etcdctl: Migrate etcd-diagnosis as a new subcommand diagnosis

[seshachalam-yv]

Fixes #20275
Part of #20217

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

etcdctl sample output

✗ ./bin/etcdctl diagnosis --cluster -o diagnosis.json

cc @ahrtr

[k8s-ci-robot]

Hi @seshachalam-yv. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[seshachalam-yv]

Thanks @ahrtr for your review. I’ve addressed your comments.
Apologies for the delay — I was away for an extended period due to personal reasons.

[ahrtr]

Please license header for each new go file.

etcd/tests/e2e/reproduce_18667_test.go

Lines 1 to 13 in 636bbdd

	// Copyright 2025 The etcd Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

Also I suggest to move the directory diagnosis to etcdctl/ctlv3/command/diagnosis

[ahrtr]

pls signoff the commit or squash the commit (preferred)

[ahrtr]

LGTM with a minor comment.

Thank you!

[ahrtr]

For etcd version >= 3.6.0, we are able to get the quota by endpoint status query. For versions < 3.6.0, we still need to users to provide a value for this flag.

It's OK to enhance this in a followup PR.

[ahrtr]

/ok-to-test

[ahrtr]

Please resolve the workflow failures, thx

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: seshachalam-yv
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[k8s-ci-robot]

@seshachalam-yv: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-etcd-markdown-lint	95785f0	link	true	/test pull-etcd-markdown-lint
pull-etcd-e2e-386	95785f0	link	true	/test pull-etcd-e2e-386
pull-etcd-verify	95785f0	link	true	/test pull-etcd-verify
pull-etcd-unit-test-386	95785f0	link	true	/test pull-etcd-unit-test-386

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 360 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.40%. Comparing base (0de7907) to head (95785f0).
⚠️ Report is 111 commits behind head on main.

Files with missing lines	Patch %	Lines
...ctlv3/command/diagnosis/plugins/epstatus/plugin.go	0.00%	93 Missing ⚠️
.../ctlv3/command/diagnosis/plugins/metrics/plugin.go	0.00%	80 Missing ⚠️
...ctl/ctlv3/command/diagnosis/plugins/read/plugin.go	0.00%	68 Missing ⚠️
...lv3/command/diagnosis/plugins/membership/plugin.go	0.00%	54 Missing ⚠️
etcdctl/ctlv3/command/diagnosis_command.go	0.00%	47 Missing ⚠️
...l/ctlv3/command/diagnosis/plugins/common/client.go	0.00%	10 Missing ⚠️
...tcdctl/ctlv3/command/diagnosis/engine/diagnosis.go	0.00%	7 Missing ⚠️
etcdctl/ctlv3/ctl.go	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
etcdctl/ctlv3/ctl.go	0.00% <0.00%> (ø)
...tcdctl/ctlv3/command/diagnosis/engine/diagnosis.go	0.00% <0.00%> (ø)
...l/ctlv3/command/diagnosis/plugins/common/client.go	0.00% <0.00%> (ø)
etcdctl/ctlv3/command/diagnosis_command.go	0.00% <0.00%> (ø)
...lv3/command/diagnosis/plugins/membership/plugin.go	0.00% <0.00%> (ø)
...ctl/ctlv3/command/diagnosis/plugins/read/plugin.go	0.00% <0.00%> (ø)
.../ctlv3/command/diagnosis/plugins/metrics/plugin.go	0.00% <0.00%> (ø)
...ctlv3/command/diagnosis/plugins/epstatus/plugin.go	0.00% <0.00%> (ø)

... and 76 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #20280      +/-   ##
==========================================
+ Coverage   66.28%   69.40%   +3.11%     
==========================================
  Files         420      411       -9     
  Lines       34776    34587     -189     
==========================================
+ Hits        23053    24005     +952     
+ Misses      10321     9190    -1131     
+ Partials     1402     1392      -10     

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