123 lines
4.8 KiB
Python
123 lines
4.8 KiB
Python
# Copyright [2010] [Anso Labs, LLC]
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations 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.exception import Error
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from nova.utils import execute
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def partition(infile, outfile, local_bytes=0, local_type='ext2'):
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"""Takes a single partition represented by infile and writes a bootable drive image into 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 formatted as ext2.
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In the diagram below, dashes represent drive sectors.
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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 file_size % sector_size != 0:
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logging.warn("Input partition size not evenly divisible by 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 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 # c
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local_first = primary_last + 1 # d
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local_last = local_first + local_sectors # 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' % (outfile, last_sector, sector_size))
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# make mbr partition
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execute('parted --script %s mklabel msdos' % outfile)
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# make primary partition
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execute('parted --script %s mkpart primary %ds %ds' % (outfile, primary_first, primary_last))
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# make local partition
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if local_bytes > 0:
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execute('parted --script %s mkpartfs primary %s %ds %ds' % (outfile, local_type, local_first, local_last))
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# copy file into partition
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execute('dd if=%s of=%s bs=%d seek=%d conv=notrunc,fsync' % (infile, outfile, sector_size, primary_first))
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def inject_key(key, image, partition=None):
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"""Injects a ssh key into a disk image.
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It adds the specified key to /root/.ssh/authorized_keys
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it will mount the image as a fully partitioned disk and attempt to inject 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 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 Error('Failed to load partition: %s' % err)
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mapped_device = '/dev/mapper/%sp%s' % ( device.split('/')[-1] , 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('sudo mount %s %s' % (mapped_device, tmpdir))
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if err:
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raise Error('Failed to mount filesystem: %s' % err)
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try:
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# inject key file
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_inject_into_fs(key, tmpdir)
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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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os.rmdir(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_into_fs(key, fs):
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sshdir = os.path.join(os.path.join(fs, 'root'), '.ssh')
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execute('sudo mkdir %s' % sshdir) #error on 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 bash -c "cat >> %s"' % keyfile, '\n' + key + '\n')
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