#!/bin/bash

# Copyright (C) 2016 Red Hat, Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

set -euo pipefail
IFS=$'\n\t'

# This is a small wrapper script that automatically fetches
# the storage options from the docker-storage sysconfig file
# and passes them to the migrator.
#
# The script supports both in-container runs and direct
# invocation.

MIGRATOR=/usr/bin/v1.10-migrator-local
STORAGE_FILE=/etc/sysconfig/docker-storage
GRAPH=/var/lib/docker

main() {

	# are we in a container?
	if [[ -n ${container-} ]]; then

		if [[ ! -d /host ]]; then
			echo "ERROR: Running inside a container, but /host not mounted." >&2
			exit 1
		fi

		cp "$MIGRATOR" /host/tmp
		MIGRATOR="chroot /host /tmp/$(basename $MIGRATOR)"
		STORAGE_FILE=/host${STORAGE_FILE}
	fi

	if [ ! -d "$GRAPH" ]; then
		echo "ERROR: Cannot find docker root dir at \"$GRAPH\"." >&2
		exit 1
	fi

	# load storage opts if we can find the file
	local storage_opts=
	if [ -r "$STORAGE_FILE" ] && grep -q -E '^DOCKER_STORAGE_OPTIONS\s*=' "$STORAGE_FILE"; then
		storage_opts=$(sed -n -e 's/^DOCKER_STORAGE_OPTIONS\s*=\s*// p' "$STORAGE_FILE")
		storage_opts=${storage_opts#\"}
		storage_opts=${storage_opts%\"}
	fi

	CMD="$MIGRATOR --graph $GRAPH $storage_opts"
	echo "RUNNING: $CMD"
	eval $CMD
}

main "$@"