fix: langwatch traces all api endpoints

[HzaRashid]

skips open telemetry setup to prevent LangWatch from picking up all instrumented traffic (e.g., api calls #9567), and creates a dedicated TracerProvider so that it continues to trace flow execution.

Summary by CodeRabbit

• New Features
  • Enhanced LangWatch integration with improved tracing and observability capabilities through optimized OpenTelemetry support.
  • Implemented lazy-initialized tracer provider for efficient resource management and flexible observability configuration.

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Walkthrough

A single file modification to add lazy-initialized OpenTelemetry tracer provider support to LangWatchTracer, including class attribute addition, trace call enhancement, and setup method modification with OTL provider configuration.

Changes

Cohort / File(s)

Summary

LangWatch OpenTelemetry Tracer Provider src/backend/base/langflow/services/tracing/langwatch.py

Added tracer_provider class attribute to LangWatchTracer. Modified trace creation to pass tracer_provider=self.tracer_provider. Enhanced setup_langwatch with lazy-initialized shared OpenTelemetry tracer provider: imports OTLPSpanExporter, Resource, TracerProvider, BatchSpanProcessor; conditionally creates Resource and tracer provider from environment variables; attaches BatchSpanProcessor; initializes LangWatch client with skip_open_telemetry_setup=True.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• Review the lazy-initialization logic and thread-safety considerations for the shared tracer_provider attribute
• Verify correct handling of environment variables (LANGWATCH_API_KEY, LANGWATCH_ENDPOINT)
• Confirm OpenTelemetry configuration chain (Resource → OTLPSpanExporter → TracerProvider → BatchSpanProcessor)
• Ensure skip_open_telemetry_setup=True prevents duplicate initialization and doesn't cause conflicts with existing tracing setup

Pre-merge checks and finishing touches

Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 error, 4 warnings)

Check name	Status	Explanation	Resolution
Test Coverage For New Implementations	❌ Error	The PR introduces LangWatchTracer class with tracer_provider initialization and OTLP configuration, but no tests exist for the new LangWatchTracer implementation.	Add test_langwatch_tracer.py with tests for lazy initialization, OTLP configuration, skip_open_telemetry_setup parameter, shared provider behavior, and regression tests.
Title check	⚠️ Warning	The PR title 'fix: langwatch traces all api endpoints' is somewhat misleading. The actual change prevents LangWatch from tracing ALL API endpoints by skipping OpenTelemetry setup and using a dedicated TracerProvider to limit tracing to flow execution only.	Revise the title to accurately reflect the fix, such as: 'fix: prevent langwatch from tracing all api endpoints' or 'fix: limit langwatch tracing to flow execution only'
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.
Test Quality And Coverage	⚠️ Warning	No new tests added for LangWatchTracer class modifications including tracer_provider initialization, OpenTelemetry setup, lazy initialization, and LangWatch client integration.	Add comprehensive unit tests covering tracer provider initialization, OpenTelemetry component instantiation, lazy initialization behavior, parameter passing to LangWatch client, missing API key handling, and ImportError handling for langwatch module.
Test File Naming And Structure	⚠️ Warning	The PR modifies langwatch.py with new OpenTelemetry setup logic but lacks corresponding unit tests for tracer provider initialization, lazy-loading, and edge cases.	Add unit tests in test_langwatch_tracer.py covering tracer provider initialization, lazy-loading, environment variable handling, OpenTelemetry configuration, and error scenarios.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Excessive Mock Usage Warning	✅ Passed	The custom check for excessive mock usage applies only to test files. This PR modifies only production code and metadata files, with no test file changes.

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[github-actions]

Frontend Unit Test Coverage Report

Coverage Summary

Lines	Statements	Branches	Functions
	16.65% (4686/28138)	10.02% (2179/21743)	10.93% (676/6180)

Unit Test Results

Tests	Skipped	Failures	Errors	Time
1829	0 💤	0 ❌	0 🔥	24.571s ⏱️

[codecov]

Codecov Report

❌ Patch coverage is 0% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 33.09%. Comparing base (056a76a) to head (07f8bdc).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ackend/base/langflow/services/tracing/langwatch.py	0.00%	17 Missing ⚠️

❌ Your patch status has failed because the patch coverage (0.00%) is below the target coverage (40.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (39.21%) is below the target coverage (60.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11013      +/-   ##
==========================================
- Coverage   33.11%   33.09%   -0.02%     
==========================================
  Files        1389     1389              
  Lines       65685    65699      +14     
  Branches     9720     9720              
==========================================
- Hits        21750    21742       -8     
- Misses      42821    42843      +22     
  Partials     1114     1114              

Flag	Coverage Δ
backend	52.37% <0.00%> (-0.09%)	⬇️
frontend	15.35% <ø> (ø)
lfx	39.21% <ø> (ø)

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

Files with missing lines	Coverage Δ
...ackend/base/langflow/services/tracing/langwatch.py	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes

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[ogabrielluiz]

why not add this to the instance?

[HzaRashid]

my understanding is (bear with me i'm still unravelling how our tracing works haha), it is expensive to create the tracer_provider each time this class is instantiated, so by tying it to a class variable, subsequent (flow) runs after the first one will have faster tracing setup time for langwatch

[ogabrielluiz]

The tracing service SHOULD be doing that only once, if it isn't that's another bug to fix.

I guess it makes sense to make a class attribute as it gives the best of both worlds.

[HzaRashid]

i think the tracers get lazily initialized on each graph run, will look into it more deeply, this could be a nice performance improvement