cmd/go: allow serving module under the subdirectory of git repository

[nhooyr]

If you head to https://github.com/nhooyr/websocket presently, you'll get blasted with a massive root directory listing, mostly due to all the Go files. It's obnoxious.

Compare that to https://github.com/nhooyr/websocket/tree/067b40e227d0d6af9e399c1efe0dd80efae1b79f where the Go module has been moved to the subdirectory ./mod inside the repository.
See nhooyr/websocket#136

So I want to move the Go module to the subdirectory ./mod inside the repository and serve that subdirectory for the nhooyr.io/websocket import path but it doesn't look like there is an easy way to do that.

The go-import meta tag only allows me to specify the import path of the repository, which in this case would make it nhooyr.io/websocket/mod which is nasty. I want to serve the subdirectory directly under nhooyr.io/websocket. Looks like I can do this with the new mod vcs to the go-import tag but then I have to run my own module server which I want to ideally avoid.

Is this something that would be considered or is already possible?

[nhooyr]

For now I'm redirecting go get to https://github.com/nhooyr/websocket-mod where I've moved the module to the root of the repository. Unideal for sure but works well for now.

[nhooyr]

I might also just switch to moving the real code into the subdir mod but have a package in the root that uses type aliases to alias directly to the mod subpkg. Would involve some duplicate code and be harder to maintain though.

[nhooyr]

So unfortunately people were getting confused that the mod path didn't resolve directly to the root of the repo and I tried the type alias thing but in the docs it links directly to the other package instead of inlining the docs so I'd have a decent amount of duplication if I copied the types and translated between them.

[katiehockman]

It's unclear what bug is being raised in this issue and/or what proposal to the go command is being suggested. I'm going to close this bug, but check out https://github.com/golang/go/wiki/Questions as it may provide a good avenue to continue this discussion.

[nhooyr]

Apologies for the confusion. To clarify, I'm trying to serve a subdir of my repository https://github.com/nhooyr/websocket under the import path nhooyr.io/websocket but this doesn't seem feasible with the current tooling without my own module proxy and event then GoDoc wouldn't work as it doesn't support modules yet.

[nejtr0n]

I've got same issue. I have project with migrations, protobuf files and other infrastracture files.
So I decide to put my project under
https://vcs/vendor/project/src/.
But i could not import in go modules.

[jwinnie]

I have the same issue. @katiehockman Please reopen, this is a legitimate issue that a lot of people are experiencing.

A brief proposal to fix the issue would be to add an optional fourth parameter to go-import, so if you wanted to specify a subdirectory you could do something like this:

<meta name="go-import" content="nhooyr.io/websocket git https://github.com/nhooyr/websocket mod">

This would import the mod subdirectory of the github.com/nhooyr/websocket git repository.

[katiehockman]

/cc @bcmills @jayconrod

[bcmills]

See previously #33562.