docker run extension

Describe the Feature You Want

A docker_run extension that makes it easier to run a docker container correctly with 'local_resource'

Why Do You Want This?

We frequently see people use local_resource to run processes on Docker.

Here's an example:
https://github.com/tilt-dev/tilt/issues/4484

Unfortunately, there are mismatches between how local_resource does signal handling and how docker run does signal handling.

In local_resource, Tilt creates a process group. When you stop Tilt (with kill or ctrl-c), Tilt kills the entire process tree. This is basically "container process" semantics.

In docker run, docker leaves it up to the container to determine how to handle external signals and whether to pass signals onto the container.

You can currently work around this by adding your own wrapper script:

function cleanup() {
    docker stop mycontainer
}
trap cleanup SIGINT

but it seems like we should be able to do this with existing APIs and package it up under https://github.com/tilt-dev/tilt-extensions

Related issues:

https://github.com/tilt-dev/tilt/issues/4484
https://github.com/tilt-dev/tilt/issues/4456

Start by reading related issues 4484 and 4456, then review the existing APIs and the tilt-extensions package mentioned in the issue. Define the extension's scope around running Docker containers with local_resource and handling shutdown signals correctly; done means the documented wrapper-script workaround is packaged as a usable docker_run extension.