mariadb-healthcheck.sh

#!/bin/bash
set -eo pipefail

if [ "$MYSQL_RANDOM_ROOT_PASSWORD" ] && [ -z "$MYSQL_USER" ] && [ -z "$MYSQL_PASSWORD" ]; then
	# there's no way we can guess what the random MySQL password was
	echo >&2 'healthcheck error: cannot determine random root password (and MYSQL_USER and MYSQL_PASSWORD were not set)'
	exit 0
fi

host="$(hostname --ip-address || echo '127.0.0.1')"
user="${MYSQL_USER:-root}"
export MYSQL_PWD="${MYSQL_PASSWORD:-$MYSQL_ROOT_PASSWORD}"

args=(
	# force mysql to not use the local "mysqld.sock" (test "external" connectibility)
	-h"$host"
	-u"$user"
	--silent
)

if select="$(echo 'SELECT 1' | mysql "${args[@]}")" && [ "$select" = '1' ]; then
	exit 0
fi

exit 1