#!/bin/sh

# Purpose {{{
## Backup data of a Docker container.
## To do that, the script will :
##	Try to stop the corresponding systemd unit (or docker if no related service is found)
##	Make a archive of the container's data to a backup path
##	Restart the container service (or docker.service)
##	Clean old backup
# }}}
# How-to use {{{
## First argument should be the absolut path to the container's data.
##	The data directory and the container should have the same name.
# }}}

# Vars {{{
DEBUG=0

## Nomber of backup to keep
keep_backup="3"

## Manage arguments {{{
## Expect at least 1 argument and 2 maximum
case $# in
	1 )
		## Absolut path to the container data
		ct_data_path="${1}"
		## Absolut path to store the archives.
		## A sub-directory will be created for the container
		docker_backup_path="/mnt/backup/docker"
		;;
	2 )
		ct_data_path="${1}"
		docker_backup_path="${2}"
		;;
	* )
		cat << HELP

container.backup  --
Backup data of a given Docker container.

EXAMPLE :
    - Backup data of FIRST_CT container require the absolut path to data
        container.backup /srv/docker/FIRST_CT
    - Select the directory to store the backup of hello_world container
        container.backup /srv/docker/hello_world /media/usb/docker.backup

HELP

		exit 1
		;;
esac

ct_name=$(basename -- "${ct_data_path}")
docker_data_path=$(dirname -- "${ct_data_path}")
ct_backup_path="${docker_backup_path}/${ct_name}"
## }}}
# }}}

# Tests {{{

## Ensure container data directory exists {{{
if [ ! -d "${ct_data_path}" ]; then
	printf '\e[0;31m%-6s\e[m\n' "Docker data directory doesn't seems available : ${ct_data_path} ."
	exit 1
else
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test arg  — Path to Docker data : ${ct_data_path} ."
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test arg  — Container name to backup : ${ct_name} ."
fi
## }}}
## Ensure backup directory exists {{{
if [ ! -d "${docker_backup_path}" ]; then
	printf '\e[0;31m%-6s\e[m\n' "Backup directory doesn't seems available : ${docker_backup_path} ."
	exit 1
else
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test arg  — Path to store the backup : ${docker_backup_path} ."
fi
## }}}
# }}}

# Get container service name {{{
ct_service_name=$(find /etc/systemd -type f -iname "*${ct_name}*.service" -printf "%f\n")

## If no specific systemd service exists, the docker.service will be used
if [ "${ct_service_name}" = "" ]; then
	ct_service_name="docker.service"
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Service name  — No specific service found for ${ct_name} container, the ${ct_service_name} will be stopped."
else
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Service name  — Service name of ${ct_name} container to stop : ${ct_service_name} ."
fi
# }}}
# Stop the container service {{{
systemctl stop "${ct_service_name}"
[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Service management  — Service ${ct_service_name} was stopped."
# }}}
# Backup container data {{{
## Create the directory to store archive if doesn't already exist
if [ ! -d "${ct_backup_path}" ]; then
	mkdir -p -- "${ct_backup_path}"
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Backup data  — ${ct_backup_path} was created."
fi

## Backup container data
tar czf "${ct_backup_path}/${ct_name}-backup.$(date '+%Y%m%d-%H%M').tar.gz" --directory "${docker_data_path}" "${ct_name}"
[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Backup data  — Data of ${ct_name} container were successfully backuped ${ct_backup_path}/${ct_name}-backup.$(date '+%Y%m%d-%H%M').tar.gz"
# }}}
# Restart the container service {{{
systemctl start "${ct_service_name}"
[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Service management  — Service ${ct_service_name} was started."
# }}}
# Remove old backups {{{
cd -- "${ct_backup_path}" || exit 1
[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Cleaning  — Keep only the ${keep_backup} newest backups."
find . -type f | sort | head -n -"${keep_backup}" | xargs -d '\n' rm -f --
cd -- - > /dev/null || exit 1
# }}}

exit 0