include gorouter_time metrics report

[kart2bc]

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Summary

Backward Compatibility

Breaking Change? No

[linux-foundation-easycla]

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[ameowlia]

I think there are at least two options forward:

1. Move the call to CaptureGorouter to the accesslog handler. And move the calculation to gorouter time to access log handler.
2. OR set "FinishedAt" in the reporter handler, calculate gorouter_time in the reporter handler, send a metric for gorouter_time in the reporter handler, set gorouter_time on the reqInfo in the reporter handler, and then use that calculated value for gorouter time in the access log handler.

Also needed

• tests
• this needs to be behind the config flag for per request metrics

[kart2bc]

I think there are at least two options forward:

1. Move the call to CaptureGorouter to the accesslog handler. And move the calculation to gorouter time to access log handler.
2. OR set "FinishedAt" in the reporter handler, calculate gorouter_time in the reporter handler, send a metric for gorouter_time in the reporter handler, set gorouter_time on the reqInfo in the reporter handler, and then use that calculated value for gorouter time in the access log handler.

Also needed

• tests
• this needs to be behind the config flag for per request metrics

I prefer the option #2.
Plan to move the calculation to an utility. However, the accesslogger been called before reporthandler.
Is my understanding correct?

nvm. Figured out the stack been called in reverse order while processing the response. So finished at will be called once all the request been processed.

[ameowlia]

I think you might also need to add a promethius metric implementation: https://github.com/cloudfoundry/gorouter/blob/main/metrics_prometheus/metrics.go

[kart2bc]

• Test results *

{"status":"success","data":{"resultType":"vector","result":[{"metric":{"__v1_type":"ValueMetric","deployment":"cf-217600a306e78084eaf0","index":"e33e6db0-2af5-4b4a-adf7-8b18bb1ff447","ip":"10.10.0.12","job":"router","origin":"gorouter","product":"Small Footprint Tanzu Platform for Cloud Foundry","source_id":"gorouter","system_domain":"sys.tas.z547a4313.shepherd.lease"},"value":[1744150830.000,"0.26723100000000666"]}]}}```

[geofffranks]

I'm confused how the access log record tests still pass with no updates. After removing gorouterTime(), and having it log the pre-calculated GorouterTime value, the GorouterTime would be 0, unless the test was modified to set GorouterTime on the fake access log record used in the tests.

... right? 😕

[kart2bc]

Figured this issue after running the whole suite. Addressed them here #473.

[geofffranks]

Can you replace this with a check to make sure we get a nonzero value on GorouterTime in the access log record?

[kart2bc]

Addressed it here. #473

[kart2bc]

Closing this PR due to CLA issue. Opened a new one. #473