Logging in Python

The standard library's logging module is what almost every library writes to, with hierarchical loggers, handlers and formatters. Even if you prefer another API, configure the standard logger so third-party messages end up in the same place. Loguru replaces that setup with one preconfigured logger, readable colored output, file rotation and detailed tracebacks, which makes it pleasant for applications and scripts.

structlog produces structured logs: each event is a set of key-value pairs that can render as JSON in production and as readable lines in development, and it can wrap the standard library logger. Structured logs are much easier to search and aggregate in a log platform. Logfire, from the Pydantic team, is an observability platform built on OpenTelemetry that collects logs, traces and metrics; its SDK is open source and sends data to the hosted service.