How to use the python LlamaIndexInstrumentor to trace LlamaIndex Workflows
LlamaIndex Workflows are a subset of the LlamaIndex package specifically designed to support agent development.
Our LlamaIndexInstrumentor automatically captures traces for LlamaIndex Workflows agents. If you've already enabled that instrumentor, you do not need to complete the steps below.
pip install openinference-instrumentation-llama_indexInitialize the LlamaIndexInstrumentor before your application code. This instrumentor will trace both LlamaIndex Workflows calls, as well as calls to the general LlamaIndex package.
from openinference.instrumentation.llama_index import LlamaIndexInstrumentor
from phoenix.otel import register
tracer_provider = register()
LlamaIndexInstrumentor().instrument(tracer_provider=tracer_provider)By instrumenting LlamaIndex, spans will be created whenever an agent is invoked and will be sent to the Phoenix server for collection.
Now that you have tracing setup, all invocations of chains will be streamed to your running Phoenix for observability and evaluation.
Sign up for Phoenix:
Sign up for an Arize Phoenix account at https://app.phoenix.arize.com/login
Click Create Space, then follow the prompts to create and launch your space.
Install packages:
pip install arize-phoenix-otelSet your Phoenix endpoint and API Key:
From your new Phoenix Space
Create your API key from the Settings page
Copy your Hostname from the Settings page
In your code, set your endpoint and API key:
import os
os.environ["PHOENIX_API_KEY"] = "ADD YOUR PHOENIX API KEY"
os.environ["PHOENIX_COLLECTOR_ENDPOINT"] = "ADD YOUR PHOENIX HOSTNAME"
# If you created your Phoenix Cloud instance before June 24th, 2025,
# you also need to set the API key as a header:
# os.environ["PHOENIX_CLIENT_HEADERS"] = f"api_key={os.getenv('PHOENIX_API_KEY')}"Launch your local Phoenix instance:
pip install arize-phoenix
phoenix serveFor details on customizing a local terminal deployment, see Terminal Setup.
Install packages:
pip install arize-phoenix-otelSet your Phoenix endpoint:
import os
os.environ["PHOENIX_COLLECTOR_ENDPOINT"] = "http://localhost:6006"See Terminal for more details.
Pull latest Phoenix image from Docker Hub:
docker pull arizephoenix/phoenix:latestRun your containerized instance:
docker run -p 6006:6006 arizephoenix/phoenix:latestThis will expose the Phoenix on localhost:6006
Install packages:
pip install arize-phoenix-otelSet your Phoenix endpoint:
import os
os.environ["PHOENIX_COLLECTOR_ENDPOINT"] = "http://localhost:6006"For more info on using Phoenix with Docker, see Docker.
Install packages:
pip install arize-phoenixLaunch Phoenix:
import phoenix as px
px.launch_app()