trace: add OpenTelemetry backend, deprecate OpenTracing

[timvaillancourt]

Description

To address #17341 and #19621, this PR adds a new --tracer opentelemetry backend that exports traces via OTLP/gRPC. The existing opentracing-jaeger and opentracing-datadog backends are deprecated and will be removed in v25.

Basically, the world is consolidating on OpenTelemetry. This is great for Vitess, because we can eventually (v25+) run a single tracing implementation.

The motivation here is that jaeger-client-go has been archived for a while now and the Jaeger project recommends migrating to OpenTelemetry. Since our Datadog plugin uses the OpenTracing bridge in dd-trace-go, it makes sense to deprecate both at once

Both old backends continue to work in v24, they just log a deprecation warning at startup. This gives users a release cycle to migrate

What changed

• New otel.go implements the tracingService interface using the OTel SDK
• New plugin_otel.go registers the "opentelemetry" factory with an OTLP/gRPC exporter
• Custom gRPC interceptors for trace context propagation (the otelgrpc library removed its interceptor API in v0.63.0, so we write thin wrappers that fit the existing tracingService interface)
• The shared --tracing-sampling-rate flag moved from plugin_jaeger.go to trace.go so all backends can reference it without duplicate flag registration
• plugin_jaeger.go and plugin_datadog.go log a deprecation warning
• Changelog entry for v24 covering the new backend, deprecation, and migration path

New flags

• --otel-endpoint (default localhost:4317) - collector endpoint (gRPC)
• --otel-insecure (default false) - use insecure connection to collector

v25 cleanup

After the deprecation period we can delete opentracing.go, plugin_jaeger.go, plugin_datadog.go, logger.go and drop opentracing-go, opentracing-contrib/go-grpc, uber/jaeger-client-go, and dd-trace-go.v1 from go.mod. vtadmin/grpcserver/server.go also has direct OpenTracing usage that will need migrating

Related Issue(s)

Resolves: #17341 and #19621

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

Deployment Notes

No impact for existing deployments. The new opentelemetry backend is opt-in. Existing opentracing-jaeger and opentracing-datadog users will see a deprecation warning in their logs but nothing else changes

AI Disclosure

Written primarily by Claude Code - I provided direction on the design (coexistence vs replacement, flag naming, deprecation strategy)

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

❌ Patch coverage is 27.02703% with 162 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.68%. Comparing base (70c7a72) to head (be706b1).
⚠️ Report is 124 commits behind head on main.

Files with missing lines	Patch %	Lines
go/trace/otel.go	31.44%	109 Missing ⚠️
go/trace/plugin_otel.go	12.06%	51 Missing ⚠️
go/trace/trace.go	0.00%	2 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (70c7a72) and HEAD (be706b1). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (70c7a72)	HEAD (be706b1)
	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #19619       +/-   ##
===========================================
- Coverage   69.67%   43.68%   -25.99%     
===========================================
  Files        1614        9     -1605     
  Lines      216793      396   -216397     
===========================================
- Hits       151044      173   -150871     
+ Misses      65749      223    -65526     

Flag	Coverage Δ
partial	43.68% <27.02%> (?)

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[promptless]

📝 Documentation updates detected!

New suggestion: Document OpenTelemetry tracing backend and deprecate OpenTracing

---

Tip: Tag @Promptless in GitHub PR comments to guide documentation changes during code review 🐙

[Copilot]

Pull request overview

Adds an OpenTelemetry tracing backend to go/trace (OTLP/gRPC exporter) and begins deprecating the existing OpenTracing-based backends, aligning Vitess tracing with current ecosystem standards.

Changes:

• Introduces a new --tracer opentelemetry backend using the OTel SDK + OTLP/gRPC exporter and custom gRPC interceptors for context propagation.
• Moves --tracing-sampling-rate registration to trace.go so all tracing backends share it, and adds OTel-specific flags (--otel-endpoint, --otel-insecure).
• Deprecates opentracing-jaeger and opentracing-datadog with startup warnings and documents the migration path in the v24 changelog.

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
go/trace/trace.go	Centralizes shared tracing flags (incl. sampling rate) for all backends.
go/trace/plugin_otel.go	Registers the new opentelemetry backend and exposes OTel exporter flags.
go/trace/otel.go	Implements tracingService for OTel and provides custom gRPC interceptors + context parsing helpers.
go/trace/otel_test.go	Adds unit tests for OTel carrier decoding, span plumbing, and attribute conversion.
go/trace/plugin_jaeger.go	Removes duplicate sampling-rate flag registration and adds deprecation warning/docs for Jaeger backend.
go/trace/plugin_datadog.go	Adds deprecation warning/docs for Datadog OpenTracing backend.
go/flags/endtoend/vttablet.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go/flags/endtoend/vtgate.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go/flags/endtoend/vtctld.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go/flags/endtoend/vtctlclient.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go/flags/endtoend/vtcombo.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go/flags/endtoend/vtclient.txt	Updates generated flag output to include OTel flags and updated sampling-rate help.
go.mod	Adds OTLP trace exporter deps and bumps some related indirect deps.
go.sum	Records new module checksums for updated/added deps.
changelog/24.0/24.0.0/summary.md	Documents the new OTel backend, deprecations, and migration steps.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 15 out of 16 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 15 out of 16 changed files in this pull request and generated 6 comments.

[Copilot]

Pull request overview

Copilot reviewed 15 out of 16 changed files in this pull request and generated no new comments.

[timvaillancourt]

@mattlord ready for a re-review now. Thanks!

[mattlord]

LGTM! Nice work on this, @timvaillancourt ! ❤️

[nickvanw]

Leaving one correctness follow-up.

I verified this locally and left the details inline on the NewFromString path.