Remove support for expvar metrics

[joeyyy09]

Which problem is this PR solving?

• Resolves [deprecation] Remove support for expvar metrics #4722

Description of the changes

• This PR removes deprecated expvar CLI flags and the related backend from the codebase.

How was this change tested?

• Tested locally by running the application without the deprecated flags to ensure that it functions correctly.

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• [] I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[yurishkuro]

I would start with deleting internal/metrics/expvar and then making sure make build-binaries-(your platform) is ok.

[joeyyy09]

I would start with deleting internal/metrics/expvar and then making sure make build-binaries-(your platform) is ok.

Yeah, i removed them and made sure the build is okay.

[joeyyy09]

@yurishkuro can you review these changes and let me know if i've got to change any more?

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 95.27%. Comparing base (5ddcaa9) to head (1715c01).
Report is 1 commits behind head on main.

Files	Patch %	Lines
internal/metrics/metricsbuilder/builder.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5437      +/-   ##
==========================================
- Coverage   95.29%   95.27%   -0.03%     
==========================================
  Files         334      331       -3     
  Lines       16233    16113     -120     
==========================================
- Hits        15469    15351     -118     
+ Misses        583      582       -1     
+ Partials      181      180       -1     

Flag	Coverage Δ
badger_v1	7.97% <ø> (ø)
badger_v2	1.88% <ø> (ø)
cassandra-3.x-v1	16.27% <ø> (ø)
cassandra-3.x-v2	1.81% <ø> (ø)
cassandra-4.x-v1	16.27% <ø> (ø)
cassandra-4.x-v2	1.81% <ø> (ø)
elasticsearch-5.x	1.73% <ø> (ø)
elasticsearch-6.x	1.73% <ø> (+0.01%)	⬆️
elasticsearch-7.x	1.72% <ø> (-0.02%)	⬇️
elasticsearch-8.x	1.72% <ø> (-0.02%)	⬇️
grpc_v1	10.13% <ø> (ø)
grpc_v2	7.36% <ø> (+0.01%)	⬆️
kafka	9.68% <ø> (ø)
opensearch-1.x	1.73% <ø> (+0.01%)	⬆️
opensearch-2.x	1.72% <ø> (ø)
unittests	93.46% <50.00%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

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[yurishkuro]

please make sure make lint test are green

[joeyyy09]

please make sure make lint test are green

Yeah, fixed them. Thanks for the help! Is there anything i need to change?

[yurishkuro]

You need to query Prometheus endpoint on each binary before and after changes to make sure no changes to metrics names happen.

[joeyyy09]

You need to query Prometheus endpoint on each binary before and after changes to make sure no changes to metrics names happen.

Yeah, I'll verify this once.

[joeyyy09]

@yurishkuro I've resolved all the edits, thank you for helping me out. Absolutely sorry for messing up the namespaces. Can you please let me know if there's anything more i need to do? I'm willing to make the entire changes till this issue gets resolved.

[yurishkuro]

I still see breaking changes. You need to test that the metrics names are the same, by running each of the main Jaeger components from your branch and from main (e.g. SPAN_STORAGE_TYPE=grpc-plugin go run ./cmd/query) and comparing the output of curl http://localhost:16687/metrics (admin port will be different for different binaries, see logs)

[joeyyy09]

I still see breaking changes. You need to test that the metrics names are the same, by running each of the main Jaeger components from your branch and from main (e.g. SPAN_STORAGE_TYPE=grpc-plugin go run ./cmd/query) and comparing the output of curl http://localhost:16687/metrics (admin port will be different for different binaries, see logs)

Okay, will work on it!