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LlamaIndex is a data framework for connecting LLMs with external data sources. Braintrust traces LlamaIndex applications using OpenTelemetry to capture queries, retrievals, and LLM interactions.

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Setup

This integration uses Braintrust’s Python SDK OpenTelemetry configuration. Install LlamaIndex with OpenTelemetry support: 
pip install "braintrust[otel]" llama-index openai python-dotenv
Configure your environment variables:
.env
BRAINTRUST_API_KEY=your-api-key
BRAINTRUST_PARENT=project_name:llamaindex-demo
OPENAI_API_KEY=your-openai-key

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Trace with LlamaIndex

Configure LlamaIndex’s global handler to send OpenTelemetry traces to Braintrust:
llamaindex_braintrust.py
import os

import llama_index.core
from dotenv import load_dotenv
from llama_index.core.llms import ChatMessage
from llama_index.llms.openai import OpenAI

load_dotenv()

# Configure LlamaIndex to send OTel traces to Braintrust
# Note: "arize_phoenix" is LlamaIndex's OTel handler name.
# We redirect it to Braintrust by overriding the endpoint.
braintrust_api_url = os.environ.get("BRAINTRUST_API_URL", "https://api.braintrust.dev")
llama_index.core.set_global_handler("arize_phoenix", endpoint=f"{braintrust_api_url}/otel/v1/traces")

# Your LlamaIndex application code
messages = [
    ChatMessage(role="system", content="Speak like a pirate. ARRR!"),
    ChatMessage(role="user", content="What do llamas sound like?"),
]
result = OpenAI().chat(messages)
print(result)
LlamaIndex uses "arize_phoenix" as the OpenTelemetry handler name. By overriding the endpoint, traces are sent to Braintrust instead.

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