diskimage-builder/elements/redhat-common/bin/extract-image
Pino Toscano f35aace69f Use shorter temporary file names for kpartx
The loopback handling in the Linux kernel limits the filenames of
files associated to loopback devices, see also linux/loop.h.
This is reflected also on userspace, as kpartx will silently do nothing
(exiting with 0) when requesting to remove a filename longer than 64
characters, as that name will obviously not match the truncated
filename. The result of this is that, when extracting qcow2 images for
the first time, if the qcow2 filename is long enough then the loopback
device will not be removed, remaining as stale in the host.

As a workaround, use a temporary file name when convering a qcow2 image
to raw, instead of using the base name of the qcow2 file.
While this still will not fix the issue when manually using a long
temporary directory (e.g. TMP_DIR=/very/long/etc...), at least should
avoid it in other cases.

Change-Id: Ibf46cd313a9d89412c0e1068fa0993be6c5a29db
2015-04-21 10:36:33 +02:00

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Executable File

#!/bin/bash
# Intended to be called from the root.d cloud-image script as follows:
# $TMP_HOOKS_PATH/bin/extract-image $BASE_IMAGE_FILE $BASE_IMAGE_TAR $IMAGE_LOCATION $CACHED_IMAGE
if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
set -x
fi
set -eu
set -o pipefail
BASE_IMAGE_FILE=$1
BASE_IMAGE_TAR=$2
IMAGE_LOCATION=$3
CACHED_IMAGE=$4
CACHED_TAR=$DIB_IMAGE_CACHE/$BASE_IMAGE_TAR
DIB_LOCAL_IMAGE=${DIB_LOCAL_IMAGE:-""}
TAR_LOCK=$CACHED_TAR.lock
function extract_image() {
if [ -n "$DIB_OFFLINE" -a -f "$CACHED_TAR" ] ; then
echo "Not checking freshness of cached $CACHED_TAR."
else
if [ -z "$DIB_LOCAL_IMAGE" ]; then
echo "Fetching Base Image"
# There seems to be some bad Fedora mirrors returning http 404's for the cloud image.
# If the image fails to download due to a 404 we retry once.
set +e
$TMP_HOOKS_PATH/bin/cache-url $IMAGE_LOCATION $CACHED_IMAGE
RV=$?
set -e
if [ "$RV" == "44" ] ; then
$TMP_HOOKS_PATH/bin/cache-url $IMAGE_LOCATION $CACHED_IMAGE
elif [ "$RV" != "0" ] ; then
exit 1
fi
fi
if [ ! -f $CACHED_TAR -o \
$CACHED_IMAGE -nt $CACHED_TAR ] ; then
echo "Repacking base image as tarball."
WORKING=$(mktemp --tmpdir=${TMP_DIR:-/tmp} -d)
EACTION="rm -r $WORKING"
trap "$EACTION" EXIT
echo "Working in $WORKING"
RAW_FILE=$(mktemp --tmpdir=$WORKING XXXXXX.raw)
qemu-img convert -f qcow2 -O raw $CACHED_IMAGE $RAW_FILE
ROOT_PARTITON=p$(sudo kpartx -l $RAW_FILE | awk "/loop[0-9]+p/"|wc -l)
sudo udevadm settle
# kpartx fails if no /dev/loop* exists, "losetup -f" prints first unused
# loop device and creates it if it doesn't exist
sudo losetup -f
# XXX: Parsing stdout is dangerous, would like a better way to discover
# the device used for the image.
ROOT_LOOPDEV=$(sudo kpartx -av $RAW_FILE | \
awk "/loop[0-9]+$ROOT_PARTITON/ {print \$3}")
# If running inside Docker, make our nodes manually, because udev will not be working.
if [ -f /.dockerenv ]; then
sudo dmsetup --noudevsync mknodes
fi
if ! timeout 5 sh -c "while ! [ -e /dev/mapper/$ROOT_LOOPDEV ]; do sleep 1; done"; then
echo "Error: Could not find /dev/mapper/$ROOT_LOOPDEV"
exit 1
fi
EACTION="sudo kpartx -d $RAW_FILE ; $EACTION"
trap "$EACTION" EXIT
mkdir $WORKING/mnt
sudo mount /dev/mapper/$ROOT_LOOPDEV $WORKING/mnt
EACTION="sudo umount -f $WORKING/mnt ; $EACTION"
trap "$EACTION" EXIT
# find out if chroot tar has full xattr support
if [ 0 == `sudo chroot $WORKING/mnt bin/tar --help | grep -c xattrs-exclude` ]; then
TAROPTS="--no-xattrs"
else
TAROPTS="--xattrs --xattrs-include='*' --xattrs-exclude='security.selinux'"
fi
# Chroot in so that we get the correct uid/gid
sudo chroot $WORKING/mnt bin/tar $TAROPTS -cz . > $WORKING/tmp.tar
mv $WORKING/tmp.tar $CACHED_TAR
else
echo "Using cached tar from $CACHED_TAR"
fi
fi
# Extract the base image (use --numeric-owner to avoid UID/GID mismatch between
# image tarball and host OS e.g. when building Fedora image on an openSUSE host)
# Include all xattrs except selinux because the selinux ones cause issues in our
# chroot environment, and we restore all of those at the end of the build anyway.
echo "Extracting base root image from $CACHED_TAR"
sudo tar -C $TARGET_ROOT --numeric-owner --xattrs --xattrs-include='*' --xattrs-exclude='security.selinux' -xzf $CACHED_TAR
}
(
echo "Getting $TAR_LOCK: $(date)"
# Wait up to 20 minutes for another process to download
if ! flock -w 1200 9 ; then
echo "Did not get $TAR_LOCK: $(date)"
exit 1
fi
extract_image
) 9> $TAR_LOCK