FastAPI OIDC JWKS

A FastAPI dependency used to verify a user's OAuth access token with JWKS.

Installation

pip install fastapi-oidc-jwks

Usage example

from fastapi import FastAPI, APIRouter, Depends
from fastapi_oidc_jwks import AuthDependency

app = FastAPI()

auth = AuthDependency("Your OIDC provider's JWKS URI here")

router = APIRouter(dependencies=[Depends(auth)])

@router.get("/user")
async def handle(user: dict = Depends(auth)):
    return {"user": user}

app.include_router(router)

Options

AuthDependency(jwks_uri, issuer=None, audience=None): the token's iss and aud claims are only checked when issuer and audience are set. With Keycloak, issuer is the realm's URL (e.g. https://keycloak.example.com/realms/myrealm).

Responses:

• 401 if the token is missing, invalid, expired or has no exp claim
• 503 if the JWKS can't be fetched from the identity provider

Verifying a token outside HTTP requests

verify_token returns the token's claims, or raises jwt.PyJWTError. For example, to authenticate Socket.IO connections:

import jwt
import socketio

@sio.event
async def connect(sid, environ, data):
    try:
        auth.verify_token((data or {}).get("token") or "")
    except jwt.PyJWTError:
        raise socketio.exceptions.ConnectionRefusedError("unauthorized")

TokenVerifier(jwks_uri, issuer=None, audience=None) provides verify_token without FastAPI's dependency.

Middleware

AuthMiddleware authenticates every request instead, and puts the token's claims in request.state.user:

from fastapi.middleware.cors import CORSMiddleware
from fastapi_oidc_jwks import AuthMiddleware

app.add_middleware(
    AuthMiddleware,
    jwks_url="Your OIDC provider's JWKS URI here",
    exclude_paths=["/docs", "/openapi.json"],
)
# Added after AuthMiddleware, so that it runs first: 401 responses then get CORS headers too
app.add_middleware(CORSMiddleware, allow_origins=["*"], allow_headers=["*"], allow_methods=["*"])

OPTIONS requests (CORS preflight) and the paths in exclude_paths are passed through without authentication.