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

# Request tracking

> A unique ID on every request and structured JSON logging, so a production incident is greppable.

```bash .env theme={null}
LOG_LEVEL=INFO        # DEBUG, INFO, WARNING, ERROR, CRITICAL
LOG_FORMAT=json       # auto-enabled when FLASK_ENV=production
```

## Usage

```python theme={null}
from feather import get_request_id

@api.get('/users')
def list_users():
    app.logger.info(f"Listing users [{get_request_id()}]")
    return {'users': [...]}
```

## How it works

* A unique UUID per request
* The incoming `X-Request-ID` header is used if present, for distributed tracing
* The ID is added to response headers automatically
* Available via `get_request_id()` or `g.request_id`

## JSON log format

```json theme={null}
{
  "timestamp": "2024-01-15T10:30:00.000Z",
  "level": "INFO",
  "message": "Listing users",
  "request_id": "abc-123-def",
  "logger": "myapp.routes"
}
```

<Tip>
  Because the request ID travels in both the response header and every log line, a user
  reporting a failure can hand you the header value and you can find every log line for
  that request.
</Tip>