starlette_exporter

Prometheus exporter for Starlette and FastAPI.

The middleware collects basic metrics:

Counter: starlette_requests_total
Histogram: starlette_request_duration_seconds

Metrics include labels for the HTTP method, the path, and the response status code.

starlette_requests_total{method="GET",path="/",status_code="200"} 1.0
starlette_request_duration_seconds_bucket{le="0.01",method="GET",path="/",status_code="200"} 1.0

Use the HTTP handler handle_metrics at path /metrics to expose a metrics endpoint to Prometheus.

Usage

pip install starlette_exporter

Starlette

        from starlette.applications import Starlette
        from starlette_exporter import PrometheusMiddleware, handle_metrics

        app = Starlette()
        app.add_middleware(PrometheusMiddleware)
        app.add_route("/metrics", handle_metrics)

        ...

FastAPI

        from fastapi import FastAPI
        from starlette_exporter import PrometheusMiddleware, handle_metrics

        app = FastAPI()
        app.add_middleware(PrometheusMiddleware)
        app.add_route("/metrics", handle_metrics)

        ...

Options

app_name: Sets the value of the app_name label for exported metrics (default: starlette).

group_paths: setting this to True will populate the path label using named parameters (if any) in the router path, e.g. /api/v1/items/{item_id}. This will group requests together by endpoint (regardless of the value of item_id). This option may come with a performance hit for larger routers. Default is False, which will result in separate metrics for different URLs (e.g., /api/v1/items/42, /api/v1/items/43, etc.).

Example:

app.add_middleware(PrometheusMiddleware, app_name="hello_world", group_paths=True)

Developing

git clone https://github.com/stephenhillier/starlette_exporter
cd starlette_exporter
pytest tests

License

Code released under the Apache License, Version 2.0.

Dependencies

https://github.com/prometheus/client_python

https://github.com/encode/starlette

Credits

Starlette - https://github.com/encode/starlette

FastAPI - https://github.com/tiangolo/fastapi

Flask exporter - https://github.com/rycus86/prometheus_flask_exporter

Alternate Starlette exporter - https://github.com/perdy/starlette-prometheus

rcoup/starlette_exporter