feat(config): add OTLP trace export configuration support by mtoffl01 · Pull Request #4583 · DataDog/dd-trace-go

mtoffl01 · 2026-03-23T13:32:18Z

What does this PR do?

Adds configuration support for OTLP trace export mode. Actual OTLP trace export implementation will be done in a follow-up PR.

See: RFC

When OTEL_TRACES_EXPORTER=otlp is set, the tracer uses a separate OTLP collector endpoint and OTLP-specific headers instead of the standard Datadog agent trace endpoint.

Key changes:

Introduces otlpExportMode on internal/config.Config based on OTEL_TRACES_EXPORTER=otlp. When set, this toggles a new "otlp mode"
Introduces otlpTraceURL, and otlpHeaders fields on internal/config.Config, with getters/setters. otlpTraceURL is resolved from OTEL_EXPORTER_OTLP_TRACES_ENDPOINT (or defaults to agentHost:4318/v1/traces) and is fully independent of agentURL.
Refactors newHTTPTransport to accept fully resolved traceURL, statsURL, and headers, making it agnostic to Datadog vs OTLP mode.

Motivation

This is the configuration groundwork for supporting OTLP trace export. By centralizing URL/header resolution in internal/config and making the transport layer protocol-agnostic, the actual OTLP serialization (converting Datadog spans to the OTLP wire format) can be added in a follow-up PR with minimal additional plumbing.

Reviewer's Checklist

Changed code has unit tests for its functionality at or near 100% coverage.
System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
There is a benchmark for any new code, or changes to existing code.
If this interacts with the agent in a new way, a system test has been added.
New code is free of linting errors. You can check this by running make lint locally.
New code doesn't break existing tests. You can check this by running make test locally.
Add an appropriate team label so this PR gets put in the right place for the release notes.
All generated files are up to date. You can check this by running make generate locally.
Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild. Make sure all nested modules are up to date by running make fix-modules locally.

Unsure? Have a question? Request a review!

…port

codecov · 2026-03-23T13:35:54Z

Codecov Report

❌ Patch coverage is 85.88235% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.65%. Comparing base (5d005fa) to head (f0c6f00).

Files with missing lines	Patch %	Lines
internal/config/provider/provider.go	44.44%	5 Missing ⚠️
internal/config/config_helpers.go	84.21%	1 Missing and 2 partials ⚠️
ddtrace/tracer/transport.go	83.33%	2 Missing ⚠️
internal/config/provider/otelenvconfigsource.go	66.66%	2 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
ddtrace/tracer/option.go	`84.13% <100.00%> (ø)`
ddtrace/tracer/tracer.go	`88.35% <100.00%> (ø)`
internal/config/config.go	`60.88% <100.00%> (+60.88%)`	⬆️
ddtrace/tracer/transport.go	`87.62% <83.33%> (ø)`
internal/config/provider/otelenvconfigsource.go	`88.31% <66.66%> (ø)`
internal/config/config_helpers.go	`51.35% <84.21%> (ø)`
internal/config/provider/provider.go	`71.11% <44.44%> (ø)`

... and 430 files with indirect coverage changes

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datadog-datadog-prod-us1-2 · 2026-03-23T13:36:05Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 84.93%
• Overall Coverage: 60.03% (+4.03%)

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

🔗 Commit SHA: f0c6f00 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

pr-commenter · 2026-03-23T13:57:54Z

Benchmarks

Benchmark execution time: 2026-03-25 17:10:52

Comparing candidate commit f0c6f00 in PR branch mtoff/otlp-export-config with baseline commit 5d005fa in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 216 metrics, 8 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 ----------------------------------'

… to determine otlp mode

Made-with: Cursor

…traceURL

kakkoyun

LGTM

…nfig registry to reflect this

genesor

LGTM, few questions

genesor · 2026-03-25T15:36:18Z

+	if c.internalConfig.TraceProtocol() == traceProtocolV1 && !af.v1ProtocolAvailable {
 		c.internalConfig.SetTraceProtocol(traceProtocolV04, internalconfig.OriginCalculated)
-	}
-	if c.internalConfig.TraceProtocol() == traceProtocolV1 {
 		if t, ok := c.transport.(*httpTransport); ok {
-			t.traceURL = fmt.Sprintf("%s%s", agentURL.String(), tracesAPIPathV1)
+			t.traceURL = agentURL.String() + tracesAPIPath


Just wondering, should this be able to mutate the URL when we are in OTLP mode ?

Technically, it shouldnt.

DD_TRACE_AGENT_PROTOCOL_VERSION takes precedence over "otlp mode" config. And we are only in this "if" block if the user has explicitly configured DD_TRACE_AGENT_PROTOCOL_VERSION="1.0"

Co-authored-by: Benjamin De Bernardi <[email protected]>

Allow Config to resolve traceURL; pass this as a field into httptrans…

8f7f60f

…port

mtoffl01 added 8 commits March 23, 2026 10:24

Fix otlp protocol resolution and add tests for all new logic

3e3fec8

Implement OTEL_EXPORTER_OTLP_TRACES_HEADERS

c559f8f

Fix superfluous referecne to unsupport OTLP header config

cb6908e

Introduce otlpExportMode on Config; use this instead of traceProtocol…

a85fedf

… to determine otlp mode

fix relationship between otlpexportmode and protocol

33a9a37

replace tracer.config.otlpExportMode with internalconfig otlpExportMode

3e51fdd

Made-with: Cursor

Clean up resolveOTLPHeaders

5e252be

cleanup

51f72a2

mtoffl01 changed the title ~~(2) feat(tracer): Support otlp export~~ feat(tracer, config): Support all OTLP export configurations Mar 23, 2026

more cleanup and remove OTEL_EXPORTER_OTLP_ENDPOINT

b71eec7

mtoffl01 changed the title ~~feat(tracer, config): Support all OTLP export configurations~~ feat(config): add OTLP trace export configuration support Mar 23, 2026

mtoffl01 added 2 commits March 23, 2026 12:39

Store otlpTraceURL instead of traceURL on Config; let tracer resolve …

f48d44f

…traceURL

Make DD_TRACE_AGENT_PROTOCOL_VERSION override OTEL_TRACES_EXPORTER

f4360b4

mtoffl01 marked this pull request as ready for review March 23, 2026 18:46

mtoffl01 requested review from a team as code owners March 23, 2026 18:46

Merge branch 'main' into mtoff/otlp-export-config

49d0937

kakkoyun approved these changes Mar 24, 2026

View reviewed changes

mtoffl01 and others added 3 commits March 24, 2026 14:06

Use GetMap to resolve OTEL_EXPORTER_OTLP_TRACES_HEADERS and change co…

a88b7b2

…nfig registry to reflect this

give OTEL_EXPORTER_OTLP_TRACES_ENDPOINT default value of null

d475920

Merge branch 'main' into mtoff/otlp-export-config

8188bbe

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: waiting mergequeue-status: removed and removed mergequeue-status: waiting labels Mar 25, 2026

mtoffl01 force-pushed the mtoff/otlp-export-config branch from 9882338 to 8188bbe Compare March 25, 2026 15:21

merge conflicts

5072b2a

genesor approved these changes Mar 25, 2026

View reviewed changes

mtoffl01 and others added 2 commits March 25, 2026 11:38

Apply suggestion from @genesor

78e160f

Co-authored-by: Benjamin De Bernardi <[email protected]>

address PR review comments

f0c6f00

mtoffl01 enabled auto-merge (squash) March 25, 2026 16:43

mtoffl01 merged commit 944319d into main Mar 25, 2026
208 checks passed

mtoffl01 deleted the mtoff/otlp-export-config branch March 25, 2026 17:12

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feat(config): add OTLP trace export configuration support#4583

feat(config): add OTLP trace export configuration support#4583
mtoffl01 merged 19 commits into
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mtoff/otlp-export-config

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What does this PR do?

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