diskimage-builder/elements/ubuntu-core/root.d/10-cache-ubuntu-image

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#!/bin/bash
# These are useful, or at worst not harmful, for all images we build.
# dib-lint: disable=safe_sudo
if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
set -x
fi
set -eu
set -o pipefail
[ -n "$ARCH" ]
[ -n "$TARGET_ROOT" ]
shopt -s extglob
DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cdimage.ubuntu.com/ubuntu-core/preview}
DIB_RELEASE=${DIB_RELEASE:-alpha-01}
BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-ubuntu-core-$DIB_RELEASE.img}
BASE_IMAGE_TAR=$DIB_RELEASE-ubuntu-core.tgz
SHA256SUMS=${SHA256SUMS:-$DIB_CLOUD_IMAGES/SHA256SUMS}
CACHED_FILE=$DIB_IMAGE_CACHE/$BASE_IMAGE_FILE
CACHED_TAR=$DIB_IMAGE_CACHE/$BASE_IMAGE_TAR
CACHED_SUMS=$DIB_IMAGE_CACHE/SHA256SUMS.ubuntu-core.$DIB_RELEASE
if [ -n "$DIB_OFFLINE" -a -f "$CACHED_TAR" ] ; then
echo "Not checking freshness of cached $CACHED_TAR"
else
echo "Fetching Base Image"
$TMP_HOOKS_PATH/bin/cache-url $SHA256SUMS $CACHED_SUMS
$TMP_HOOKS_PATH/bin/cache-url $DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE $CACHED_FILE
pushd $DIB_IMAGE_CACHE
if ! grep "$BASE_IMAGE_FILE" $CACHED_SUMS | sha256sum --check - ; then
# It is likely that an upstream http(s) proxy has given us a skewed
# result - either a cached SHA file or a cached image. Use cache-busting
# to get (as long as caches are compliant...) fresh files.
# Try the sha256sum first, just in case that is the stale one (avoiding
# downloading the larger image), and then if the sums still fail retry
# the image.
$TMP_HOOKS_PATH/bin/cache-url -f $SHA256SUMS $CACHED_SUMS
if ! grep "$BASE_IMAGE_FILE" $CACHED_SUMS | sha256sum --check - ; then
$TMP_HOOKS_PATH/bin/cache-url -f \
$DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE $CACHED_FILE
grep "$BASE_IMAGE_FILE" $CACHED_SUMS | sha256sum --check -
fi
fi
popd
if [ ! -f $CACHED_TAR -o \
$DIB_IMAGE_CACHE/$BASE_IMAGE_FILE -nt $CACHED_TAR ] ; then
echo "Repacking base image as tarball."
WORKING=$(mktemp -d)
EACTION="rm -r $WORKING"
trap "$EACTION" EXIT
RAW_FILE=$(mktemp --tmpdir=$WORKING XXXXXX.raw)
qemu-img convert -f qcow2 -O raw $CACHED_FILE $RAW_FILE
MAGIC_BIT=p1
# NOTE: On RHEL, partprobe of /dev/loop0 does not create /dev/loop0p2,
# while kpartx at least creates /dev/mapper/loop0p2.
LOOPDEV=$(sudo kpartx -av $RAW_FILE | awk "/loop[0-9]+$MAGIC_BIT/ {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
export LOOPDEV=$LOOPDEV
echo "Loop device is set to: $LOOPDEV"
if ! timeout 5 sh -c "while ! [ -e /dev/mapper/$LOOPDEV ]; do sleep 1; done"; then
echo "Error: Could not find /dev/mapper/$LOOPDEV"
exit 1
fi
EACTION="sudo kpartx -d $RAW_FILE;$EACTION"
trap "$EACTION" EXIT
mkdir $WORKING/mnt
sudo mount /dev/mapper/$LOOPDEV $WORKING/mnt
EACTION="sudo umount -f $WORKING/mnt;$EACTION"
trap "$EACTION" EXIT
# Chroot in so that we get the correct uid/gid
sudo chroot $WORKING/mnt bin/tar -cz . > $WORKING/tmp.tar
mv $WORKING/tmp.tar $DIB_IMAGE_CACHE/$BASE_IMAGE_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 Ubuntu image on an openSUSE host)
sudo tar -C $TARGET_ROOT --numeric-owner -xzf $DIB_IMAGE_CACHE/$BASE_IMAGE_TAR