Drop support for godep, glide, dep, and buildpack detection by vendor folder

[jameshochadel]

Go modules, Go's official solution to dependency management, have been on by default since Go 1.16. Per the docs and the output I see when running cf push, the buildpack still contains several dependency management solutions that predate modules:

• Godep, archived on Github since 2019
• Glide, not updated since 2019
• dep, deprecated and archived since 2020

Additionally, the buildpack checks for a vendor folder, but go modules does not vendor dependencies by default; instead, it downloads dependencies go $GOPATH/pkg/mod. Vendoring is still possible, but in practice, I see few projects do it.

I propose removing the old dependency management solutions in favor of Go modules, and propose detecting the Go buildpack by checking for the presence of a go.mod file.

[jameshochadel]

👋 Just curious — Would the maintainers accept a PR to add this feature?

[robdimsdale]

I think this is reasonable, and I'd love to drop dead code paths. It would also reduce the surface area we have to test, which would be a benefit to the maintainers, too.

But, I know that CF buildpacks are used by a huge variety of consumers with varying degrees of progression, and I worry that if we drop support for an old vendoring model somewhere down the line this will break our consumers.

[jameshochadel]

Fair enough. Do you know if CF collects any telemetry we could use to help decide whether or not to drop the old methods?