#!/bin/bash
# @params:
#  1* => docker database running container name
#  2* => directory to place compressed backups when finished
#  3  => (optional) number of backups to keep

## NEEDS packages: cpulimit, docker

set -o allexport
if [[ $1 == '' || $2 == '' ]]; then
	echo 'E| Parameters are incorrect. Please specify "container_name /path/for/backups"'
	exit 1
fi

[[ ! -d $2 ]] && mkdir -p $2

set -e
umask 077
CLIM1=${CPU_LIMIT_DUMP:-70}
CLIM2=${CPU_LIMIT_XZ:-20}
IMGTYPE=$(docker inspect --format='{{.Config.Image}}' $1 | cut -f1 -d:)
[[ $BACKTS == '' ]] && BACKTS=`date +"%Y%m%d"`.`echo $RANDOM|md5sum|head -c8`
TMPDIR=/var/tmp/dumps
mkdir -p $TMPDIR

echo 'docker-db-dump: '$1-$BACKTS

if [[ $IMGTYPE == 'postgres' ]]; then
	docker exec $1 env | grep -i postgres_ > /tmp/.env-docker-db-dump
	source /tmp/.env-docker-db-dump && rm /tmp/.env-docker-db-dump
	DB=${POSTGRES_DB}
	if [[ $DB == '' ]]; then
		DB=${POSTGRES_USER}
	fi
	DBU=''
	if [[ $POSTGRES_USER != '' ]]; then
		DBU='-U'${POSTGRES_USER}
	fi
	echo "nice -n 19 docker exec -upostgres $1 pg_dump $DBU $DB > $TMPDIR/$1.sql" \
		> /tmp/.postgres-docker-db-dump
	cpulimit -q -l $CLIM1 -f -- bash /tmp/.postgres-docker-db-dump
	rm /tmp/.postgres-docker-db-dump

elif [[ $IMGTYPE == 'mariadb' || $IMGTYPE == 'mysql' ]]; then
	cat <<EOLFF > /tmp/.mysql-docker-db-dump
#!/bin/bash
if [[ \$MYSQL_ROOT_PASSWORD != '' ]]; then
  mysqldump -uroot -p\$MYSQL_ROOT_PASSWORD \$MYSQL_DATABASE
else
  mysqldump -u\$MYSQL_USER -p\$MYSQL_PASSWORD \$MYSQL_DATABASE
fi
rm /docker-db-dump.sh
EOLFF
	chmod +x /tmp/.mysql-docker-db-dump
	docker cp /tmp/.mysql-docker-db-dump $1:/docker-db-dump.sh
	echo "nice -n 19 docker exec $1 /docker-db-dump.sh > $TMPDIR/$1.sql" \
		> /tmp/.mysql-docker-db-dump
	cpulimit -l $CLIM1 -f -- bash /tmp/.mysql-docker-db-dump
	rm /tmp/.mysql-docker-db-dump

else
	echo 'FATAL: image not supported "'$IMGTYPE'"'
	exit 2
fi

set -x
cpulimit -l $CLIM2 -f -- nice -n 19 xz -9 $TMPDIR/$1.sql
mv $TMPDIR/$1.sql.xz $2/$BACKTS-$1.sql.xz

cd $2/
if [[ $? == 0 ]]; then
	rmkeep $1.sql.xz ${3:-14} # days to keep by default
fi