如何为FastAPI的Swagger UI集成Firebase OAuth2登录？

我编写了如下Firebase Auth身份验证中间件，用于从请求头中获取Firebase Token并验证身份：

class AuthenticationMiddleware(BaseHTTPMiddleware):
    """Middleware to authenticate requests using Firebase Auth."""

    async def dispatch(self, request: Request, call_next: Callable):
        # This is where you can modify the request if needed
        path = request.url.path
        # Exclude specific paths from middleware
        if path in [
            "/health",
            "/auth/login",
            "/docs",
            "/openapi.json",
        ]:
            return await call_next(request)  # Continue with the request

        headers = request.headers
        token = headers.get("Authorization")

        if not token:
            raise HTTPException(status_code=401, detail="Authorization token is missing")

        try:
            # Verify and decode the token using Firebase Admin SDK
            user_info = auth.verify_id_token(token)
            # Check if the token is still valid
            if user_info.get("exp") < time.time():
                raise HTTPException(status_code=401, detail="Token expired")
            # If the token is valid, you can access user information
            request.state.user = user_info
            return await call_next(request)  # Continue with the request

        except Exception as err:
            raise HTTPException(status_code=401, detail="Invalid token") from err

目前所有需要Token验证的API都得用Postman或Thunderclient测试，我想把用户友好的OAuth2登录集成到Swagger UI里简化测试，已经看过FastAPI的Simple OAuth2文档，请教怎么适配现有Firebase中间件实现Swagger内无缝Token测试？

要让Swagger UI支持Firebase OAuth2登录，需结合FastAPI安全配置与现有中间件，具体步骤如下：

1. 配置FastAPI的OAuth2安全方案 #

在FastAPI实例初始化时，添加Swagger OAuth2跳转配置，同时基于Firebase的OpenID Connect（OIDC）规则定义安全方案：

from fastapi import FastAPI
from fastapi.security import OAuth2AuthorizationCodeBearer

# 替换为你的Firebase项目信息
FIREBASE_PROJECT_ID = "你的Firebase项目ID"
FIREBASE_WEB_CLIENT_ID = "你的Firebase Web应用客户端ID"

# 定义OAuth2授权码流规则
oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="https://accounts.google.com/o/oauth2/v2/auth",
    tokenUrl=f"https://securetoken.google.com/{FIREBASE_PROJECT_ID}/token",
    scopes={
        "openid": "获取用户身份标识",
        "email": "获取用户邮箱",
        "profile": "获取用户基本信息"
    }
)

# 初始化FastAPI并配置Swagger OAuth2参数
app = FastAPI(
    title="Firebase Auth集成API",
    swagger_ui_oauth2_redirect_url="/docs/oauth2-redirect",
    swagger_ui_init_oauth={
        "clientId": FIREBASE_WEB_CLIENT_ID,
        "appName": "你的测试API",
        "scopes": "openid email profile"
    }
)

2. 调整现有中间件适配Swagger跳转 #

Swagger登录时会用到/docs/oauth2-redirect路径，需将其加入中间件的排除列表，避免被Token验证拦截：

# 修改中间件的路径排除逻辑
if path in [
    "/health",
    "/auth/login",
    "/docs",
    "/openapi.json",
    "/docs/oauth2-redirect"  # 新增该路径
]:
    return await call_next(request)

3. 获取Firebase必要配置信息 #

• Web客户端ID：进入Firebase控制台 → 项目设置 → 应用 → 对应Web应用 → 复制「客户端ID」
• 项目ID：Firebase控制台 → 项目设置 → 常规 → 复制「项目ID」

4. 测试Swagger登录流程 #

启动FastAPI服务后访问/docs：

1. 点击右上角「Authorize」按钮
2. 在弹出的授权窗口中完成Firebase账号登录
3. 登录成功后，Swagger会自动将Token附加到后续API请求头中，直接点击「Try it out」即可测试受保护的接口

注意：本地测试需使用http://localhost地址启动服务，否则可能触发跨域拦截；若部署到线上，需确保API地址已加入Firebase项目的授权域名列表。

内容的提问来源于stack exchange，提问作者ProxilityProblemSolver