Re-use cache_url() in fedora element.

The fedora element downloads images too, so we should re-use the caching
code from the ubuntu element.

There doesn't seem to be other examples of code shared between root.d
scripts. In the fedora and dpkg elements we copy install-packages into
the chroot, but that model doesn't apply when we're running scripts
outside of the chroot. Seems sane to just run it directly from the bin/
dir in the temporary hooks directory.

Change-Id: Iaa6aca660042fea323cab4271633a4bdbbc271b8

elements/cache-url/README.md

@@ -0,0 +1 @@
+A helper script to download images into a local cache.

elements/cache-url/bin/cache-url

@@ -0,0 +1,48 @@
+#!/bin/sh
+
+# Copyright 2012 Hewlett-Packard Development Company, L.P.
+# All Rights Reserved.
+# Copyright 2013 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+set -e
+
+# Download a URL to a local cache
+# e.g. cache-url http://.../foo ~/.cache/image-create/foo
+
+url=$1
+dest=$2
+
+mkdir -p $(dirname $dest)
+tmp=$(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
+    exit 1
+fi

elements/fedora/element-deps

@@ -1,2 +1,3 @@
 dib-run-parts
 dracut-network
+cache-url

elements/fedora/root.d/10-fedora-cloud-image

@@ -15,14 +15,11 @@ DIB_RELEASE=${DIB_RELEASE:-Fedora18}
 BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-$DIB_RELEASE-Cloud-$ARCH-latest.qcow2}
 BASE_IMAGE_TAR=$DIB_RELEASE-Cloud-$ARCH-latest.tgz
 
-mkdir -p $IMG_PATH
-# TODO: don't cache forever.
-if [ ! -f $IMG_PATH/$BASE_IMAGE_FILE ] ; then
-   echo "Fetching Base Image"
-   wget $DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE -O $IMG_PATH/$BASE_IMAGE_FILE.tmp
-   mv $IMG_PATH/$BASE_IMAGE_FILE.tmp $IMG_PATH/$BASE_IMAGE_FILE
-fi
-if [ ! -f $IMG_PATH/$BASE_IMAGE_TAR ] ; then
+echo "Fetching Base Image"
+$TMP_HOOKS_PATH/bin/cache-url $DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE $IMG_PATH/$BASE_IMAGE_FILE
+
+if [ ! -f $IMG_PATH/$BASE_IMAGE_TAR -o \
+    $IMG_PATH/$BASE_IMAGE_FILE -nt $IMG_PATH/$BASE_IMAGE_TAR ] ; then
     echo "Repacking base image as tarball."
     WORKING=$(mktemp -d)
     EACTION="rm -r $WORKING"

elements/ubuntu/element-deps

@@ -1,2 +1,3 @@
 dpkg
 dib-run-parts
+cache-url

elements/ubuntu/root.d/10-cache-ubuntu-tarball

@@ -14,39 +14,9 @@ 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
+$TMP_HOOKS_PATH/bin/cache-url $SHA256SUMS $IMG_PATH/SHA256SUMS.ubuntu.$DIB_RELEASE.$ARCH
+$TMP_HOOKS_PATH/bin/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