X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/b0376b3fa9916be57a7847467e7f1ac42705d25b..cd8229788cecd69111c23a4d9cf445f349f7be4b:/image_creator/bundle_volume.py diff --git a/image_creator/bundle_volume.py b/image_creator/bundle_volume.py index e373f88..eec084f 100644 --- a/image_creator/bundle_volume.py +++ b/image_creator/bundle_volume.py @@ -1,3 +1,5 @@ +# -*- coding: utf-8 -*- +# # Copyright 2012 GRNET S.A. All rights reserved. # # Redistribution and use in source and binary forms, with or @@ -31,6 +33,11 @@ # interpreted as representing official policies, either expressed # or implied, of GRNET S.A. +"""This module hosts the code that performes the host bundling operation. By +using the create_image method of the BundleVolume class the user can create an +image out of the running system. +""" + import os import re import tempfile @@ -53,6 +60,7 @@ losetup = get_command('losetup') mount = get_command('mount') umount = get_command('umount') blkid = get_command('blkid') +tune2fs = get_command('tune2fs') MKFS_OPTS = {'ext2': ['-F'], 'ext3': ['-F'], @@ -92,6 +100,7 @@ class BundleVolume(object): self.disk = parted.Disk(device) def _read_fstable(self, f): + """Use this generator to iterate over the lines of and fstab file""" if not os.path.isfile(f): raise FatalError("Unable to open: `%s'. File is missing." % f) @@ -106,6 +115,7 @@ class BundleVolume(object): yield FileSystemTableEntry(*entry) def _get_root_partition(self): + """Return the fstab entry accosiated with the root filesystem""" for entry in self._read_fstable('/etc/fstab'): if entry.mpoint == '/': return entry.dev @@ -113,12 +123,14 @@ class BundleVolume(object): raise FatalError("Unable to find root device in /etc/fstab") def _is_mpoint(self, path): + """Check if a directory is currently a mount point""" for entry in self._read_fstable('/proc/mounts'): if entry.mpoint == path: return True return False def _get_mount_options(self, device): + """Return the mount entry associated with a mounted device""" for entry in self._read_fstable('/proc/mounts'): if not entry.dev.startswith('/'): continue @@ -129,9 +141,10 @@ class BundleVolume(object): return None def _create_partition_table(self, image): + """Copy the partition table of the host system into the image""" # Copy the MBR and the space between the MBR and the first partition. - # In msdos partitons tables Grub Stage 1.5 is located there. + # In msdos partition tables Grub Stage 1.5 is located there. # In gpt partition tables the Primary GPT Header is there. first_sector = self.disk.getPrimaryPartitions()[0].geometry.start @@ -143,9 +156,9 @@ class BundleVolume(object): # Copy the Secondary GPT Header table = GPTPartitionTable(self.disk.device.path) dd('if=%s' % self.disk.device.path, 'of=%s' % image, - 'bs=%d' % self.disk.device.sectorSize, 'conv=notrunc', - 'seek=%d' % table.primary.last_usable_lba, - 'skip=%d' % table.primary.last_usable_lba) + 'bs=%d' % self.disk.device.sectorSize, 'conv=notrunc', + 'seek=%d' % table.primary.last_usable_lba, + 'skip=%d' % table.primary.last_usable_lba) # Create the Extended boot records (EBRs) in the image extended = self.disk.getExtendedPartition() @@ -163,6 +176,7 @@ class BundleVolume(object): start = logical[i].geometry.end + 1 def _get_partitions(self, disk): + """Returns a list with the partitions of the provided disk""" Partition = namedtuple('Partition', 'num start end type fs') partitions = [] @@ -177,7 +191,10 @@ class BundleVolume(object): return partitions def _shrink_partitions(self, image): - + """Remove the last partition of the image if it is a swap partition and + shrink the partition before that. Make sure it can still host all the + files the corresponding host file system hosts + """ new_end = self.disk.device.length image_disk = parted.Disk(parted.Device(image)) @@ -222,9 +239,13 @@ class BundleVolume(object): # Align to 2048 part_end = ((part_end + 2047) // 2048) * 2048 + # Make sure the partition starts where the old partition started. + constraint = parted.Constraint(device=image_disk.device) + constraint.startRange = parted.Geometry(device=image_disk.device, + start=last.start, length=1) + image_disk.setPartitionGeometry( - image_disk.getPartitionBySector(last.start), - parted.Constraint(device=image_disk.device), + image_disk.getPartitionBySector(last.start), constraint, start=last.start, end=part_end) image_disk.commitToDevice() @@ -242,6 +263,7 @@ class BundleVolume(object): return (new_end, self._get_partitions(image_disk)) def _map_partition(self, dev, num, start, end): + """Map a partition into a block device using the device mapper""" name = os.path.basename(dev) + "_" + uuid.uuid4().hex tablefd, table = tempfile.mkstemp() try: @@ -254,21 +276,28 @@ class BundleVolume(object): return "/dev/mapper/%sp%d" % (name, num) def _unmap_partition(self, dev): + """Unmap a previously mapped partition""" if not os.path.exists(dev): return try_fail_repeat(dmsetup, 'remove', dev.split('/dev/mapper/')[1]) def _mount(self, target, devs): - + """Mount a list of filesystems in mountpoints relative to target""" devs.sort(key=lambda d: d[1]) - for dev, mpoint in devs: + for dev, mpoint, options in devs: absmpoint = os.path.abspath(target + mpoint) if not os.path.exists(absmpoint): os.makedirs(absmpoint) - mount(dev, absmpoint) + + if len(options) > 0: + mount(dev, absmpoint, '-o', ",".join(options)) + else: + mount(dev, absmpoint) def _umount_all(self, target): + """Unmount all filesystems that are mounted under the directory target + """ mpoints = [] for entry in self._read_fstable('/proc/mounts'): if entry.mpoint.startswith(os.path.abspath(target)): @@ -279,6 +308,10 @@ class BundleVolume(object): try_fail_repeat(umount, mpoint) def _to_exclude(self): + """Find which directories to exclude during the image copy. This is + accompliced by checking which directories serve as mount points for + virtual file systems + """ excluded = ['/tmp', '/var/tmp'] if self.tmp is not None: excluded.append(self.tmp) @@ -314,6 +347,9 @@ class BundleVolume(object): return excluded def _replace_uuids(self, target, new_uuid): + """Replace UUID references in various files. This is needed after + copying system files of the host into a new filesystem + """ files = ['/etc/fstab', '/boot/grub/grub.cfg', @@ -339,10 +375,16 @@ class BundleVolume(object): dest.write(line) def _create_filesystems(self, image, partitions): + """Fill the image with data. Host file systems that are not currently + mounted are binary copied into the image. For mounted file systems, a + file system level copy is performed. + """ filesystem = {} + orig_dev = {} for p in self.disk.partitions: filesystem[p.number] = self._get_mount_options(p.path) + orig_dev[p.number] = p.path unmounted = filter(lambda p: filesystem[p.num] is None, partitions) mounted = filter(lambda p: filesystem[p.num] is not None, partitions) @@ -350,11 +392,15 @@ class BundleVolume(object): # For partitions that are not mounted right now, we can simply dd them # into the image. for p in unmounted: + self.out.output('Cloning partition %d ... ' % p.num, False) dd('if=%s' % self.disk.device.path, 'of=%s' % image, 'count=%d' % (p.end - p.start + 1), 'conv=notrunc', 'seek=%d' % p.start, 'skip=%d' % p.start) + self.out.success("done") loop = str(losetup('-f', '--show', image)).strip() + + # Recreate mounted file systems mapped = {} try: for p in mounted: @@ -368,21 +414,40 @@ class BundleVolume(object): self.out.output('Creating %s filesystem on partition %d ... ' % (fs, i), False) get_command('mkfs.%s' % fs)(*(MKFS_OPTS[fs] + [dev])) + + # For ext[234] enable the default mount options + if re.match('^ext[234]$', fs): + mopts = filter( + lambda p: p.startswith('Default mount options:'), + tune2fs('-l', orig_dev[i]).splitlines() + )[0].split(':')[1].strip().split() + + if not (len(mopts) == 1 and mopts[0] == '(none)'): + for opt in mopts: + tune2fs('-o', opt, dev) + self.out.success('done') new_uuid[i] = blkid( '-s', 'UUID', '-o', 'value', dev).stdout.strip() target = tempfile.mkdtemp() + devs = [] + for i in mapped.keys(): + fs = filesystem[i].fs + mpoint = filesystem[i].mpoint + opts = [] + for opt in filesystem[i].opts.split(','): + if opt in ('acl', 'user_xattr'): + opts.append(opt) + devs.append((mapped[i], mpoint, opts)) try: - absmpoints = self._mount(target, - [(mapped[i], filesystem[i].mpoint) - for i in mapped.keys()]) + self._mount(target, devs) + excluded = self._to_exclude() rsync = Rsync(self.out) - # Excluded paths need to be relative to the source - for excl in map(lambda p: p[1:], excluded + [image]): + for excl in excluded + [image]: rsync.exclude(excl) rsync.archive().hard_links().xattrs().sparse().acls() @@ -393,10 +458,22 @@ class BundleVolume(object): # directory. Make them inherit those properties from their # parent dir for excl in excluded: - dirname = os.path.dirname(excl) - stat = os.stat(dirname) - os.mkdir(target + excl, stat.st_mode) - os.chown(target + excl, stat.st_uid, stat.st_gid) + dirname = os.path.dirname(excl) + stat = os.stat(dirname) + os.mkdir(target + excl) + os.chmod(target + excl, stat.st_mode) + os.chown(target + excl, stat.st_uid, stat.st_gid) + + # /tmp and /var/tmp are special cases. We exclude then even if + # they aren't mountpoints. Restore their permissions. + for excl in ('/tmp', '/var/tmp'): + if self._is_mpoint(excl): + os.chmod(target + excl, 041777) + os.chown(target + excl, 0, 0) + else: + stat = os.stat(excl) + os.chmod(target + excl, stat.st_mode) + os.chown(target + excl, stat.st_uid, stat.st_gid) # We need to replace the old UUID referencies with the new # ones in grub configuration files and /etc/fstab for file @@ -449,8 +526,8 @@ class BundleVolume(object): dirname = os.path.dirname(image) self.out.output("Examining available space ...", False) if free_space(dirname) <= size: - raise FatalError('Not enough space under %s to host the image' % - dirname) + raise FatalError("Not enough space under %s to host the temporary " + "image" % dirname) self.out.success("sufficient") self._create_filesystems(image, partitions)