ba4218ea98
Use 4k blocks for the ext4 filesystem. Run fsck on the filesystem to make sure deleted blocks are actually zeroed, and pass -Xbcj to mksquashfs. 4k blocks and -Xbcj decreases the size by 2-6% depending on the filesystem size. Zeroing the blocks of the ext4 fs improves things dramatically. The problem is that DNF downloads the rpms before installing them. In addition to forcing us to use a larger filesystem than we would like it leaves data that is difficult to compress on the image. The downloaded files are removed, but need to be zeroed out so that mksquashfs can compress it.
451 lines
18 KiB
Python
451 lines
18 KiB
Python
# imgutils.py - utility functions/classes for building disk images
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#
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# Copyright (C) 2011-2015 Red Hat, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# Author(s): Will Woods <wwoods@redhat.com>
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import logging
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logger = logging.getLogger("pylorax.imgutils")
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import os, tempfile
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from os.path import join, dirname
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from subprocess import Popen, PIPE, CalledProcessError
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import sys
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import traceback
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import multiprocessing
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from time import sleep
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import shutil
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from pylorax.sysutils import cpfile
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from pylorax.executils import execWithRedirect, execWithCapture
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from pylorax.executils import runcmd, runcmd_output
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######## Functions for making container images (cpio, tar, squashfs) ##########
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def compress(command, rootdir, outfile, compression="xz", compressargs=None):
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'''Make a compressed archive of the given rootdir.
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command is a list of the archiver commands to run
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compression should be "xz", "gzip", "lzma", "bzip2", or None.
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compressargs will be used on the compression commandline.'''
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if compression not in (None, "xz", "gzip", "lzma", "bzip2"):
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raise ValueError("Unknown compression type %s" % compression)
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compressargs = compressargs or ["-9"]
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if compression == "xz":
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compressargs.insert(0, "--check=crc32")
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if compression is None:
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compression = "cat" # this is a little silly
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compressargs = []
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# make compression run with multiple threads if possible
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if compression in ("xz", "lzma"):
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compressargs.insert(0, "-T%d" % multiprocessing.cpu_count())
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elif compression == "gzip":
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compression = "pigz"
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compressargs.insert(0, "-p%d" % multiprocessing.cpu_count())
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elif compression == "bzip2":
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compression = "pbzip2"
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compressargs.insert(0, "-p%d" % multiprocessing.cpu_count())
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logger.debug("find %s -print0 |%s | %s %s > %s", rootdir, " ".join(command),
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compression, " ".join(compressargs), outfile)
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find, archive, comp = None, None, None
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try:
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find = Popen(["find", ".", "-print0"], stdout=PIPE, cwd=rootdir)
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archive = Popen(command, stdin=find.stdout, stdout=PIPE, cwd=rootdir)
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comp = Popen([compression] + compressargs,
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stdin=archive.stdout, stdout=open(outfile, "wb"))
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comp.wait()
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return comp.returncode
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except OSError as e:
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logger.error(e)
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# Kill off any hanging processes
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list(p.kill() for p in (find, archive, comp) if p)
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return 1
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def mkcpio(rootdir, outfile, compression="xz", compressargs=None):
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compressargs = compressargs or ["-9"]
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return compress(["cpio", "--null", "--quiet", "-H", "newc", "-o"],
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rootdir, outfile, compression, compressargs)
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def mktar(rootdir, outfile, compression="xz", compressargs=None, selinux=True):
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compressargs = compressargs or ["-9"]
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tar_cmd = ["tar", "--no-recursion"]
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if selinux:
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tar_cmd += ["--selinux", "--acls", "--xattrs"]
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tar_cmd += ["-cf-", "--null", "-T-"]
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return compress(tar_cmd, rootdir, outfile, compression, compressargs)
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def mksquashfs(rootdir, outfile, compression="default", compressargs=None):
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'''Make a squashfs image containing the given rootdir.'''
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compressargs = compressargs or []
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if compression != "default":
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compressargs = ["-comp", compression] + compressargs
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return execWithRedirect("mksquashfs", [rootdir, outfile] + compressargs)
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def mkrootfsimg(rootdir, outfile, label, size=2, sysroot=""):
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"""
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Make rootfs image from a directory
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:param str rootdir: Root directory
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:param str outfile: Path of output image file
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:param str label: Filesystem label
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:param int size: Size of the image in GiB, if None computed automatically
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:param str sysroot: path to system (deployment) root relative to physical root
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"""
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if size:
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fssize = size * (1024*1024*1024) # 2GB sparse file compresses down to nothin'
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else:
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fssize = None # Let mkext4img figure out the needed size
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mkext4img(rootdir, outfile, label=label, size=fssize)
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# Reset selinux context on new rootfs
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with LoopDev(outfile) as loopdev:
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with Mount(loopdev) as mnt:
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cmd = [ "setfiles", "-e", "/proc", "-e", "/sys", "-e", "/dev", "-e", "/install",
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"/etc/selinux/targeted/contexts/files/file_contexts", "/"]
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root = join(mnt, sysroot.lstrip("/"))
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runcmd(cmd, root=root)
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######## Utility functions ###############################################
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def mksparse(outfile, size):
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'''use os.ftruncate to create a sparse file of the given size.'''
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fobj = open(outfile, "w")
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os.ftruncate(fobj.fileno(), size)
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def mkqcow2(outfile, size, options=None):
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'''use qemu-img to create a file of the given size.
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options is a list of options passed to qemu-img
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Default format is qcow2, override by passing "-f", fmt
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in options.
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'''
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mkqemu_img(outfile, size, options)
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def mkqemu_img(outfile, size, options=None):
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'''use qemu-img to create a file of the given size.
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options is a list of options passed to qemu-img
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Default format is qcow2, override by passing "-f", fmt
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in options.
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'''
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options = options or []
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if "-f" not in options:
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options.extend(["-f", "qcow2"])
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runcmd(["qemu-img", "create"] + options + [outfile, str(size)])
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def loop_attach(outfile):
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'''Attach a loop device to the given file. Return the loop device name.
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Raises CalledProcessError if losetup fails.'''
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dev = runcmd_output(["losetup", "--find", "--show", outfile])
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return dev.strip()
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def loop_detach(loopdev):
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'''Detach the given loop device. Return False on failure.'''
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return (execWithRedirect("losetup", ["--detach", loopdev]) == 0)
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def get_loop_name(path):
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'''Return the loop device associated with the path.
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Raises RuntimeError if more than one loop is associated'''
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buf = runcmd_output(["losetup", "-j", path])
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if len(buf.splitlines()) > 1:
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# there should never be more than one loop device listed
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raise RuntimeError("multiple loops associated with %s" % path)
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name = os.path.basename(buf.split(":")[0])
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return name
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def dm_attach(dev, size, name=None):
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'''Attach a devicemapper device to the given device, with the given size.
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If name is None, a random name will be chosen. Returns the device name.
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raises CalledProcessError if dmsetup fails.'''
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if name is None:
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name = tempfile.mktemp(prefix="lorax.imgutils.", dir="")
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runcmd(["dmsetup", "create", name, "--table",
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"0 %i linear %s 0" % (size/512, dev)])
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return name
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def dm_detach(dev):
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'''Detach the named devicemapper device. Returns False if dmsetup fails.'''
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dev = dev.replace("/dev/mapper/", "") # strip prefix, if it's there
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return execWithRedirect("dmsetup", ["remove", dev])
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def mount(dev, opts="", mnt=None):
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'''Mount the given device at the given mountpoint, using the given opts.
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opts should be a comma-separated string of mount options.
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if mnt is none, a temporary directory will be created and its path will be
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returned.
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raises CalledProcessError if mount fails.'''
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if mnt is None:
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mnt = tempfile.mkdtemp(prefix="lorax.imgutils.")
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logger.debug("make tmp mountdir %s", mnt)
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cmd = ["mount"]
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if opts:
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cmd += ["-o", opts]
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cmd += [dev, mnt]
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runcmd(cmd)
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return mnt
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def umount(mnt, lazy=False, maxretry=3, retrysleep=1.0):
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'''Unmount the given mountpoint. If lazy is True, do a lazy umount (-l).
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If the mount was a temporary dir created by mount, it will be deleted.
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raises CalledProcessError if umount fails.'''
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cmd = ["umount"]
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if lazy: cmd += ["-l"]
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cmd += [mnt]
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count = 0
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while maxretry > 0:
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try:
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rv = runcmd(cmd)
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except CalledProcessError:
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count += 1
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if count == maxretry:
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raise
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logger.warning("failed to unmount %s. retrying (%d/%d)...",
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mnt, count, maxretry)
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if logger.getEffectiveLevel() <= logging.DEBUG:
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fuser = execWithCapture("fuser", ["-vm", mnt])
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logger.debug("fuser -vm:\n%s\n", fuser)
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sleep(retrysleep)
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else:
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break
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if 'lorax.imgutils' in mnt:
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os.rmdir(mnt)
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logger.debug("remove tmp mountdir %s", mnt)
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return (rv == 0)
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def copytree(src, dest, preserve=True):
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'''Copy a tree of files using cp -a, thus preserving modes, timestamps,
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links, acls, sparse files, xattrs, selinux contexts, etc.
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If preserve is False, uses cp -R (useful for modeless filesystems)
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raises CalledProcessError if copy fails.'''
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logger.debug("copytree %s %s", src, dest)
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cp = ["cp", "-a"] if preserve else ["cp", "-R", "-L"]
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cp += [join(src, "."), os.path.abspath(dest)]
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runcmd(cp)
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def do_grafts(grafts, dest, preserve=True):
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'''Copy each of the items listed in grafts into dest.
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If the key ends with '/' it's assumed to be a directory which should be
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created, otherwise just the leading directories will be created.'''
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for imgpath, filename in grafts.items():
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if imgpath[-1] == '/':
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targetdir = join(dest, imgpath)
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imgpath = imgpath[:-1]
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else:
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targetdir = join(dest, dirname(imgpath))
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if not os.path.isdir(targetdir):
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os.makedirs(targetdir)
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if os.path.isdir(filename):
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copytree(filename, join(dest, imgpath), preserve)
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else:
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cpfile(filename, join(dest, imgpath))
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def round_to_blocks(size, blocksize):
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'''If size isn't a multiple of blocksize, round up to the next multiple'''
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diff = size % blocksize
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if diff or not size:
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size += blocksize - diff
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return size
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# TODO: move filesystem data outside this function
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def estimate_size(rootdir, graft=None, fstype=None, blocksize=4096, overhead=256):
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graft = graft or {}
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getsize = lambda f: os.lstat(f).st_size
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if fstype == "btrfs":
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overhead = 64*1024 # don't worry, it's all sparse
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if fstype == "hfsplus":
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overhead = 200 # hack to deal with two bootloader copies
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if fstype in ("vfat", "msdos"):
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blocksize = 2048
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getsize = lambda f: os.stat(f).st_size # no symlinks, count as copies
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total = overhead*blocksize
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dirlist = list(graft.values())
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if rootdir:
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dirlist.append(rootdir)
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for root in dirlist:
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for top, dirs, files in os.walk(root):
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for f in files + dirs:
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total += round_to_blocks(getsize(join(top,f)), blocksize)
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if fstype == "btrfs":
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total = max(256*1024*1024, total) # btrfs minimum size: 256MB
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return total
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######## Execution contexts - use with the 'with' statement ##############
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class LoopDev(object):
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def __init__(self, filename, size=None):
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self.loopdev = None
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self.filename = filename
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if size:
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mksparse(self.filename, size)
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def __enter__(self):
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self.loopdev = loop_attach(self.filename)
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return self.loopdev
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def __exit__(self, exc_type, exc_value, tracebk):
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loop_detach(self.loopdev)
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class DMDev(object):
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def __init__(self, dev, size, name=None):
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self.mapperdev = None
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(self.dev, self.size, self.name) = (dev, size, name)
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def __enter__(self):
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self.mapperdev = dm_attach(self.dev, self.size, self.name)
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return self.mapperdev
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def __exit__(self, exc_type, exc_value, tracebk):
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dm_detach(self.mapperdev)
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class Mount(object):
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def __init__(self, dev, opts="", mnt=None):
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(self.dev, self.opts, self.mnt) = (dev, opts, mnt)
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def __enter__(self):
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self.mnt = mount(self.dev, self.opts, self.mnt)
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return self.mnt
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def __exit__(self, exc_type, exc_value, tracebk):
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umount(self.mnt)
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class PartitionMount(object):
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""" Mount a partitioned image file using kpartx """
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def __init__(self, disk_img, mount_ok=None, submount=None):
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"""
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:param str disk_img: The full path to a partitioned disk image
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:param mount_ok: A function that is passed the mount point and
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returns True if it should be mounted.
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:param str submount: Directory inside mount_dir to mount at
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If mount_ok is not set it will look for /etc/passwd
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If the partition is found it will be mounted under a temporary
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directory and self.temp_dir set to it. If submount is passed it will be
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created and mounted there instead, with self.mount_dir set to point to
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it. self.mount_dev is set to the loop device, and self.mount_size is
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set to the size of the partition.
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When no subdir is passed self.temp_dir and self.mount_dir will be the same.
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"""
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self.mount_dev = None
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self.mount_size = None
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self.mount_dir = None
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self.disk_img = disk_img
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self.mount_ok = mount_ok
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self.submount = submount
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self.temp_dir = None
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# Default is to mount partition with /etc/passwd
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if not self.mount_ok:
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self.mount_ok = lambda mount_dir: os.path.isfile(mount_dir+"/etc/passwd")
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# Example kpartx output
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# kpartx -p p -v -a /tmp/diskV2DiCW.im
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# add map loop2p1 (253:2): 0 3481600 linear /dev/loop2 2048
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# add map loop2p2 (253:3): 0 614400 linear /dev/loop2 3483648
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kpartx_output = runcmd_output(["kpartx", "-v", "-a", "-s", self.disk_img])
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logger.debug(kpartx_output)
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# list of (deviceName, sizeInBytes)
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self.loop_devices = []
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for line in kpartx_output.splitlines():
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# add map loop2p3 (253:4): 0 7139328 linear /dev/loop2 528384
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# 3rd element is size in 512 byte blocks
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if line.startswith("add map "):
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fields = line[8:].split()
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self.loop_devices.append( (fields[0], int(fields[3])*512) )
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def __enter__(self):
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# Mount the device selected by mount_ok, if possible
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self.temp_dir = tempfile.mkdtemp()
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if self.submount:
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mount_dir = os.path.normpath(os.path.sep.join([self.temp_dir, self.submount]))
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os.makedirs(mount_dir, mode=0o755, exist_ok=True)
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else:
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mount_dir = self.temp_dir
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for dev, size in self.loop_devices:
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try:
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mount( "/dev/mapper/"+dev, mnt=mount_dir )
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if self.mount_ok(mount_dir):
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self.mount_dir = mount_dir
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self.mount_dev = dev
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self.mount_size = size
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break
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umount( mount_dir )
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except CalledProcessError:
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logger.debug(traceback.format_exc())
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if self.mount_dir:
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logger.info("Partition mounted on %s size=%s", self.mount_dir, self.mount_size)
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else:
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logger.debug("Unable to mount anything from %s", self.disk_img)
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os.rmdir(self.temp_dir)
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self.temp_dir = None
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return self
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def __exit__(self, exc_type, exc_value, tracebk):
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if self.temp_dir:
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umount(self.mount_dir)
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shutil.rmtree(self.temp_dir)
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self.mount_dir = None
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self.temp_dir = None
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execWithRedirect("kpartx", ["-d", "-s", self.disk_img])
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######## Functions for making filesystem images ##########################
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def mkfsimage(fstype, rootdir, outfile, size=None, mkfsargs=None, mountargs="", graft=None):
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'''Generic filesystem image creation function.
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fstype should be a filesystem type - "mkfs.${fstype}" must exist.
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graft should be a dict: {"some/path/in/image": "local/file/or/dir"};
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if the path ends with a '/' it's assumed to be a directory.
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Will raise CalledProcessError if something goes wrong.'''
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mkfsargs = mkfsargs or []
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graft = graft or {}
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preserve = (fstype not in ("msdos", "vfat"))
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if not size:
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size = estimate_size(rootdir, graft, fstype)
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with LoopDev(outfile, size) as loopdev:
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try:
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runcmd(["mkfs.%s" % fstype] + mkfsargs + [loopdev])
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except CalledProcessError as e:
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logger.error("mkfs exited with a non-zero return code: %d", e.returncode)
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logger.error(e.output)
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sys.exit(e.returncode)
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with Mount(loopdev, mountargs) as mnt:
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if rootdir:
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copytree(rootdir, mnt, preserve)
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do_grafts(graft, mnt, preserve)
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# Make absolutely sure that the data has been written
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runcmd(["sync"])
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# convenience functions with useful defaults
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def mkdosimg(rootdir, outfile, size=None, label="", mountargs="shortname=winnt,umask=0077", graft=None):
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graft = graft or {}
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mkfsimage("msdos", rootdir, outfile, size, mountargs=mountargs,
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mkfsargs=["-n", label], graft=graft)
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def mkext4img(rootdir, outfile, size=None, label="", mountargs="", graft=None):
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graft = graft or {}
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mkfsimage("ext4", rootdir, outfile, size, mountargs=mountargs,
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mkfsargs=["-L", label, "-b", "4096", "-m", "0"], graft=graft)
|
|
|
|
def mkbtrfsimg(rootdir, outfile, size=None, label="", mountargs="", graft=None):
|
|
graft = graft or {}
|
|
mkfsimage("btrfs", rootdir, outfile, size, mountargs=mountargs,
|
|
mkfsargs=["-L", label], graft=graft)
|
|
|
|
def mkhfsimg(rootdir, outfile, size=None, label="", mountargs="", graft=None):
|
|
graft = graft or {}
|
|
mkfsimage("hfsplus", rootdir, outfile, size, mountargs=mountargs,
|
|
mkfsargs=["-v", label], graft=graft)
|