Salt is a great tool for remote execution and configuration management, however you will still need to bootstrap the daemon when spinning up a new node. One option is to create and save a custom AMI, but this creates another resource to maintain and document.
A better method for Linux machines uses Canonical's CloudInit to run a bootstrap script during an EC2 Instance initialization. Cloud-init takes the user_data string passed into a new AWS instance and runs it in a manner similar to rc.local. The bootstrap script needs to:
- Install Salt with dependencies
- Point the minion to the master