install command support pass through repositories

[Brianzchen]

Do you want to request a feature or report a bug?
feature

What is the current behavior?
Currently when I run flow-typed install it will always install lib defs from the preconfigured src destination being what's in the cache dir ${homeDir}/.flow-typed. There is an option to target a custom cache dir but most of the time a user of flow-typed wouldn't use that because that tries to pull all lib defs from that particular custom dir.

The copy from src to dest is here

Cache dir query is done here

What is the expected behavior?
What I'd like to see is a bypass source location option where flow-typed can try to first query defs from there before looking in the cache dir which ultimately is pulled from the flow-typed repo.

If this is a feature request, what is motivation or use case for changing the behavior?
This opens up a lot of doors for teams to build their own configs and custom defs that can be easily shared without copying and pasting everywhere.

1. If my company hasn't fully adopted flowtype or uses TS and the maintainers of a private library doesn't want to maintain flow I can still self serve just as flow-typed does for open source libraries
2. I can create type defs to override what's in flow-typed as I wait for PRs to get merged
3. (future thinking) It can be a central place to save other things such as standardised .flowconfig that teams can use in the future when creating new repos and in the future we can enable some kind of flow-typed init command that installs it if they are pulling from a custom source

Doubts

• Not really sure how to configure something like this, maybe just flow-typed install --customDir=~/some-place or it's a config file?
• I guess the alternative is to create a private repo where private type defs are stored and you can just add a line in the [libs] section in .flowconfig that point to it like @node_modules/@scope/private-types

[Brianzchen]

The correct thing here would be to build a proxy for where the cache is generated from, and the cli searches for lib defs there. If they cannot be found then it will search in flow-typed/flow-typed repo.

But digging into the code it doesn't support that because that cache is hardcoded right now to run git pulls to update the cache as well as using the git version to make version signing (though this seem to matter less).
https://github.com/flow-typed/flow-typed/blob/master/cli/src/lib/git.js#L140