datasette_auth_github middleware example, from https://simonwillison.net/2019/Jul/14/sso-asgi/

starlette_demo.py

from datasette_auth_github import GitHubAuth
from starlette.applications import Starlette
from starlette.responses import HTMLResponse
import uvicorn

app = Starlette(debug=True)


@app.route("/")
async def homepage(request):
    return HTMLResponse("Hello, {}".format(
        repr(request.scope["auth"])
    ))


authenticated_app = GitHubAuth(
    app,
    client_id="986f5d837b45e32ee6dd",
    client_secret="...",
    require_auth=True,
    allow_users=["simonw"],
)

if __name__ == "__main__":
    uvicorn.run(authenticated_app, host="0.0.0.0", port=8000)