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

# Attributes

> Span attributes available to callbacks in the Apitally SDK for Python.

In the Apitally SDK, each API request is represented by a span. Span attributes contain metadata about the request and response, such as the request path, HTTP method, and response status code.

You can use this metadata to make decisions in [sampling](/sdk-reference/python/v1/sampling#custom-sampling) and [masking](/sdk-reference/python/v1/masking#body-masking-callbacks) callbacks, which receive the `span` object as an argument. Access attributes through `span.attributes`. Individual attributes might be missing, so use `.get()`:

```python {4-5} theme={null}
from opentelemetry.sdk.trace import ReadableSpan

def callback(span: ReadableSpan):
    attributes = span.attributes or {}
    path = attributes.get("url.path")
    # ...
```

## Default attributes

The following attributes are useful for common callback decisions. The list is not exhaustive.

| Attribute                      | Type  | Description                                                     |
| :----------------------------- | :---- | :-------------------------------------------------------------- |
| `http.request.method`          | `str` | HTTP method, e.g. `GET` or `POST`.                              |
| `url.path`                     | `str` | Request path, e.g. `/users/123`.                                |
| `url.query`                    | `str` | Query string without `?`, e.g. `page=2`.                        |
| `user_agent.original`          | `str` | Value of the `User-Agent` header.                               |
| `http.route`                   | `str` | Matched endpoint route pattern, e.g. `/users/{id}`.             |
| `http.response.status_code`    | `int` | HTTP response status code, e.g. `200` or `404`.                 |
| `apitally.consumer.identifier` | `str` | Consumer identifier supplied via `apitally.set_consumer()`.     |
| `apitally.consumer.group`      | `str` | Optional consumer group supplied via `apitally.set_consumer()`. |

## Set custom attributes

Use `apitally.set_request_attribute()` in your request handling code to attach custom metadata to the current request span. These attributes are included in the request trace and available to response-stage sampling and masking callbacks.

```python theme={null}
import apitally

apitally.set_request_attribute("tenant.id", tenant_id)
```