[checkapi] support diffs

[atoulme]

Add ability to check if the Golang API of a module has changed

[codecov]

Codecov Report

Attention: Patch coverage is 71.97802% with 51 lines in your changes missing coverage. Please review.

Project coverage is 54.82%. Comparing base (7b18318) to head (1488433).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
checkapi/internal/diff.go	64.28%	32 Missing and 13 partials ⚠️
checkapi/main.go	50.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #738      +/-   ##
==========================================
+ Coverage   54.01%   54.82%   +0.80%     
==========================================
  Files          62       64       +2     
  Lines        3806     3987     +181     
==========================================
+ Hits         2056     2186     +130     
- Misses       1555     1591      +36     
- Partials      195      210      +15     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[mx-psi]

Could we do an example PR where we see this output?

[pellared]

What about type parameters (generics)?

[atoulme]

What about type parameters (generics)?

I can add a test using generics, that's not come up yet but should be fun to support.

[atoulme]

@pellared generics peeled off in their own PR here: #739

[atoulme]

Peeling off returning by value in #741

[pellared]

@atoulme, there are some lint failures. Besides, I guess this should be reviewed by OTel Collector approvers. Have you considered using https://pkg.go.dev/golang.org/x/exp/cmd/gorelease?

[atoulme]

Have you considered using https://pkg.go.dev/golang.org/x/exp/cmd/gorelease?

I think we looked at it and it didn't really meet the requirements.

[atoulme]

@open-telemetry/collector-approvers and @open-telemetry/collector-contrib-approvers please review

[mx-psi]

I think this functionality is welcome but I would like to understand why we want to have a custom solution instead of relying in https://pkg.go.dev/golang.org/x/exp/apidiff as Kubernetes does

[atoulme]

I didn't look at that tool. I don't have an opinion on it. Should we prefer it?

[pellared]

I didn't look at that tool. I don't have an opinion on it. Should we prefer it?

This is something which the Go team uses as well. https://pkg.go.dev/golang.org/x/exp/cmd/gorelease uses this package as well. There are still some issues, but I think we should prefer it.

[mx-psi]

I didn't look at that tool. I don't have an opinion on it. Should we prefer it?

I thought it was unmaintained, but talking at KubeCon with someone from Kubernetes they mentioned they use this (see https://github.com/kubernetes/kubernetes/blob/master/hack/apidiff.sh and https://prow.k8s.io/view/gs/kubernetes-ci-logs/pr-logs/pull/129125/pull-kubernetes-apidiff-client-go/1887847435644964864 as a concrete example), and that the Go team has been responsive in adding features like support for generics. So I think it's less maintenance work if we leverage it (possibly wrapping it within checkapi)

[pellared]

I would also consider contributing to https://pkg.go.dev/golang.org/x/exp/cmd/gorelease. AFAIK the main issue is lack of support for multiple Go modules.

[atoulme]

OK, I will close this PR and maybe we can discuss this from the need perspective a bit more in the collector repository, and try any of the two tools you mention. The branch is still there if anyone wants to revisit.