LangChain

LangChain (and thus LangGraph) has built-in OpenTelemetry tracing via Langsmith which you can use with Logfire. It's enabled by these two environment variables:

LANGSMITH_OTEL_ENABLED=true
LANGSMITH_TRACING=true

Here's a complete example using LangGraph:

import os

import logfire

# These environment variables need to be set before importing langchain or langgraph
os.environ['LANGSMITH_OTEL_ENABLED'] = 'true'
os.environ['LANGSMITH_TRACING'] = 'true'

from langgraph.prebuilt import create_react_agent

logfire.configure()


def add(a: float, b: float) -> float:
    """Add two numbers."""
    return a + b


math_agent = create_react_agent('openai:gpt-4o', tools=[add], name='math_agent')

result = math_agent.invoke({'messages': [{'role': 'user', 'content': "what's 123 + 456?"}]})
print(result['messages'][-1].content)

The resulting trace looks like this in Logfire: