refactor(config): migrate spanAttributeSchemaVersion by funyjane · Pull Request #4711 · DataDog/dd-trace-go

funyjane · 2026-05-01T13:46:42Z

Summary

Adds a public Config.SpanAttributeSchemaVersion() getter on internal/config.Config. The field itself was already declared and initialised by loadConfig; this just exposes a public accessor.
Removes the duplicate spanAttributeSchemaVersion field from the legacy tracer config struct and the c.spanAttributeSchemaVersion = int(namingschema.GetVersion()) assignment in newConfig.
Rewires the two readers (telemetry.go startup config and tracer.go StartSpan hot path) to read through the new getter.
Getter avoids defer because it is read once per local-root span — matches the hot-path pattern from the peer-service migration (refactor(config): peer service revamp #4653) and the README guidance.
namingschema.LoadFromEnv() is preserved: contrib packages still consume the namingschema global via GetVersion().

Jira: APMAPI-1887
EPIC: APMAPI-1881 — Go Config Revamp: Migrate tracer

Test plan

go build ./...
go vet ./ddtrace/tracer/... ./internal/config/...
go test ./internal/config/...
go test ./ddtrace/tracer/... (full suite)
Existing attribute_schema_is_set_v0/v1/wrong_value (tracer_test.go) and defaults-with-schema-v1 (option_test.go) pass without modification.

Move the spanAttributeSchemaVersion field from the legacy tracer config struct to internal/config.Config. The field is already declared and initialised by loadConfig; this change exposes a public getter and rewires the two readers (startTelemetry and the StartSpan hot path) to use it. The getter avoids defer since it is read once per local-root span, matching the README's hot-path guidance. namingschema.LoadFromEnv() is preserved because contrib packages still consume the namingschema global via GetVersion(). Refs: APMAPI-1887 (EPIC APMAPI-1881)

codecov · 2026-05-01T13:51:31Z

Codecov Report

❌ Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.02%. Comparing base (625c602) to head (89c5a54).

Files with missing lines	Patch %	Lines
internal/config/config.go	0.00%	5 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
ddtrace/tracer/option.go	`85.05% <ø> (ø)`
ddtrace/tracer/telemetry.go	`88.88% <ø> (ø)`
ddtrace/tracer/tracer.go	`88.42% <100.00%> (ø)`
internal/config/config.go	`60.18% <0.00%> (+60.18%)`	⬆️

... and 444 files with indirect coverage changes

🚀 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.

datadog-datadog-prod-us1 · 2026-05-01T13:52:32Z

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 20.00%
• Overall Coverage: 61.38% (+3.87%)

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 89c5a54 | Docs | Datadog PR Page | Give us feedback!}

pr-commenter · 2026-05-01T15:26:11Z

Benchmarks

Benchmark execution time: 2026-05-04 11:50:14

Comparing candidate commit 89c5a54 in PR branch config-revamp/span-attribute-schema-version with baseline commit 625c602 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 209 metrics, 9 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

mtoffl01

one nit, otherwise LGTM!

mtoffl01 · 2026-05-01T17:27:54Z

 		{Name: "debug_stack_enabled", Value: c.internalConfig.DebugStack()},
 		{Name: "profiling_hotspots_enabled", Value: c.internalConfig.ProfilerHotspotsEnabled()},
-		{Name: "trace_span_attribute_schema", Value: c.spanAttributeSchemaVersion},
+		{Name: "trace_span_attribute_schema", Value: c.internalConfig.SpanAttributeSchemaVersion()},


let's delete this entirely; SpanAttributeSchemaVersion is now automatically reported to telemetry at startup via the config provider's telemetry implementation.

If existing tests fail as a result , you can probably just modify their expectations

thx, fixed it.

…y entry The config provider auto-reports DD_TRACE_SPAN_ATTRIBUTE_SCHEMA via its telemetry implementation when loadConfig calls p.GetString, so the legacy explicit entry in startTelemetry is duplicate. Update the test expectation to match the auto-reported default ("") instead of the legacy int (0).

darccio · 2026-05-04T10:41:47Z

 }

+// SpanAttributeSchemaVersion returns the configured DD_TRACE_SPAN_ATTRIBUTE_SCHEMA version.
+// Read on the span-creation hot path; avoids defer to minimise lock cost.


funyjane · 2026-05-04T11:11:12Z

/merge

gh-worker-devflow-routing-ef8351 · 2026-05-04T11:11:16Z

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2026-05-04 11:11:16 UTC ℹ️ Start processing command /merge

2026-05-04 11:11:22 UTC ℹ️ MergeQueue: waiting for PR to be ready

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2026-05-04 11:52:13 UTC ℹ️ MergeQueue: merge request added to the queue

The expected merge time in main is approximately 16m (p90).

2026-05-04 12:06:58 UTC ℹ️ MergeQueue: This merge request was merged

### What does this PR do? - Adds a public `Config.MaxTagsHeaderLen()` getter on `internal/config.Config`. - Initializes the field in `loadConfig` from `DD_TRACE_X_DATADOG_TAGS_MAX_LENGTH`, preserving the existing clamping semantics (negative → 0; > `MaxPropagatedTagsLength` → clamped down to that value). - Adds `DefaultMaxTagsHeaderLen` and `MaxPropagatedTagsLength` exported constants in `internal/config`. - Removes the duplicate env resolution from `tracer/option.go` and the `defaultMaxTagsHeaderLen` / `maxPropagatedTagsLength` constants there. - The propagator is now constructed using `c.internalConfig.MaxTagsHeaderLen()` instead of locally re-reading the env var. ### Motivation Continued config-migration work: move env resolution of `DD_TRACE_X_DATADOG_TAGS_MAX_LENGTH` into `internal/config` to match the pattern established by recent migrations (e.g. #4711, #4653). --------- Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

funyjane requested review from a team as code owners May 1, 2026 13:46

mtoffl01 approved these changes May 1, 2026

View reviewed changes

funyjane added 2 commits May 1, 2026 20:30

test(tracer): use lowercase telemetry key for consistency

17d37a9

darccio approved these changes May 4, 2026

View reviewed changes

Merge branch 'main' into config-revamp/span-attribute-schema-version

89c5a54

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: waiting mergequeue-status: queued mergequeue-status: in_progress and removed mergequeue-status: waiting mergequeue-status: queued labels May 4, 2026

gh-worker-dd-mergequeue-cf854d Bot merged commit ac16240 into main May 4, 2026
222 checks passed

gh-worker-dd-devflow-36fce6 Bot removed the mergequeue-status: in_progress label May 4, 2026

gh-worker-dd-mergequeue-cf854d Bot deleted the config-revamp/span-attribute-schema-version branch May 4, 2026 12:06

gh-worker-dd-devflow-36fce6 Bot added the mergequeue-status: done label May 4, 2026

mtoffl01 mentioned this pull request May 5, 2026

refactor(config): migrate maxTagsHeaderLen #4730

Merged

funyjane mentioned this pull request May 8, 2026

refactor(config): migrate dogstatsdAddr #4741

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refactor(config): migrate spanAttributeSchemaVersion#4711

refactor(config): migrate spanAttributeSchemaVersion#4711
gh-worker-dd-mergequeue-cf854d[bot] merged 4 commits into
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