Starlette Exporter

Integrating metrics requires just two lines of code: adding the PrometheusMiddleware and exposing the /metrics endpoint, as shown in the FastAPI and Starlette examples in the README.

Defaults to grouping paths by named parameters (e.g., /api/items/{id}), which prevents metric cardinality spikes by aggregating requests, a critical feature highlighted in the documentation.

Allows adding default labels via static values or callbacks, with helpers like from_header for extraction, enabling rich contextual metrics without manual instrumentation as detailed in the Labels section.

Supports adding trace IDs to metrics via exemplars for correlation with tracing systems, though it requires using the handle_openmetrics handler instead of the standard one, as explained in the Exemplars section.