The use case for this is to be able to bring a new server online with an existing kamal deployed setup.

Given I have one web role, one accessory:

servers:
  web:
    host: 123.456.78.9
accessories:
  db:
    host: 123.456.78.9

And I want to add another web server into the mix so servers becomes:

servers:
  web:
    host: 123.456.78.9
  web_new:
    host: 111.222.333.444
accessories:
  db:
    host: 123.456.78.9

To bring the server online you'd need to run kamal setup -r web_new so that it pushes up your env files first but that fails with:

docker stderr: docker: Error response from daemon: Conflict. The container name "/hey-db" is already in use by container "7939d26efb157e547d6a70bf0e713a5ccc9079a016ca8261518dbfd6323da5cc". You have to remove (or rename) that container to be able to reuse that name.

I understand that hey-db has already been provisioned and you can work around this by just running kamal deploy -r web_new after that first failure but I think it probably shouldn't try to setup any accessories since they're not being targeted. In this example the accessory is also on a different host so it's not a host target.

So currently it's:

kamal setup -r web_new
# fails at existing container for accessory
kamal deploy -r web_new
# deploys successfully

Thinking we could adjust so that there's a usable server after the setup command finishes running.