Fix hardcoded security group ID and suggested improvement for SSL mode handling for RDS

Issue

While running the migration script, I encountered the following error:

An error occurred (InvalidParameterValueException) when calling the CreateReplicationInstance operation: The provided security group identifier or name is invalid. Please verify and provide a valid security group identifier or name.

After some investigation, I found that the script includes a hardcoded SECURITY_GROUP_ID, which is specific to the original author’s AWS environment. This ID will not exist in other users’ accounts and causes the script to fail unless updated manually.

Suggested fix

• Remove the hardcoded SECURITY_GROUP_ID, or
• Allow users to optionally pass in their own security group ID.
• In my testing, omitting the security group entirely worked fine.

Thanks for your work on this project!

P.S. in the docs, you note that users migrating from Neon must use the --tls flag. This is likely true for all RDS users as well. Alternatively, they could set the parameter rds.force_ssl to 0.

Locate the migration script's SECURITY_GROUP_ID definition and the documentation describing the --tls flag. Trace how replication-instance creation receives the security group, then review the RDS SSL guidance. Done means the script no longer depends on the author's account-specific ID, users can supply one if needed, and the documentation accurately explains TLS for RDS.