diskimage-builder/elements/ubuntu/root.d/10-cache-ubuntu-tarball
Clint Byrum 60a1405eef Use conditional GET to fetch latest ubuntu image.
This also switches to using curl which some people may not have
installed. However, curl is far superior for this type of download.

Change-Id: I7ac5a84b30eb8daad320c082f976931c41a24669
2013-05-03 00:38:31 -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}
cache_url()
{
local url=$1
local dest=$2
local tmp=$(mktemp $(dirname $dest)/.download.XXXXXXXX)
rcode=$(curl -o $tmp -z $dest -w '%{http_code}' $url)
if [ "$rcode" == "200" ] ; then
echo "Server copy has changed. Using server version of $url"
mv $tmp $dest
elif [ "$rcode" == "304" ] ; then
echo "Server copy has not changed. Using locally cached $url"
rm -f $tmp
else
echo "Server returned an unexpected response code. [$rcode]"
rm -f $tmp
return 1
fi
}
mkdir -p $IMG_PATH
echo "Fetching Base Image"
cache_url $SHA256SUMS $IMG_PATH/SHA256SUMS.ubuntu.$DIB_RELEASE.$ARCH
cache_url $DIB_CLOUD_IMAGES/$DIB_RELEASE/current/$BASE_IMAGE_FILE $IMG_PATH/$BASE_IMAGE_FILE
pushd $IMG_PATH
grep "$BASE_IMAGE_FILE" SHA256SUMS.ubuntu.$DIB_RELEASE.$ARCH | sha256sum --check -
popd
# Extract the base image
sudo tar -C $TARGET_ROOT -xzf $IMG_PATH/$BASE_IMAGE_FILE
sudo rmdir $TARGET_ROOT/lost+found