Support passing filters to discovery.NewHealthCheck(...)

[timvaillancourt]

Description

This PR resolves #16074 by allowing filters to be passed into discovery.NewHealthCheck(...) (vs. being inherited from flags only) as vtgate and txthrottler (in vttablet) have very different expectations of filtering healthchecks

This change makes "filtering" a 1st-class feature of the healthcheck logic and both use-cases can pass in their required filter(s). This ability to pass filters will be used to filter the healthcheck streams for the txthrottler to the local-shard only, in order to resolve #16074

Related Issue(s)

• Fixes: Bug Report: txthrottler watches health streams for every keyspace/shard #16074, where txthrottler monitors an entire cell instead of the single-shard it should concern itself with

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 69.76744% with 13 lines in your changes missing coverage. Please review.

Project coverage is 69.45%. Comparing base (eb29999) to head (19216d2).
Report is 207 commits behind head on main.

Files with missing lines	Patch %	Lines
.../vttablet/tabletserver/txthrottler/tx_throttler.go	57.14%	12 Missing ⚠️
go/vt/throttler/demo/throttler_demo.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16170      +/-   ##
==========================================
+ Coverage   68.69%   69.45%   +0.75%     
==========================================
  Files        1547     1571      +24     
  Lines      198297   202996    +4699     
==========================================
+ Hits       136228   140981    +4753     
+ Misses      62069    62015      -54     

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[mattlord]

You can address the failing test by merging in main now:

git fetch --all
git merge origin/main

🙏

[timvaillancourt]

Correction: this isn't necessarily a regression unless you're jumping from older releases. I submitted a fix for this earlier but it was not merged due to other refactoring I thought would have the same result 🤦

Our v14 release doesn't hit this due to using discovery.LegacyHealthCheck (now gone)

[harshit-gangal]

changes looks good. we should test the new changes.

[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.

[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.

[timvaillancourt]

@mattlord / @harshit-gangal I've added a basic test for tablet filtering to TestCellTabletsWatcher. Also each tablet filter implementation is tested in a new test from this PR: TestNewVTGateHealthCheckFilters

Let me know if we'd like to test anything further 🙇!

[mattlord]

Thanks, @timvaillancourt !

[timvaillancourt]

@mattlord thanks for the review!

You mentioned documentation for the various filtering earlier. The command line flags are documented of course, but it seems the concept of filtering in general is not explained in the overall docs

Let me know if you were thinking about an actual doc section and if you had a suggestion where it should be added 🙇

[deepthi]

@timvaillancourt every one of the commits in this PR is missing a sign-off. You will need to amend the commits and force-push. Once that is done, you should be able to push the button to merge. Please do "Squash and merge", that's our convention.