docker-mariadb-backup-slave/rootfs/usr/local/bin/healthcheck.sh

#!/bin/bash

MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD:-nopassword}

# slave not configured
SLAVE_STATUS=$(mysql -uroot -p"${MYSQL_ROOT_PASSWORD}" -e 'SHOW SLAVE STATUS\G')
if [[ -z "${SLAVE_STATUS}" ]]; then
    exit 0
fi

# extract slave status
SLAVE_IO=$(echo "${SLAVE_STATUS}" | awk -F: '/Slave_IO_Running/ {gsub(/ /, "", $2); print $2}')
SLAVE_SQL=$(echo "${SLAVE_STATUS}" | awk -F: '/Slave_SQL_Running/ {gsub(/ /, "", $2); print $2}')

# slave ok
if [[ "${SLAVE_IO}" == "Yes" && "${SLAVE_SQL}" == "Yes" ]]; then
    exit 0
fi

# slave not ok
exit 1