grpc-proxy: add option to allow non empty CN

[Sh4d1]

In some cases, grpc-proxy can be used with CN based auth.

Fixes #11970

Signed-off-by: Patrik Cyvoct patrik@ptrk.io

[codecov-commenter]

Codecov Report

Merging #11974 into master will increase coverage by 1.04%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master   #11974      +/-   ##
==========================================
+ Coverage   66.34%   67.38%   +1.04%     
==========================================
  Files         403      403              
  Lines       37245    39044    +1799     
==========================================
+ Hits        24709    26309    +1600     
- Misses      11017    11113      +96     
- Partials     1519     1622     +103     

Impacted Files	Coverage Δ
etcdmain/grpc_proxy.go	16.11% <50.00%> (+0.25%)	⬆️
client/keys.go	69.34% <0.00%> (-22.12%)	⬇️
clientv3/naming/grpc.go	63.15% <0.00%> (-12.29%)	⬇️
etcdmain/gateway.go	24.13% <0.00%> (-9.74%)	⬇️
auth/simple_token.go	81.51% <0.00%> (-7.57%)	⬇️
clientv3/leasing/util.go	91.66% <0.00%> (-6.67%)	⬇️
client/client.go	70.58% <0.00%> (-2.95%)	⬇️
etcdserver/storage.go	57.77% <0.00%> (-1.20%)	⬇️
etcdserver/cluster_util.go	64.88% <0.00%> (-0.89%)	⬇️
etcdserver/api/v2store/store.go	88.57% <0.00%> (-0.01%)	⬇️
... and 33 more

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[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.

[Sh4d1]

@tangcong maybe?

[ptabor]

Suggested how to fix that problem in: #11970 (comment)
I think we shouldn't introduce new public flags and handle it internally.

[tangcong]

I will take a closer look later, this issue(Jun 4) does not seem to be caused by pr 12114 that is submitted in July. I agree with your idea, currently healthcheck is not optimal. @ptabor

[ptabor]

The fix in #12273 has been merged. I assume the problem is solved and we can close this PR now, as stated in #11970 (comment). Thank you.

[Sh4d1]

True my bad 😄