys.exit(1)
+
+    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