both seem to be okay.
can you set host to % for db user in mariadb container?
MariaDB> grant all privileges on `db_name`.* TO 'db_name'@'%' identified by 'db_password';
replace db_name and db_password with ones from site_config.json
refer: https://docs.bitnami.com/aws/infrastructure/mariadb/configuration/create-database/