Instances and clusters

- [Instructor] Now that we've seen ECS in action…and got a chance to see what it does,…let's take a moment to go back…and talk about the theory behind…how it works and what it does.…ECS as a service, is vaguely divided…into two halves.…There's places to run things,…and things to run.…So let's talk about that first part.…It generally consists of instances and clusters.…ECS works on top of AWS.…It uses the rest of the Amazon web service…to build itself.…

So you run your instances, and those instances…connect to the AWS service called ECS.…And basically ask it for instructions.…You run your instances that run Docker containers…and you run an agent on those.…A little program that every time it starts,…connects to the AWS service and says,…"Do you have any commands for me?…"Any work to do?"…That agent is what makes an instance part of a cluster.…Remember that instances join clusters.…

So let's talk a little bit more about that instance.…It's a program which calls home to wait for instructions.…Those instructions might be something like…