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                                          metavar='URL',
  45                                      default='http://cdn.debian.net/debian/')
  46         self.settings.add_string_setting(['arch'],
  47                                          'architecture to use '
  48                                             '(%default)',
  49                                          metavar='ARCH',
  50                                          default=default_arch)
  51         self.settings.add_string_setting(['distribution'],
  52                                          'release to use (%default)',
  53                                          metavar='NAME',
  54                                          default='stable')
  55
  56     def process_args(self, args):
  57         if not self.settings['image']:
  58             raise cliapp.AppException('You must give image filename.')
  59         if not self.settings['size']:
  60             raise cliapp.AppException('You must give image size.')
  61
  62         self.remove_dirs = []
  63         self.mount_points = []
  64
  65         try:
  66             self.create_empty_image()
  67             self.partition_image()
  68             self.install_mbr()
  69             rootdev = self.setup_kpartx()
  70             self.mkfs(rootdev)
  71             rootdir = self.mount(rootdev)
  72             self.debootstrap(rootdir)
  73             self.set_root_password(rootdir)
  74             self.install_extlinux(rootdev, rootdir)
  75         except:
  76             self.cleanup()
  77             raise
  78         else:
  79             self.cleanup()
  80
  81     def message(self, msg):
  82         if self.settings['verbose']:
  83             print msg
  84
  85     def runcmd(self, argv, stdin='', ignore_fail=False, **kwargs):
  86         logging.debug('runcmd: %s %s' % (argv, kwargs))
  87         p = subprocess.Popen(argv, stdin=subprocess.PIPE,
  88                              stdout=subprocess.PIPE, stderr=subprocess.PIPE,
  89                              **kwargs)
  90         out, err = p.communicate(stdin)
  91         if p.returncode != 0:
  92             msg = 'command failed: %s\n%s' % (argv, err)
  93             logging.error(msg)
  94             if not ignore_fail:
  95                 raise cliapp.AppException(msg)
  96         return out
  97
  98     def mkdtemp(self):
  99         dirname = tempfile.mkdtemp()
 100         self.remove_dirs.append(dirname)
 101         logging.debug('mkdir %s' % dirname)
 102         return dirname
 103
 104     def mount(self, device):
 105         self.message('Mounting %s' % device)
 106         mount_point = self.mkdtemp()
 107         self.runcmd(['mount', device, mount_point])
 108         self.mount_points.append(mount_point)
 109         logging.debug('mounted %s on %s' % (device, mount_point))
 110         return mount_point
 111
 112     def create_empty_image(self):
 113         self.message('Creating disk image')
 114         self.runcmd(['qemu-img', 'create', '-f', 'raw',
 115                      self.settings['image'],
 116                      str(self.settings['size'])])
 117
 118     def partition_image(self):
 119         self.message('Creating partitions')
 120         self.runcmd(['parted', '-s', self.settings['image'],
 121                      'mklabel', 'msdos'])
 122         self.runcmd(['parted', '-s', self.settings['image'],
 123                      'mkpart', 'primary', '0%', '100%'])
 124         self.runcmd(['parted', '-s', self.settings['image'],
 125                      'set', '1', 'boot', 'on'])
 126
 127     def install_mbr(self):
 128         self.message('Installing MBR')
 129         self.runcmd(['install-mbr', self.settings['image']])
 130
 131     def setup_kpartx(self):
 132         out = self.runcmd(['kpartx', '-av', self.settings['image']])
 133         devices = [line.split()[2]
 134                    for line in out.splitlines()
 135                    if line.startswith('add map ')]
 136         if len(devices) != 1:
 137             raise cliapp.AppException('Surprising number of partitions')
 138         return '/dev/mapper/%s' % devices[0]
 139
 140     def mkfs(self, device):
 141         self.message('Creating filesystem')
 142         self.runcmd(['mkfs', '-t', 'ext2', device])
 143
 144     def debootstrap(self, rootdir):
 145         self.message('Debootstrapping')
 146
 147         if self.settings['arch'] == 'i386':
 148             kernel_arch = 'i686'
 149         else:
 150             kernel_arch = self.settings['arch']
 151         kernel_image = 'linux-image-2.6-%s' % kernel_arch
 152
 153         include = [kernel_image]
 154
 155         self.runcmd(['debootstrap',
 156                      '--arch=%s' % self.settings['arch'],
 157                      '--include=%s' % ','.join(include),
 158                      self.settings['distribution'],
 159                      rootdir,
 160                      self.settings['mirror']])
 161
 162     def set_root_password(self, rootdir):
 163         self.message('Removing root password')
 164         self.runcmd(['chroot', rootdir, 'passwd', '-d', 'root'])
 165
 166     def install_extlinux(self, rootdev, rootdir):
 167         self.message('Installing extlinux')
 168
 169         def find(pattern):
 170             dirname = os.path.join(rootdir, 'boot')
 171             basenames = os.listdir(dirname)
 172             logging.debug('find: %s' % basenames)
 173             for basename in basenames:
 174                 if re.search(pattern, basename):
 175                     return os.path.join('boot', basename)
 176             raise cliapp.AppException('Cannot find match: %s' % pattern)
 177
 178         kernel_image = find('vmlinuz-.*')
 179         initrd_image = find('initrd.img-.*')
 180
 181         out = self.runcmd(['blkid', '-c', '/dev/null', '-o', 'value',
 182                            '-s', 'UUID', rootdev])
 183         uuid = out.splitlines()[0].strip()
 184
 185         conf = os.path.join(rootdir, 'extlinux.conf')
 186         logging.debug('configure extlinux %s' % conf)
 187         f = open(conf, 'w')
 188         f.write('''
 189 default linux
 190 timeout 1
 191
 192 label linux
 193 kernel %(kernel)s
 194 append initrd=%(initrd)s root=UUID=%(uuid)s ro
 195 ''' % {
 196     'kernel': kernel_image,
 197     'initrd': initrd_image,
 198     'uuid': uuid,
 199 })
 200         f.close()
 201
 202         self.runcmd(['extlinux', '--install', rootdir])
 203         self.runcmd(['sync'])
 204         import time; time.sleep(2)
 205
 206     def cleanup(self):
 207         # Clean up after any errors.
 208
 209         self.message('Cleaning up')
 210
 211         for mount_point in self.mount_points:
 212             self.runcmd(['umount', mount_point], ignore_fail=True)
 213
 214         self.runcmd(['kpartx', '-d', self.settings['image']], ignore_fail=True)
 215
 216         for dirname in self.remove_dirs:
 217             shutil.rmtree(dirname)
 218
 219
 220 if __name__ == '__main__':
 221     VmDebootstrap().run()
 222