pip install "dynamic-config-py[fastapi]"      # or [litestar] [flask] [quart]
pip install "dynamic-config-py[django]"       # …[drf] and [ninja] for its API layers
pip install "dynamic-config-py[robyn]"        # Experimental
pip install "dynamic-config-py[django-bolt]"  # Experimental, Python 3.12+

from fastapi import Depends, FastAPI
from dynamic_config import DynamicConfig
from dynamic_config_web.fastapi import config_dependency, setup

config = DynamicConfig(Database, key="db").file("config.toml").env("APP_")
app = FastAPI()

setup(app, config)
database = config_dependency(config)


@app.get("/")
def index(db: Database = Depends(database)):
    return {"host": db.host, "pool": db.pool_size}

That is the whole integration. setup loads before the first request, watches while serving and stops on the way out; /healthz, /readyz and /metrics are mounted; and every handler reads the configuration the request began with.

What it does that a dependency function does not

One reading per request, enforced. The engine's own book states the rule — read current() once per request and use that value for the whole request — because a reload landing mid-request would otherwise show one request two configurations. Here it is a contextvars scope opened by the adapter: a second read is the same object, and a read outside a request raises instead of quietly answering with whatever is installed at that instant.

One watcher, however many times the app is built. A second watch() on one configuration is AlreadyExists. uvicorn --reload rebuilds the app on every edit and a test suite builds one per client, so the watcher is leased and counted: the first holder starts it and the last one stops it.

A watcher in every worker. A watcher is a thread, and a thread does not survive fork() — but the engine's registration does, so a gunicorn --preload worker would be refused a new one while nothing was watching. Every lease re-arms itself in the child.

Liveness and readiness as different questions. /healthz never fails on configuration: a process that cannot reload should stop receiving traffic, not be restarted into reading the same broken file. /readyz is where nothing installed, reloads failing and too stale answer 503.

Diagnostics only when you say so. /_config/explain and /_config/check are not mounted at all without a guard — not mounted-and-403, which would tell a scanner they exist.

The seven

Each has a page or a section in the book and a runnable example in examples/; all nine answer the same twelve conformance cases, and where one cannot — Robyn's request scope — the suite says so by name rather than skipping quietly.

What this package is not

It is not a second configuration API. Every value still comes from dynamic-config-py, every diagnostic is the engine's, and the adapters add no cache, no copy and no second source of truth — db.current() is still the read path, and current() here is that read taken once per request.

What you may build on and find unchanged tomorrow is written down: the Compatibility Contract.

License

MIT.