Auto-down CLI Flag/Setting

Describe the Feature You Want

I'd like an option so an interrupt to tilt up automatically invokes tilt down.

Perhaps something like:

$ tilt up --auto-down

(And also an option to make this the project- and/or system-wide default so the user doesn't need to specify it each time.)

Current Behavior

Even after tilt up is killed, there are a bunch of running Docker containers (at least when using the docker_compose directive.)

Why Do You Want This?

My laptop battery has been draining quickly because I didn't realize/expect tilt to require me to run tilt down (or the more extreme docker ps -q | xargs docker rm -f) until a few days into using tilt.

Our Tilt stack is cheap/quick to bring up fresh, but expensive to keep running in the background so if you're done with development on Tilt managed services for the day, it's nice to not have docker wasting resources in the background, and—we're human—so it's easy to forget to run down while it's easy to remember to kill an open terminal window.

This is by no means a blocker, but would definitely be nice! ❤️🎉

Start at the tilt up and tilt down CLI entry points, then trace how the docker_compose directive manages containers and how project or system settings are loaded. Done means an interrupt to tilt up can trigger cleanup, with the requested command-line and default-setting behavior defined and verified.