diskimage-builder/elements/ubuntu/root.d/10-cache-ubuntu-tarball
Mark McLoughlin efb1f435d4 Improve first time download of ubuntu images.
If a cached copy of the file doesn't exist, cache_url() passes a
non-existent path to -z/--time-cond and you see this warning:

 Warning: Illegal date format for -z, --timecond (and not a file name).
 Warning: Disabling time condition. See curl_getdate(3) for valid date syntax.

It works just fine, but the warning is ugly.

Change-Id: Ic6f13a2c596b988308d7fca9cd1745e5d48ae5fb
2013-06-20 00:04:53 +01:00

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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
mkdir -p $(dirname $dest)
local tmp=$(mktemp $(dirname $dest)/.download.XXXXXXXX)
if [ -f $dest ] ; then
time_cond="-z $dest"
success="Server copy has changed. Using server version of $url"
else
success="Downloaded and cached $url for the first time"
fi
rcode=$(curl -o $tmp -w '%{http_code}' $url $time_cond)
if [ "$rcode" == "200" ] ; then
echo $success
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