How to Configure puppet client without node entry in the puppet master's manifest file?

Question

I have a puppet master server running in a Amazon EC2 instance.

I spawn EC2 instances and setup/configure instances as puppet clients to communicate with the puppet master. I have enabled auto-signing of the certificates.

Can I specify in the puppet client which manifest file to synchronize with ? I do not want to add a node <puppetClient> { .... } entry in the manifest file for each puppet client I spawn in the master.

thanks