diskimage-builder/elements/ubuntu/root.d/10-cache-ubuntu-tarball
Robert Collins cb62bae9b8 Build images using loopdev instead of qemu-nbd.
Qemu-nbd does not perform well with older versions of qemu due to
the lack of writeback caching mode. It also only builds qcow2 images
and there is a desire for raw image support. Finally, qemu-nbd makes
it very difficult to build images concurrently due to the somewhat
opaque nature of how it selects a /dev/nbd# device. losetup, on
the other hand, makes this process very straight forward.

Change-Id: I309fad8af4fd1e8d1720c17b65e1897a76d5e897
Co-Author: Clint Byrum <clint@fewbar.com>
2013-04-30 08:56:12 -07:00

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#!/bin/bash
# These are useful, or at worst not harmful, for all images we build.
set -e
[ -n "$ARCH" ]
[ -n "$TARGET_ROOT" ]
shopt -s extglob
IMG_PATH=~/.cache/image-create
DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://cloud-images.ubuntu.com/}
DIB_RELEASE=${DIB_RELEASE:-quantal}
BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-$DIB_RELEASE-server-cloudimg-$ARCH-root.tar.gz}
SHA256SUMS=${SHA256SUMS:-https://${DIB_CLOUD_IMAGES##http?(s)://}/$DIB_RELEASE/current/SHA256SUMS}
mkdir -p $IMG_PATH
# TODO: don't cache -current forever.
if [ ! -f $IMG_PATH/$BASE_IMAGE_FILE ] ; then
echo "Fetching Base Image"
wget $SHA256SUMS -O $IMG_PATH/SHA256SUMS.ubuntu.$DIB_RELEASE.$ARCH
wget $DIB_CLOUD_IMAGES/$DIB_RELEASE/current/$BASE_IMAGE_FILE -O $IMG_PATH/$BASE_IMAGE_FILE.tmp
pushd $IMG_PATH
awk "/$BASE_IMAGE_FILE/ { print \$0 \".tmp\" }" SHA256SUMS.ubuntu.$DIB_RELEASE.$ARCH | sha256sum --check -
popd
mv $IMG_PATH/$BASE_IMAGE_FILE.tmp $IMG_PATH/$BASE_IMAGE_FILE
fi
# Extract the base image
sudo tar -C $TARGET_ROOT -xzf $IMG_PATH/$BASE_IMAGE_FILE
sudo rmdir $TARGET_ROOT/lost+found