I am trying to configure my RDS Security Group configurations to be able to allow my EC2 instance to read and write to the database, but only admin access the DB via login credentials. Will my setup below achieve this? Should the admin access only happen via SSH?
EC2 setup:
RDS setup (Connected to the EC2 security group name):
Security groups restrict network connections only, and are not related to authentication methods like username/password. Also, since RDS is a managed service you do not get SSH access to the RDS servers.
You've configured the security groups correctly to allow your EC2 server to connect to your RDS server. You just need to remove the SSH rule from the RDS security group since it is of no use.
To configure authentication methods for your MySQL database you need to start by reading the documentation here. In general, you will be using a username/password for all connections to the database.