python-fastapi-demo

FastAPI StatLite Metrics demo

This runnable application accompanies the canonical FastAPI integration guide. The guide contains the complete copyable integration and explains its field semantics, single-worker scope, and deployment caveats. This directory keeps the helper, application wiring, configuration, and integration test executable together.

Run the demo

From this directory, create an environment and install the pinned runtime dependencies used by the canonical guide:

python3 -m venv .venv
source .venv/bin/activate
python -m pip install -r requirements.txt
uvicorn app:app --host 127.0.0.1 --port 8000 --workers 1

In another terminal, exercise normal, missing, error, and metrics responses:

curl -s http://127.0.0.1:8000/
curl -s -o /dev/null -w '%{http_code}\n' http://127.0.0.1:8000/missing
curl -s -o /dev/null -w '%{http_code}\n' http://127.0.0.1:8000/failure
curl -s http://127.0.0.1:8000/statlite/metrics
statlite inspect 'http://127.0.0.1:8000/statlite/metrics'

From the repository root, start StatLite with the demo configuration:

go run ./cmd/statlite --config examples/python-fastapi-demo/statlite.yaml

Open http://127.0.0.1:9090. The demo polls every 10 seconds for responsive local feedback. Use a 30-second or longer interval in production. Its SQLite file is created under examples/python-fastapi-demo/.

Run the tests

From the repository root, install the test dependency into the active environment and run the FastAPI integration checks:

python -m pip install -r examples/python-fastapi-demo/requirements-test.txt
python -m unittest examples/python-fastapi-demo/test_statlite_metrics.py

The tests exercise FastAPI's actual normal, 404, and unhandled 500 response behavior. They also verify that /statlite/metrics, including a query string, does not increment application counters. Memory is current Python allocation size traced by tracemalloc, not process RSS or a memory limit.