feat: clear_metrics

[wlx5575]

Description

Related Issue(s)

• Fixes: Question: Request for API to Clear Gateway Monitoring Data on Port 15001 #16526

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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• 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

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[codecov]

Codecov Report

Attention: Patch coverage is 3.57143% with 27 lines in your changes missing coverage. Please review.

Project coverage is 68.77%. Comparing base (27f2d73) to head (d5459a7).
Report is 98 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtgate/vtgate.go	0.00%	22 Missing ⚠️
go/vt/vtgate/scatter_conn.go	16.66%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16550      +/-   ##
==========================================
+ Coverage   68.75%   68.77%   +0.01%     
==========================================
  Files        1556     1556              
  Lines      199806   199831      +25     
==========================================
+ Hits       137384   137431      +47     
+ Misses      62422    62400      -22     

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[mattlord]

Thank you, @wlx5575 ! As noted, we'll need to use a different API.

Thanks!

[mattlord]

We'll have to do it differently as this package is not and should not be tied to vtgate in any direct way as it's used by all commands/binaries which publish metrics:

❯ git grep go/stats/prometheusbackend | cat
go/cmd/mysqlctl/command/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/mysqlctld/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/vtbackup/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/vtctld/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/vtgate/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/vtorc/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"
go/cmd/vttablet/cli/plugin_prometheusbackend.go:	"vitess.io/vitess/go/stats/prometheusbackend"

[wlx5575]

Thank you for your feedback!could you please suggest where it would be more appropriate to place this API? I can make adjustments based on your suggestion.

[mattlord]

If you want this to be for vtgate then add it to vtgate. If you want it to be generic then the stats package has a global dynamic registry of stats that could be reset (and either way, this has nothing specifically to do with the prometheus backend).

[mattlord]

VTGate:

vitess/go/vt/vtgate/vtgate.go

Lines 378 to 379 in cf8f5d1

	vtgateInst.registerDebugHealthHandler()
	vtgateInst.registerDebugEnvHandler()

[mattlord]

No need for the ELSE and we can remove the whitespace. If statsName is empty we return. So we can simply return after that IF block as well.

[wlx5575]

#16550 (review)

Thank you, @wlx5575 ! As noted, we'll need to use a different API.

Could you also please create a quick issue that lays out the use case for this that you had noted in Slack?

Thanks!

[mattlord]

This will be a problem because 1) this does not include the full list of vtgate stats today 2) when new ones are added in the future it will not be clear (or expected) to have to find this and add the new stat here for the reset.

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This PR was closed because it has been stale for 7 days with no activity.