X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/10a5c2bf01f0a40935fce4ee9dd2704c139bac93..88f83027df65608a70e1a88f96b4a3055427dd52:/image_creator/bundle_volume.py diff --git a/image_creator/bundle_volume.py b/image_creator/bundle_volume.py index ff6ed3e..c4cc83c 100644 --- a/image_creator/bundle_volume.py +++ b/image_creator/bundle_volume.py @@ -92,6 +92,7 @@ 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 +107,7 @@ 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 +115,14 @@ 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 +133,10 @@ 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 +148,9 @@ 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 +168,7 @@ 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 +183,10 @@ 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 +231,13 @@ 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 +255,7 @@ 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: @@ -254,13 +268,14 @@ 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: absmpoint = os.path.abspath(target + mpoint) @@ -269,6 +284,8 @@ class BundleVolume(object): 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 +296,10 @@ 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 +335,9 @@ 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', @@ -339,6 +363,10 @@ 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 = {} for p in self.disk.partitions: @@ -376,15 +404,15 @@ class BundleVolume(object): target = tempfile.mkdtemp() try: - absmpoints = self._mount(target, - [(mapped[i], filesystem[i].mpoint) - for i in mapped.keys()]) + self._mount( + target, + [(mapped[i], filesystem[i].mpoint) for i in mapped.keys()]) + 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() @@ -397,9 +425,21 @@ class BundleVolume(object): for excl in excluded: dirname = os.path.dirname(excl) stat = os.stat(dirname) - os.mkdir(target + excl, stat.st_mode) + 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 # systems that have been recreated. @@ -451,8 +491,8 @@ 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)