We've just released a new feature that many users will find helpful, the ability to set RDS parameters. You can use this to set common Mysql/MariaDB configuration options required by many apps and CMS's, eg sql_mode. Before you could enter these via the workaround of manually editing the parameter group in AWS, but this isn't ideal as changes made in Idealstack could overwrite these.
To use this feature, edit or create an RDS database instance in your stack, fold open the 'Advanced' section
and enter the parameters one per line