Firebase Function报错：无法找到function app的有效端点

问题场景 #

本地模拟器中Firebase Functions可正常运行，但部署后前端调用后端服务时触发错误：Error: Unable to find a valid endpoint for function app。

原始配置文件（firebase.json） #

"hosting": {
    "public": "build",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      },
      {
        "source": "/bigben",
        "function": "bigben",
        "region": "us-central1"
      },
      {
        "source": "/create-customer-portal-session",
        "function": "app"
      }
    ]
  }

原始Functions代码（index.js） #

const functions = require('firebase-functions');
const express = require('express');
const app = express();
const cors = require('cors')({origin: true});
app.use(cors);

exports.app = functions.https.onRequest(app);
exports.bigben = functions.https.onRequest((req, res) => {
  const hours = (new Date().getHours() % 12) + 1  // London is UTC + 1hr;
  res.status(200).send(`<!doctype html>
    <head>
      <title>Time</title>
    </head>
    <body>
      ${'BONG '.repeat(hours)}
    </body>
  </html>`);
});

const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY)

const priceId = 'price_1LaJC1CKMdmWgnyspBbFet9v';

const storeItems = new Map([
    [
    1, { priceInCents: 10000, name: 'Item 1 Name'}
    ],
    [
    2, { priceInCents: 20000, name: 'Item 2 Name'}
    ],
])

app.post("/create-checkout-session", async (req, res) => {
  const cust = req.body.customerId
  const price = req.body.priceId
  const quantity = req.body.students
  const quantityA = Number(quantity)

    try {
      const session = await stripe.checkout.sessions.create({
        payment_method_types: ["card"],
        mode: 'subscription',
        allow_promotion_codes: true,
      customer: cust,  
        line_items: [
          {
            price: price,
            // For metered billing, do not pass quantity
            quantity: quantityA,
          },
        ],
        success_url: `https://learning-platform.web.app/`,
        cancel_url: `https://learning-platform.web.app/`,
      }) 
      res.redirect(session.url);
    } catch (e) {
      res.status(500).json({ error: e.message })
    } 
  })


  app.post('/create-customer-portal-session', async (req, res) => {
    const cust = req.body.customerId
    // Authenticate your user.
    const session = await stripe.billingPortal.sessions.create({
      customer: cust,
    
    });
  console.log(session.url)
   res.redirect(session.url);
  });

部署日志截图 #

问题根源与修复方案 #

1. Rewrite规则顺序错误（直接导致找不到端点） #

Firebase Hosting的rewrite规则按顺序匹配，第一个通配符规则"source": "**"会拦截所有请求，导致后续指向app函数的规则从未被触发。

修复：将通配符规则移到rewrites数组末尾，并为app函数显式指定与部署日志一致的region（此处为us-central1）：

"hosting": {
    "public": "build",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "/bigben",
        "function": "bigben",
        "region": "us-central1"
      },
      {
        "source": "/create-customer-portal-session",
        "function": "app",
        "region": "us-central1"
      },
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }

2. Express未配置请求体解析 #

当前代码未添加请求体解析中间件，导致POST请求中的req.body为undefined，会引发Stripe相关参数错误。

修复：在Express初始化后添加解析中间件：

const express = require('express');
const app = express();
const cors = require('cors')({origin: true});

// 添加请求体解析
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.use(cors);

3. Stripe Portal Session缺少必填参数 #

Stripe的billingPortal.sessions.create方法必须指定return_url，否则会抛出错误。

修复：补充return_url参数：

app.post('/create-customer-portal-session', async (req, res) => {
  const cust = req.body.customerId
  const session = await stripe.billingPortal.sessions.create({
    customer: cust,
    return_url: "https://learning-platform.web.app/" // 添加返回URL
  });
  console.log(session.url)
  res.redirect(session.url);
});

4. 重新部署 #

执行部署命令：

firebase deploy --only functions,hosting

验证 #

部署完成后，前端调用/create-customer-portal-session路径即可正常触发app函数，不会再出现找不到端点的错误。

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