At the moment, the lifecycle around hooks are pretty basic:

1. pre_build runs before stacker does anything to stacks
2. post_build runs after stack does everything to stacks

It would be nice if hooks were just a part of the dependency graph, like stacks are, so that you can reference outputs from hooks, and use them as inputs to stacks and vice/versa.

For example:

hooks:
  - name: "ecsCluster"
    class_path: stacker.hooks.ecs.create_clusters
    args:
      clusters:
        - "staging"
          
stacks:   
  - name: "app"
    class_path: blueprints.App
    variables:
      ECSCluster: ${hook_data ecsCluster::ClusterName}

Instead of stacker executing the hooks in a separate step, stacker would just execute the hooks as it walks the dependency graph (app depends on ecsCluster).

I'm not even sure if "hooks" would be the right name for this if it was supported, since it'd be more like a pseudo/virtual stack.