Logging setup for FastAPI
This logging setup configures Structlog to output pretty logs in development, and JSON log lines in production.
Then, you can use Structlog loggers or standard
logging loggers, and they both will be processed by the Structlog pipeline (see the
hello() endpoint for reference). That way any log generated by your dependencies will also be processed and enriched, even if they know nothing about Structlog!
Requests are assigned a correlation ID with the
asgi-correlation-id middleware (either captured from incoming request or generated on the fly).
All logs are linked to the correlation ID, and to the Datadog trace/span if instrumented.
This data "global to the request" is stored in context vars, and automatically added to all logs produced during the request thanks to Structlog.
You can add to these "global local variables" at any point in an endpoint with `structlog.contextvars.bind_contextvars(custom