diskimage-builder/diskimage_builder/elements/apt-preferences/extra-data.d/99-set-apt-package-pins

#!/bin/bash
#
# Copyright 2014 Hewlett-Packard Development Company, L.P.
#
# 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

# exit directly if DIB_DPKG_MANIFEST is not defined properly
if [ -z "${DIB_DPKG_MANIFEST:-}" ]; then
    echo "DIB_DPKG_MANIFEST must be set to the location of a manifest file you wish to use"
    exit 0
elif [ ! -f "$DIB_DPKG_MANIFEST" -o ! -s "$DIB_DPKG_MANIFEST" ]; then
    echo "$DIB_DPKG_MANIFEST is not a valid manifest file."
    echo "You should assign a proper manifest file in DIB_DPKG_MANIFEST"
    exit 1
fi

DIB_DPKG_MANIFEST=$(readlink -f $DIB_DPKG_MANIFEST)

# Create the preferences file from the given manifest
outfile=$(mktemp)
for package in $(jq -r ".packages[].package" $DIB_DPKG_MANIFEST); do
    version=$(jq -r ".packages[] | select(.package == \"${package}\") |\
        .version" $DIB_DPKG_MANIFEST)
    cat << EOF >> $outfile
Package: ${package}
Pin: version ${version}
Pin-Priority: 1001

EOF
done

if [ -s $outfile ]; then
    sudo mv $outfile $TMP_MOUNT_PATH/etc/apt/preferences
else
    rm $outfile
fi