vmdebootstrap

   1 #!/usr/bin/python
   2 # Copyright 2011  Lars Wirzenius
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import cliapp
  18 import logging
  19 import os
  20 import re
  21 import shutil
  22 import subprocess
  23 import tempfile
  24
  25
  26 class VmDebootstrap(cliapp.Application):
  27
  28     def add_settings(self):
  29         default_arch = 'amd64'
  30
  31         self.settings.add_boolean_setting(['verbose'],
  32                                           'report what is going on')
  33         self.settings.add_string_setting(['image'],
  34                                          'put created disk image in FILE',
  35                                          metavar='FILE')
  36         self.settings.add_bytesize_setting(['size'],
  37                                            'create a disk image of size SIZE '
  38                                             '(%default)',
  39                                            metavar='SIZE',
  40                                            default='1G')
  41         self.settings.add_string_setting(['mirror'],
  42                                          'use MIRROR as package source '
  43                                             '(%default)',
  44                                      default='http://cdn.debian.net/debian/')
  45         self.settings.add_string_setting(['arch'],
  46                                          'architecture to use '
  47                                             '(%default)',
  48                                          metavar='ARCH',
  49                                          default=default_arch)
  50         self.settings.add_string_setting(['distribution'],
  51                                          'release to use (%default)',
  52                                          metavar='NAME',
  53                                          default='stable')
  54
  55     def process_args(self, args):
  56         if not self.settings['image']:
  57             raise cliapp.AppException('You must give image filename.')
  58         if not self.settings['size']:
  59             raise cliapp.AppException('You must give image size.')
  60
  61         self.remove_dirs = []
  62         self.mount_points = []
  63
  64         try:
  65             self.create_empty_image()
  66             self.partition_image()
  67             self.install_mbr()
  68             rootdev = self.setup_kpartx()
  69             self.mkfs(rootdev)
  70             rootdir = self.mount(rootdev)
  71             self.debootstrap(rootdir)
  72             self.set_root_password(rootdir)
  73             self.install_extlinux(rootdev, rootdir)
  74         except:
  75             self.cleanup()
  76             raise
  77         else:
  78             self.cleanup()
  79
  80     def message(self, msg):
  81         if self.settings['verbose']:
  82             print msg
  83
  84     def runcmd(self, argv, stdin='', ignore_fail=False, **kwargs):
  85         logging.debug('runcmd: %s %s' % (argv, kwargs))
  86         p = subprocess.Popen(argv, stdin=subprocess.PIPE,
  87                              stdout=subprocess.PIPE, stderr=subprocess.PIPE,
  88                              **kwargs)
  89         out, err = p.communicate(stdin)
  90         if p.returncode != 0:
  91             msg = 'command failed: %s\n%s' % (argv, err)
  92             logging.error(msg)
  93             if not ignore_fail:
  94                 raise cliapp.AppException(msg)
  95         return out
  96
  97     def mkdtemp(self):
  98         dirname = tempfile.mkdtemp()
  99         self.remove_dirs.append(dirname)
 100         logging.debug('mkdir %s' % dirname)
 101         return dirname
 102
 103     def mount(self, device):
 104         self.message('Mounting %s' % device)
 105         mount_point = self.mkdtemp()
 106         self.runcmd(['mount', device, mount_point])
 107         self.mount_points.append(mount_point)
 108         logging.debug('mounted %s on %s' % (device, mount_point))
 109         return mount_point
 110
 111     def create_empty_image(self):
 112         self.message('Creating disk image')
 113         self.runcmd(['qemu-img', 'create', '-f', 'raw',
 114                      self.settings['image'],
 115                      str(self.settings['size'])])
 116
 117     def partition_image(self):
 118         self.message('Creating partitions')
 119         self.runcmd(['parted', '-s', self.settings['image'],
 120                      'mklabel', 'msdos'])
 121         self.runcmd(['parted', '-s', self.settings['image'],
 122                      'mkpart', 'primary', '0%', '100%'])
 123         self.runcmd(['parted', '-s', self.settings['image'],
 124                      'set', '1', 'boot', 'on'])
 125
 126     def install_mbr(self):
 127         self.message('Installing MBR')
 128         self.runcmd(['install-mbr', self.settings['image']])
 129
 130     def setup_kpartx(self):
 131         out = self.runcmd(['kpartx', '-av', self.settings['image']])
 132         devices = [line.split()[2]
 133                    for line in out.splitlines()
 134                    if line.startswith('add map ')]
 135         if len(devices) != 1:
 136             raise cliapp.AppException('Surprising number of partitions')
 137         return '/dev/mapper/%s' % devices[0]
 138
 139     def mkfs(self, device):
 140         self.message('Creating filesystem')
 141         self.runcmd(['mkfs', '-t', 'ext2', device])
 142
 143     def debootstrap(self, rootdir):
 144         self.message('Debootstrapping')
 145
 146         if self.settings['arch'] == 'i386':
 147             kernel_arch = 'i686'
 148         else:
 149             kernel_arch = self.settings['arch']
 150         kernel_image = 'linux-image-2.6-%s' % kernel_arch
 151
 152         include = [kernel_image]
 153
 154         self.runcmd(['debootstrap',
 155                      '--arch=%s' % self.settings['arch'],
 156                      '--include=%s' % ','.join(include),
 157                      self.settings['distribution'],
 158                      rootdir,
 159                      self.settings['mirror']])
 160
 161     def set_root_password(self, rootdir):
 162         self.message('Removing root password')
 163         self.runcmd(['chroot', rootdir, 'passwd', '-d', 'root'])
 164
 165     def install_extlinux(self, rootdev, rootdir):
 166         self.message('Installing extlinux')
 167
 168         def find(pattern):
 169             dirname = os.path.join(rootdir, 'boot')
 170             basenames = os.listdir(dirname)
 171             logging.debug('find: %s' % basenames)
 172             for basename in basenames:
 173                 if re.search(pattern, basename):
 174                     return os.path.join('boot', basename)
 175             raise cliapp.AppException('Cannot find match: %s' % pattern)
 176
 177         kernel_image = find('vmlinuz-.*')
 178         initrd_image = find('initrd.img-.*')
 179
 180         out = self.runcmd(['blkid', '-c', '/dev/null', '-o', 'value',
 181                            '-s', 'UUID', rootdev])
 182         uuid = out.splitlines()[0].strip()
 183
 184         conf = os.path.join(rootdir, 'extlinux.conf')
 185         logging.debug('configure extlinux %s' % conf)
 186         f = open(conf, 'w')
 187         f.write('''
 188 default linux
 189 timeout 1
 190
 191 label linux
 192 kernel %(kernel)s
 193 append initrd=%(initrd)s root=UUID=%(uuid)s ro
 194 ''' % {
 195     'kernel': kernel_image,
 196     'initrd': initrd_image,
 197     'uuid': uuid,
 198 })
 199         f.close()
 200
 201         self.runcmd(['extlinux', '--install', rootdir])
 202         self.runcmd(['sync'])
 203         import time; time.sleep(2)
 204
 205     def cleanup(self):
 206         # Clean up after any errors.
 207
 208         self.message('Cleaning up')
 209
 210         for mount_point in self.mount_points:
 211             self.runcmd(['umount', mount_point], ignore_fail=True)
 212
 213         self.runcmd(['kpartx', '-d', self.settings['image']], ignore_fail=True)
 214
 215         for dirname in self.remove_dirs:
 216             shutil.rmtree(dirname)
 217
 218
 219 if __name__ == '__main__':
 220     VmDebootstrap().run()
 221