Crate opentelemetry_langfuse 

OpenTelemetry integration for Langfuse.

This crate provides OpenTelemetry components and utilities for integrating with Langfuse, enabling comprehensive observability for LLM applications.

For detailed information about OpenTelemetry support in Langfuse, see the official documentation.

Quick Start

use opentelemetry_langfuse::ExporterBuilder;
use opentelemetry_sdk::trace::{
    span_processor_with_async_runtime::BatchSpanProcessor,
    SdkTracerProvider,
};
use opentelemetry_sdk::{runtime::Tokio, Resource};
use opentelemetry::KeyValue;
use opentelemetry::global;

// Create the Langfuse exporter from environment variables
// Requires: LANGFUSE_HOST, LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY
let exporter = ExporterBuilder::from_env()?.build()?;

// Create your tracer provider with the Langfuse exporter
let provider = SdkTracerProvider::builder()
    .with_span_processor(BatchSpanProcessor::builder(exporter, Tokio).build())
    .with_resource(Resource::builder().with_attributes(vec![
        KeyValue::new("service.name", "my-service"),
    ]).build())
    .build();

// Set as global provider
global::set_tracer_provider(provider);

// Use the tracer
let tracer = global::tracer("my-tracer");
// ... your tracing code here ...

// Provider will be shutdown when it goes out of scope

Components

Exporter

• Configured OTLP/HTTP exporter for sending traces to Langfuse
• Automatic authentication header setup
• Environment variable configuration support
• Builder pattern for custom configuration

Environment Variables

This crate uses Langfuse-specific environment variables for configuration:

• LANGFUSE_HOST: Base URL of your Langfuse instance (defaults to https://cloud.langfuse.com)
• LANGFUSE_PUBLIC_KEY: Your Langfuse public key (required)
• LANGFUSE_SECRET_KEY: Your Langfuse secret key (required)

Example:

export LANGFUSE_HOST="https://cloud.langfuse.com"
export LANGFUSE_PUBLIC_KEY="pk-lf-..."
export LANGFUSE_SECRET_KEY="sk-lf-..."

Use ExporterBuilder::from_env() to create an exporter using these variables.

Re-exports

pub use auth::build_auth_header;

pub use auth::build_auth_header_from_env;

pub use context::LangfuseContext;

pub use endpoint::build_otlp_endpoint;

pub use endpoint::build_otlp_endpoint_from_env;

pub use error::Error;

pub use error::Result;

pub use exporter::exporter;

pub use exporter::ExporterBuilder;

Modules

auth

Authentication utilities for Langfuse.

constants

Constants for the opentelemetry-langfuse library.

context

Langfuse context helpers for setting trace attributes.

endpoint

Endpoint URL utilities for Langfuse.

error

Error types for the opentelemetry-langfuse library.

exporter

Langfuse OTLP exporter configuration.