The tasks of an orchestrator

So, what are the tasks that we expect an orchestrator worth its money to execute for us? Let’s look at them in detail. The following list shows the most important tasks that, at the time of writing, enterprise users typically expect from their orchestrator.

Reconciling the desired state

When using an orchestrator, you tell it, preferably in a declarative way, how you want it to run a given application or application service. We learned what declarative versus imperative means in Chapter 11, Managing Container with Docker Compose. Part of this declarative way of describing the application service that we want to run includes elements such as which container image to use, how many instances of this service to run, which ports to open, and more. This declaration of the properties of our application service is what we call the desired state.

So, when we now tell the orchestrator to create a new application service based on the declaration for...