Docker container on linux authentication

Question

We have docker containers running on Linux EC2 instances, bastion forwards the user to the container. User authentication happens via centrify and users who has access to Ec2 can only login to the container.

Is there a way by which we can block user directly accessing the ec2 but has access only to the container running on it ?

Appreciate any suggestion also please let me know for any further information.

Thanks, Karthik