in_opentelemetry: return not found for invalid endpoint

[edsiper]

Summary

Fixes #12032.

• Return HTTP 404 for unknown OpenTelemetry input endpoints instead of HTTP 400.
• Add the missing Not Found response message mapping for the new HTTP server response helper.
• Add focused integration coverage for an invalid OTLP HTTP/2 endpoint.

Root Cause

The OpenTelemetry input request dispatch treated endpoint mismatches as bad requests before method, payload, or content-type validation. That made an unknown OTLP path return 400 error: invalid endpoint instead of the expected 404.

Validation

• tests/integration/.venv/bin/python -m pytest tests/integration/scenarios/in_opentelemetry/tests/test_in_opentelemetry_001.py::test_in_opentelemetry_http2_invalid_endpoint_returns_404 -q
• VALGRIND=1 VALGRIND_STRICT=1 tests/integration/.venv/bin/python -m pytest tests/integration/scenarios/in_opentelemetry/tests/test_in_opentelemetry_001.py::test_in_opentelemetry_http2_invalid_endpoint_returns_404 -q
• ctest --test-dir build -R flb-it-opentelemetry --output-on-failure
• tests/integration/.venv/bin/python .github/scripts/commit_prefix_check.py
• GITHUB_EVENT_NAME=pull_request GITHUB_BASE_REF=master tests/integration/.venv/bin/python .github/scripts/commit_prefix_check.py

Summary by CodeRabbit

• Bug Fixes

  • Invalid OpenTelemetry HTTP/2 endpoints now return a proper 404 Not Found response instead of 400 Bad Request.
  • Response text now matches the 404 status more accurately.

• Tests

  • Added integration coverage for invalid HTTP/2 OpenTelemetry requests.
  • Verified that bad endpoint requests do not create logs, metrics, or traces.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: df7f089f-2850-4cbe-b392-9bf39b7d4eb7

📥 Commits

Reviewing files that changed from the base of the PR and between 46e15a1 and a560b02.

📒 Files selected for processing (2)

• plugins/in_opentelemetry/opentelemetry_prot.c
• tests/integration/scenarios/in_opentelemetry/tests/test_in_opentelemetry_001.py

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📝 Walkthrough

Walkthrough

The OpenTelemetry input plugin's HTTP handler now returns HTTP 404 with a "Not Found" message for invalid endpoint requests, replacing the previous HTTP 400 response. An integration test was added to verify the new 404 behavior over HTTP/2 and confirm no data is stored.

Changes

Invalid Endpoint 404 Response

Layer / File(s)	Summary
404 status and message handling plugins/in_opentelemetry/opentelemetry_prot.c	send_response_ng() sets response message to "Not Found" for 404 status; invalid endpoint fallback in opentelemetry_prot_handle_ng() changed from HTTP 400 to 404.
Integration test coverage tests/integration/scenarios/in_opentelemetry/tests/test_in_opentelemetry_001.py	Adds test sending an HTTP/2 request to an invalid endpoint, asserting a 404 response and verifying no logs, metrics, or traces are stored.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant OTelInput as OpenTelemetry Input Plugin
    participant Storage as data_storage

    Client->>OTelInput: HTTP/2 request to invalid endpoint
    OTelInput->>OTelInput: opentelemetry_prot_handle_ng() detects invalid endpoint
    OTelInput->>OTelInput: send_response_ng() sets 404 "Not Found"
    OTelInput-->>Client: HTTP 404 "error: invalid endpoint"
    Note over Storage: No logs, metrics, or traces written

Loading

Related issues: #12032 - OpenTelemetry input return 400 on invalid endpoint instead of 404

Suggested labels: bug, opentelemetry, tests

Suggested reviewers: none identified

🐰 A hopeful request to a path unknown,
Once got a 400, now stands alone —
"Not Found," it says, with proper cheer,
404 arrives, the fix is here!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: invalid OpenTelemetry endpoints now return Not Found/404.
Linked Issues check	✅ Passed	The PR implements the requested 404 behavior for invalid OTLP endpoints and adds coverage for it.
Out of Scope Changes check	✅ Passed	The response mapping and integration test are directly related to the linked invalid-endpoint fix.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch otlp-invalid-endpoint-12032

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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