pkg/featuregate: Return MutableFeatureGate interface in New function

[ivanvc]

Avoid returning an unexported struct in the exported New function. Instead, return the MutableFeatureGate interface.

I found this issue in the recently introduced featuregate package while reviewing the staleness of #18370. Since this package was introduced in v3.6, it makes sense to merge and backport to release-3.6.

/cc @ahrtr @siyuanfoundation

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.95%. Comparing base (4fec4ca) to head (491199f).
Report is 14 commits behind head on main.

Additional details and impacted files

Files with missing lines	Coverage Δ
pkg/featuregate/feature_gate.go	88.96% <100.00%> (ø)

... and 59 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #19803      +/-   ##
==========================================
- Coverage   68.86%   65.95%   -2.91%     
==========================================
  Files         421      421              
  Lines       35863    35863              
==========================================
- Hits        24696    23654    -1042     
- Misses       9746    10770    +1024     
- Partials     1421     1439      +18     

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[ivanvc]

CodeCov failure comes from the Prow job failure: https://prow.k8s.io/view/gs/kubernetes-ci-logs/logs/post-etcd-coverage-report/1915918905981800448. I tried re-running the job, but I don't have permission to do that.

[ahrtr]

Thanks @ivanvc for the catch.

Not sure why the coverage workflow fails from time to time.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahrtr, ivanvc, siyuanfoundation

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[ahrtr]

/cherry-pick release-3.6

[k8s-infra-cherrypick-robot]

@ahrtr: new pull request created: #19816

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In response to this:

/cherry-pick release-3.6

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[ivanvc]

Thanks @ivanvc for the catch.

Not sure why the coverage workflow fails from time to time.

It looks like these three tests are flaky according to testgrid:

• go.etcd.io/etcd/tests/v3/integration/clientv3.TestMaintenanceSnapshotErrorInflight
• go.etcd.io/etcd/server/v3/etcdserver/api/v3compactor.TestPeriodicHourly
• go.etcd.io/etcd/server/v3/etcdserver/api/v3compactor.TestPeriodicMinutes

[ahrtr]

• go.etcd.io/etcd/server/v3/etcdserver/api/v3compactor.TestPeriodicHourly
• go.etcd.io/etcd/server/v3/etcdserver/api/v3compactor.TestPeriodicMinutes

PTAL #19748

[ivanvc]

@ahrtr, PTAL 👉 kubernetes/test-infra#34381 (comment)