> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bryel.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Python

> Trace a Python LLM app or agent — one call, then any OpenInference instrumentor.

`bryel` ships your model calls, tool calls, tokens, and cost to bryel as
OpenInference traces. One call configures OpenTelemetry; then any
[OpenInference instrumentor](https://github.com/Arize-ai/openinference) flows
through — bryel adds no mapping, it's just the exporter.

<Steps>
  <Step title="Install">
    <CodeGroup>
      ```bash uv theme={"theme":{"light":"github-light","dark":"github-dark"}}
      uv add bryel
      ```

      ```bash pip theme={"theme":{"light":"github-light","dark":"github-dark"}}
      pip install bryel
      ```
    </CodeGroup>
  </Step>

  <Step title="Initialize">
    ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
    import bryel
    bryel.init(api_key="bk_…", service_name="my-app")
    ```

    Or read the key from the environment (`BRYEL_KEY`) and omit `api_key`.
  </Step>

  <Step title="Instrument your stack">
    Add the OpenInference instrumentor for your library:

    <CodeGroup>
      ```python OpenAI theme={"theme":{"light":"github-light","dark":"github-dark"}}
      from openinference.instrumentation.openai import OpenAIInstrumentor
      OpenAIInstrumentor().instrument()
      ```

      ```python Anthropic theme={"theme":{"light":"github-light","dark":"github-dark"}}
      from openinference.instrumentation.anthropic import AnthropicInstrumentor
      AnthropicInstrumentor().instrument()
      ```

      ```python LangChain theme={"theme":{"light":"github-light","dark":"github-dark"}}
      from openinference.instrumentation.langchain import LangChainInstrumentor
      LangChainInstrumentor().instrument()
      ```

      ```python LlamaIndex theme={"theme":{"light":"github-light","dark":"github-dark"}}
      from openinference.instrumentation.llama_index import LlamaIndexInstrumentor
      LlamaIndexInstrumentor().instrument()
      ```
    </CodeGroup>

    …or let bryel wire up every instrumentor you have installed:

    ```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
    bryel.init(api_key="bk_…", instrument=True)
    ```
  </Step>

  <Step title="Verify">
    Run a model call, then open the trace explorer — model, tokens, cost, and
    tool calls appear.
  </Step>
</Steps>

## Full example

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
import bryel
bryel.init(service_name="support-agent", instrument=True)  # reads BRYEL_KEY

from openai import OpenAI
OpenAI().chat.completions.create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": "hello"}],
)

bryel.shutdown()  # flush pending spans before exit
```

## Grouping and feedback

Stamp `session.id`, `user.id`, and a `bryel.interaction.id` you mint onto your
spans to group turns into a conversation and join
[feedback](/guides/feedback).

<Note>
  bryel sends OTLP/HTTP protobuf and needs no client-side mapping — the ingest
  normalizes both the OpenInference (`llm.*`) and OpenTelemetry GenAI
  (`gen_ai.*`) conventions.
</Note>

## API

### `bryel.init(api_key=None, *, service_name=None, endpoint=None, headers=None, set_global=True, instrument=False)`

Configures the exporter and returns the OpenTelemetry `TracerProvider`.

<ParamField path="api_key" type="str">Project API key (`bk_…`). Falls back to `$BRYEL_KEY`.</ParamField>
<ParamField path="service_name" type="str">OpenTelemetry `service.name`.</ParamField>
<ParamField path="endpoint" type="str" default="https://ingest.eu.bryel.ai/v1/traces">OTLP/HTTP URL. Override via `$BRYEL_INGEST_URL` for self-hosting.</ParamField>
<ParamField path="headers" type="dict">Extra headers, merged after auth.</ParamField>
<ParamField path="set_global" type="bool" default="True">Register as the global OpenTelemetry provider.</ParamField>
<ParamField path="instrument" type="bool" default="False">Also auto-instrument installed OpenInference libraries.</ParamField>

### `bryel.auto_instrument(tracer_provider=None) -> list[str]`

Best-effort instrument every installed OpenInference library — provider SDKs,
agent SDKs, and frameworks (see [Integrations](/sdk/integrations) for the full
list). Returns the ones it wired up; safe to call with none installed.

### `bryel.shutdown()`

Flush pending spans and shut down. Call on process exit.