diskimage-builder/diskimage_builder/elements/cache-url/bin/cache-url
Ian Wienand 97c01e48ed Move elements & lib relative to diskimage_builder package
Currently we have all our elements and library files in a top-level
directory and install them into
<root>/share/diskimage-builder/[elements|lib] (where root is either /
or the root of a virtualenv).

The problem with this is that editable/development installs (pip -e)
do *not* install data_files.  Thus we have no canonical location to
look for elements -- leading to the various odd things we do such as a
whole bunch of guessing at the top of disk-image-create and having a
special test-loader in tests/test_elements.py so we can run python
unit tests on those elements that have it.

data_files is really the wrong thing to use for what are essentially
assets of the program.  data_files install works well for things like
config-files, init.d files or dropping documentation files.

By moving the elements under the diskimage_builder package, we always
know where they are relative to where we import from.  In fact,
pkg_resources has an api for this which we wrap in the new
diskimage_builder/paths.py helper [1].

We use this helper to find the correct path in the couple of places we
need to find the base-elements dir, and for the paths to import the
library shell functions.

Elements such as svc-map and pkg-map include python unit-tests, which
we do not need tests/test_elements.py to special-case load any more.
They just get found automatically by the normal subunit loader.

I have a follow-on change (I69ca3d26fede0506a6353c077c69f735c8d84d28)
to move disk-image-create to a regular python entry-point.

Unfortunately, this has to move to work with setuptools.  You'd think
a symlink under diskimage_builder/[elements|lib] would work, but it
doesn't.

[1] this API handles stuff like getting files out of .zip archive
modules, which we don't do.  Essentially for us it's returning
__file__.

Change-Id: I5e3e3c97f385b1a4ff2031a161a55b231895df5b
2016-11-01 17:27:41 -07:00

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#!/bin/bash
# Copyright 2012 Hewlett-Packard Development Company, L.P.
# 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.
if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
set -x
fi
set -eu
set -o pipefail
# Download a URL to a local cache
# e.g. cache-url http://.../foo ~/.cache/image-create/foo
SCRIPT_NAME=$(basename $0)
SCRIPT_HOME=$(dirname $0)
FORCE_REVALIDATE=0
function show_options () {
echo "Usage: $SCRIPT_NAME [options] <url> <destination_file>"
echo
echo "Download a URL and cache it to a specified location."
echo "Subsequent requests will compare the last modified date"
echo "of the upstream file to determine whether it needs to be"
echo "downloaded again."
echo
echo "Options:"
echo " -f -- force upstream caches to fetch a new copy of the file"
echo " -h -- show this help"
echo
exit $1
}
TEMP=$(getopt -o hf -n $SCRIPT_NAME -- "$@")
if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
# Note the quotes around `$TEMP': they are essential!
eval set -- "$TEMP"
while true ; do
case "$1" in
-h|"-?") show_options 0;;
-f) FORCE_REVALIDATE=1; shift 1;;
--) shift; break;;
*) echo "Error: unsupported option $1." ; exit 1 ;;
esac
done
url=$1
dest=$2
time_cond=
curl_opts=""
if [ -z $url -o -z $dest ] ; then
show_options 1
fi
if [ -p $dest ]; then
type="fifo"
tmp=$(mktemp --tmpdir download.XXXXXXXX)
else
type="normal"
mkdir -p $(dirname $dest)
tmp=$(mktemp $(dirname $dest)/.download.XXXXXXXX)
fi
if [ "$FORCE_REVALIDATE" = "1" ]; then
curl_opts="-H 'Pragma: no-cache, must-revalidate' -H 'Cache-Control: no-cache, must-revalidate'"
success="Downloaded and cached $url, having forced upstream caches to revalidate"
elif [ -f $dest -a -s $dest ] ; then
time_cond="-z $dest"
success="Server copy has changed. Using server version of $url"
else
success="Downloaded and cached $url for the first time"
fi
rcode=$(eval curl -v -L -o $tmp -w '%{http_code}' $curl_opts $url $time_cond)
if [ "$rcode" == "200" -o "${url:0:7}" == "file://" ] ; then
# In cases where servers ignore the Modified time,
# curl cancels the download, outputs a 200 and leaves
# the output file untouched, we don't want this empty file.
if [ -n "$time_cond" -a ! -s $tmp ] ; then
echo "Ignoring empty file returned by curl. Using locally cached $url"
rm -f $tmp
else
echo $success
if [ "fifo" = "$type" ]; then
cp $tmp $dest
rm $tmp
else
mv $tmp $dest
fi
fi
# 213 is the response to a ftp MDTM command, curl outputs a 213 as the status
# if the url redirected to a ftp server and Not-Modified
elif [ "$rcode" = "304" -o "$rcode" = "213" ] ; 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 $tmp
# expose some error codes so the calling process might know what happened
if [ "$rcode" = "404" ] ; then
exit 44
fi
exit 1
fi