Lower folder for composer? (and Laravel)

[EliW]

So I was needing a better deployment method than the manual process we were using on this one contract. And instead of writing my own shell script like I usually do, decided to give Deployer a go. I ended up struggling with a few issues in the beginning (didn't have ACL installed, use deploy-keys and unique hostname/alias for github that I had to understand how to get deployer to understand, etc)

But then I ran into a bigger issue and I couldn't figure out how to handle this from the docs.

Basically, in this repo, the actual PHP project sits 'one level down' in the path. And that's where the composer.json is (and where some other tasks like npm run prod will need to be run from).

But Deployer assumes that my composer config is at the top level.

So how do I tell Deployer that after checkout out the repo, that it needs to actually change directory down a level into an appname folder, before running composer install, as well as any number of subsequent artisan/npm/etc commands it might need to run?

[EliW]

Found the answer but only after digging deeply in the docs ... feels like this should be a top level "how to make this work" because it's so common:

config:
  sub_directory: application/