fix(otel): preserve Splunk Observability Cloud trace OTLP endpoint

[milan-berri]

Splunk ingest uses /v2/trace/otlp; _normalize_otel_endpoint must not append /v1/traces.

• Return trace endpoints unchanged when they match Splunk OTLP path patterns
• Add unit tests for observability.splunkcloud.com, signalfx.com, and /trace/otlp suffix
• Set OTEL_EXPORTER_OTLP_PROTOCOL in protocol selection tests (from_env precedence over OTEL_EXPORTER)

Relevant issues

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have Added testing in the tests/test_litellm/ directory, Adding at least 1 test is a hard requirement - see details
• My PR passes all unit tests on make test-unit
• My PR's scope is as isolated as possible, it only solves 1 specific problem
• I have requested a Greptile review by commenting @greptileai and received a Confidence Score of at least 4/5 before requesting a maintainer review

CI (LiteLLM team)

CI status guideline:

• 50-55 passing tests: main is stable with minor issues.
• 45-49 passing tests: acceptable but needs attention
• <= 40 passing tests: unstable; be careful with your merges and assess the risk.

• Branch creation CI run
  Link:

• CI run for the last commit
  Link:

• Merge / cherry-pick CI run
  Links:

Screenshots / Proof of Fix

Type

🐛 Bug Fix
✅ Test

Changes

Changes

• OTLP traces URL: Skip appending /v1/traces when the endpoint is Splunk-style …/v2/trace/otlp (fixes broken …/v2/trace/otlp/v1/traces URLs).
• Tests: Cover Splunk/SignalFx-style ingest URLs; collapse duplicate cases with parameterized.expand. Set OTEL_EXPORTER_OTLP_PROTOCOL in protocol-selection tests so from_env() stays deterministic.

[greptile-apps]

Greptile Summary

This PR fixes a bug in _normalize_otel_endpoint where Splunk Observability Cloud OTLP endpoints (/v2/trace/otlp) were incorrectly having /v1/traces appended, producing broken URLs. The fix adds an early-return guard for the Splunk path pattern, and restores test coverage of the OTEL_EXPORTER env-var fallback that the existing tests were inadvertently bypassing.

Confidence Score: 5/5

Safe to merge — targeted bug fix with no backwards-incompatible changes and full test coverage for the new code paths.

The guard is minimal and correctly scoped: it only fires for signal_type == 'traces' containing /v2/trace/otlp, leaving all other normalization paths unaffected. The prior concern about OTEL_EXPORTER fallback coverage is addressed by the two new dedicated tests. No P0/P1 findings remain.

No files require special attention.

Important Files Changed

Filename	Overview
litellm/integrations/opentelemetry.py	Four-line guard added to _normalize_otel_endpoint to skip rewriting when the endpoint contains /v2/trace/otlp; fix is correctly placed after the trailing-slash strip and before the standard path logic.
tests/test_litellm/integrations/test_opentelemetry.py	Adds parameterized tests for Splunk/SignalFx OTLP URLs; existing protocol tests updated to use OTEL_EXPORTER_OTLP_PROTOCOL for determinism; new fallback tests added to preserve OTEL_EXPORTER regression coverage.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["_normalize_otel_endpoint(endpoint, signal_type)"] --> B{signal_type valid?}
    B -- No --> C[Return endpoint unchanged]
    B -- Yes --> D[Strip trailing slash]
    D --> E{traces signal AND\ncontains /v2/trace/otlp?}
    E -- Yes --> F[Return endpoint unchanged\nSplunk OTLP path preserved]
    E -- No --> G{Already ends with\n/v1/signal_type?}
    G -- Yes --> H[Return endpoint]
    G -- No --> I{Ends with another\n/v1/signal path?}
    I -- Yes --> J[Replace signal segment and return]
    I -- No --> K[Append /v1/signal_type and return]

Loading

_{Reviews (3): Last reviewed commit: "test(otel): cover OTEL_EXPORTER fallback..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!