Request tracking - Feather

Tracing a failure through the logs is much easier when every line from the same request carries the same ID. Feather adds one, and turns on JSON logging in production.

.env

LOG_LEVEL=INFO        # DEBUG, INFO, WARNING, ERROR, CRITICAL
LOG_FORMAT=json       # enabled automatically when FLASK_ENV=production

Usage

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 reused when present, for distributed tracing
The ID goes into the response headers automatically
Read it with get_request_id() or g.request_id

JSON log format

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

The ID travels in both the response header and every log line, so a user reporting a failure can hand you the header value and you can pull up every line for that request.