Has anyone successfully been able to connect ER/Studio to MariaDB in RDS to forward/reverse engineer? I thought maybe this would be possible with an ODBC connection.
I haven't tried MariaDB on RDS specifically .. but I have managed to connect to and reverse-engineer a *MySQL* database running on RDS. This was done by downloading the MySQL ODBC drivers, and then using the ODBC Data Source Administrator to create a User DSN connection - this will prompt you for the driver to use, and here you can select the Unicode or ANSI MySQL ODBC driver and then click on Finish .. you'll then need to specify the Connection Parameters (hostname, credentials) in a new window.
NOTE though there I did encounter what appears to be a bug when reverse-engineering a database that might contain object name that are MySQL reserved words eg table `group`. A temporary workaround here is de-select such object names and proceed with the reverse engineering, but a better solution would be to connect to the RDS instance and extract the DDL via mysqldump --no-data --triggers --routines .. modify the resulting DDL to rename such objects .. and then create the db on your local environment .. and then reverse-engineer from your local environment.