187 lines
6.9 KiB
Python
187 lines
6.9 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Utility methods to resize, repartition, and modify disk images.
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Includes injection of SSH PGP keys into authorized_keys file.
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"""
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import logging
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import os
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import tempfile
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from nova import exception
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from nova import flags
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FLAGS = flags.FLAGS
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flags.DEFINE_integer('minimum_root_size', 1024 * 1024 * 1024 * 10,
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'minimum size in bytes of root partition')
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flags.DEFINE_integer('block_size', 1024 * 1024 * 256,
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'block_size to use for dd')
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def partition(infile, outfile, local_bytes=0, resize=True,
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local_type='ext2', execute=None):
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"""
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Turns a partition (infile) into a bootable drive image (outfile).
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The first 63 sectors (0-62) of the resulting image is a master boot record.
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Infile becomes the first primary partition.
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If local bytes is specified, a second primary partition is created and
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formatted as ext2.
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::
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In the diagram below, dashes represent drive sectors.
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+-----+------. . .-------+------. . .------+
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| 0 a| b c|d e|
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+-----+------. . .-------+------. . .------+
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| mbr | primary partiton | local partition |
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+-----+------. . .-------+------. . .------+
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"""
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sector_size = 512
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file_size = os.path.getsize(infile)
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if resize and file_size < FLAGS.minimum_root_size:
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last_sector = FLAGS.minimum_root_size / sector_size - 1
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execute('dd if=/dev/zero of=%s count=1 seek=%d bs=%d'
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% (infile, last_sector, sector_size))
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execute('e2fsck -fp %s' % infile, check_exit_code=False)
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execute('resize2fs %s' % infile)
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file_size = FLAGS.minimum_root_size
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elif file_size % sector_size != 0:
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logging.warn("Input partition size not evenly divisible by"
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" sector size: %d / %d", file_size, sector_size)
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primary_sectors = file_size / sector_size
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if local_bytes % sector_size != 0:
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logging.warn("Bytes for local storage not evenly divisible"
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" by sector size: %d / %d", local_bytes, sector_size)
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local_sectors = local_bytes / sector_size
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mbr_last = 62 # a
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primary_first = mbr_last + 1 # b
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primary_last = primary_first + primary_sectors - 1 # c
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local_first = primary_last + 1 # d
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local_last = local_first + local_sectors - 1 # e
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last_sector = local_last # e
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# create an empty file
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execute('dd if=/dev/zero of=%s count=1 seek=%d bs=%d'
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% (outfile, mbr_last, sector_size))
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# make mbr partition
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execute('parted --script %s mklabel msdos' % outfile)
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# append primary file
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execute('dd if=%s of=%s bs=%s conv=notrunc,fsync oflag=append'
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% (infile, outfile, FLAGS.block_size))
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# make primary partition
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execute('parted --script %s mkpart primary %ds %ds'
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% (outfile, primary_first, primary_last))
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if local_bytes > 0:
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# make the file bigger
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execute('dd if=/dev/zero of=%s count=1 seek=%d bs=%d'
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% (outfile, last_sector, sector_size))
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# make and format local partition
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execute('parted --script %s mkpartfs primary %s %ds %ds'
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% (outfile, local_type, local_first, local_last))
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def inject_data(image, key=None, net=None, partition=None, execute=None):
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"""Injects a ssh key and optionally net data into a disk image.
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it will mount the image as a fully partitioned disk and attempt to inject
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into the specified partition number.
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If partition is not specified it mounts the image as a single partition.
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"""
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out, err = execute('sudo losetup -f --show %s' % image)
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if err:
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raise exception.Error('Could not attach image to loopback: %s' % err)
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device = out.strip()
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try:
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if not partition is None:
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# create partition
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out, err = execute('sudo kpartx -a %s' % device)
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if err:
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raise exception.Error('Failed to load partition: %s' % err)
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mapped_device = '/dev/mapper/%sp%s' % (device.split('/')[-1],
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partition)
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else:
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mapped_device = device
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out, err = execute('sudo tune2fs -c 0 -i 0 %s' % mapped_device)
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tmpdir = tempfile.mkdtemp()
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try:
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# mount loopback to dir
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out, err = execute(
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'sudo mount %s %s' % (mapped_device, tmpdir))
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if err:
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raise exception.Error('Failed to mount filesystem: %s' % err)
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try:
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if key:
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# inject key file
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_inject_key_into_fs(key, tmpdir, execute=execute)
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if net:
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_inject_net_into_fs(net, tmpdir, execute=execute)
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finally:
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# unmount device
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execute('sudo umount %s' % mapped_device)
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finally:
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# remove temporary directory
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execute('rmdir %s' % tmpdir)
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if not partition is None:
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# remove partitions
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execute('sudo kpartx -d %s' % device)
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finally:
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# remove loopback
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execute('sudo losetup -d %s' % device)
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def _inject_key_into_fs(key, fs, execute=None):
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"""Add the given public ssh key to root's authorized_keys.
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key is an ssh key string.
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fs is the path to the base of the filesystem into which to inject the key.
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"""
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sshdir = os.path.join(os.path.join(fs, 'root'), '.ssh')
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execute('sudo mkdir -p %s' % sshdir) # existing dir doesn't matter
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execute('sudo chown root %s' % sshdir)
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execute('sudo chmod 700 %s' % sshdir)
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keyfile = os.path.join(sshdir, 'authorized_keys')
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execute('sudo tee -a %s' % keyfile, '\n' + key.strip() + '\n')
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def _inject_net_into_fs(net, fs, execute=None):
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"""Inject /etc/network/interfaces into the filesystem rooted at fs.
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net is the contents of /etc/network/interfaces.
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"""
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netdir = os.path.join(os.path.join(fs, 'etc'), 'network')
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execute('sudo mkdir -p %s' % netdir) # existing dir doesn't matter
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execute('sudo chown root:root %s' % netdir)
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execute('sudo chmod 755 %s' % netdir)
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netfile = os.path.join(netdir, 'interfaces')
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execute('sudo tee %s' % netfile, net)
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