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# Copyright (C) 2012-2013 Codethink Limited
#
# 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; version 2 of the License.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
import cliapp
import os
import re
import sys
import time
import tempfile
class WriteExtension(cliapp.Application):
'''A base class for deployment write extensions.
A subclass should subclass this class, and add a
``process_args`` method.
Note that it is not necessary to subclass this class for write
extensions. This class is here just to collect common code for
write extensions.
'''
def process_args(self, args):
raise NotImplementedError()
def status(self, **kwargs):
'''Provide status output.
The ``msg`` keyword argument is the actual message,
the rest are values for fields in the message as interpolated
by %.
'''
self.output.write('%s\n' % (kwargs['msg'] % kwargs))
def create_local_system(self, temp_root, raw_disk):
'''Create a raw system image locally.'''
size = self.get_disk_size()
self.create_raw_disk_image(raw_disk, size)
try:
self.mkfs_btrfs(raw_disk)
mp = self.mount(raw_disk)
except BaseException:
sys.stderr.write('Error creating disk image')
os.remove(raw_disk)
raise
try:
self.create_factory(mp, temp_root)
self.create_fstab(mp)
self.create_factory_run(mp)
self.install_extlinux(mp)
except BaseException, e:
sys.stderr.write('Error creating disk image')
self.unmount(mp)
os.remove(raw_disk)
raise
else:
self.unmount(mp)
def get_disk_size(self):
'''Parse disk size from environment.'''
size = os.environ.get('DISK_SIZE', '1G')
m = re.match('^(\d+)([kmgKMG]?)$', size)
if not m:
raise morphlib.Error('Cannot parse disk size %s' % size)
factors = {
'': 1,
'k': 1024,
'm': 1024**2,
'g': 1024**3,
}
factor = factors[m.group(2).lower()]
return int(m.group(1)) * factor
def create_raw_disk_image(self, filename, size):
'''Create a raw disk image.'''
self.status(msg='Creating empty disk image')
with open(filename, 'wb') as f:
if size > 0:
f.seek(size-1)
f.write('\0')
def mkfs_btrfs(self, location):
'''Create a btrfs filesystem on the disk.'''
self.status(msg='Creating btrfs filesystem')
cliapp.runcmd(['mkfs.btrfs', '-L', 'baserock', location])
def mount(self, location):
'''Mount the filesystem so it can be tweaked.
Return path to the mount point.
The mount point is a newly created temporary directory.
The caller must call self.unmount to unmount on the return value.
'''
self.status(msg='Mounting filesystem')
tempdir = tempfile.mkdtemp()
cliapp.runcmd(['mount', '-o', 'loop', location, tempdir])
return tempdir
def unmount(self, mount_point):
'''Unmount the filesystem mounted by self.mount.
Also, remove the temporary directory.
'''
self.status(msg='Unmounting filesystem')
cliapp.runcmd(['umount', mount_point])
os.rmdir(mount_point)
def create_factory(self, real_root, temp_root):
'''Create the default "factory" system.'''
factory = os.path.join(real_root, 'factory')
self.status(msg='Creating factory subvolume')
cliapp.runcmd(['btrfs', 'subvolume', 'create', factory])
self.status(msg='Copying files to factory subvolume')
cliapp.runcmd(['cp', '-a', temp_root + '/.', factory + '/.'])
# The kernel needs to be on the root volume.
self.status(msg='Copying boot directory to root subvolume')
factory_boot = os.path.join(factory, 'boot')
root_boot = os.path.join(real_root, 'boot')
cliapp.runcmd(['cp', '-a', factory_boot, root_boot])
def create_factory_run(self, real_root):
'''Create the 'factory-run' snapshot.'''
self.status(msg='Creating factory-run subvolume')
factory = os.path.join(real_root, 'factory')
factory_run = factory + '-run'
cliapp.runcmd(
['btrfs', 'subvolume', 'snapshot', factory, factory_run])
def create_fstab(self, real_root):
'''Create an fstab.'''
self.status(msg='Creating fstab')
fstab = os.path.join(real_root, 'factory', 'etc', 'fstab')
with open(fstab, 'w') as f:
f.write('/dev/sda / btrfs defaults,rw,noatime 0 1\n')
def install_extlinux(self, real_root):
'''Install extlinux on the newly created disk image.'''
self.status(msg='Creating extlinux.conf')
config = os.path.join(real_root, 'extlinux.conf')
with open(config, 'w') as f:
f.write('default linux\n')
f.write('timeout 1\n')
f.write('label linux\n')
f.write('kernel /boot/vmlinuz\n')
f.write('append root=/dev/sda rootflags=subvol=factory-run '
'init=/sbin/init rw\n')
self.status(msg='Installing extlinux')
cliapp.runcmd(['extlinux', '--install', real_root])
# FIXME this hack seems to be necessary to let extlinux finish
cliapp.runcmd(['sync'])
time.sleep(2)
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