本地测试Serverless API遇错误：需UserPoolId和ClientId且返回502

问题描述 #

本地用sls offline启动Serverless REST API正常，但发送POST请求创建新用户时返回502 Bad Gateway，后台报错如下：

POST /prod/users (λ: createUser)
Unhandled exception in handler 'createUser'.
Error: Both UserPoolId and ClientId are required.
      at new CognitoUserPool (/node_modules/amazon-cognito-identity-js/lib/CognitoUserPool.js:45:13)
      at Object.<anonymous> (/middlewares/token_middleware.js:11:18)
      at Module._compile (node:internal/modules/cjs/loader:1112:14)
      at Module._extensions..js (node:internal/modules/cjs/loader:1166:10)
      at Module.load (node:internal/modules/cjs/loader:988:32)
      at Module._load (node:internal/modules/cjs/loader:834:12)
      at Module.require (node:internal/modules/cjs/loader:1012:19)
      at require (node:internal/modules/cjs/helpers:102:18)
      at Object.<anonymous> (/handlers/users_handler.js:8:21)
      at Module._compile (node:internal/modules/cjs/loader:1112:14)
Both UserPoolId and ClientId are required.

已在.env文件中声明UserPoolId和ClientId，但报错依然存在。

相关代码 #

token_middleware.js #

const jwt = require("jsonwebtoken"),
  request = require("request"),
  jwkToPem = require("jwk-to-pem"),
  AmazonCognitoIdentity = require("amazon-cognito-identity-js");

const poolData = {
  UserPoolId: process.env.COGNITO_USER_POOL,
  ClientId: process.env.COGNITO_USER_CLIENT,
};
const pool_region = process.env.COGNITO_REGION;
const userPool = new AmazonCognitoIdentity.CognitoUserPool(poolData);

users_handler.js #

"use strict";
const Database = require("../db"),
  User = require("../models/user.model"),
  Usage = require("../models/usage.model"),
  jwt = require("jsonwebtoken"),
  { v4: uuidv4 } = require("uuid"),
  emailService = require("../services/mail.service"),
  tokenMiddleware = require("../middlewares/token_middleware"),
  subWeeks = require("date-fns/subWeeks"),
  querystring = require("querystring"),
  AWS = require("aws-sdk"),
  AmazonCognitoIdentity = require("amazon-cognito-identity-js");

const poolData = {
  UserPoolId: process.env.COGNITO_USER_POOL,
  ClientId: process.env.COGNITO_USER_CLIENT,
};
const pool_region = process.env.COGNITO_REGION;
const userPool = new AmazonCognitoIdentity.CognitoUserPool(poolData);

/* Create User */
module.exports.create = (event, context, callback) => {
  context.callbackWaitsForEmptyEventLoop = false;
  Database.connectToDatabase()
    .then(() => {
      let body = URLSearchParams.decode(event.body);
      const randomKey = uuidv4();
      let newUser = new User({
        firstName: body.firstName,
        lastName: body.lastName,
        email: body.email,
        password: body.password,
        apiKey: randomKey.replace(/-/g, ""),
      });
      newUser.save(function (err, user) {
        if (err) {
          callback(null, {
            statusCode: err.statusCode || 500,
            headers: { "Content-Type": "text/plain" },
            body: err.message,
          });
        } else {
          callback(null, {
            statusCode: 200,
            body: JSON.stringify(user),
          });
        }
      });
    })
    .catch((err) => {
      callback(null, {
        statusCode: err.statusCode || 500,
        headers: { "Content-Type": "text/plain" },
        body: err.message,
      });
    });
};

请求情况 #

通过Postman发送POST请求到/prod/users，请求体为x-www-form-urlencoded格式，包含firstName、lastName、email、password字段。

预期与实际结果 #

预期：创建用户并发送包含API key的确认邮件
实际：返回502 Bad Gateway，后台出现上述UserPoolId和ClientId必填错误

解决办法 #

1. 配置Serverless Offline加载环境变量

   • 安装serverless-dotenv-plugin插件：

     npm install serverless-dotenv-plugin --save-dev
     

   • 在serverless.yml中添加插件配置：

     plugins:
       - serverless-dotenv-plugin
       - serverless-offline
     custom:
       dotenv:
         path: .env # 指定.env文件路径，确保路径正确
     

2. 验证环境变量是否正确注入

   • 在token_middleware.js开头添加日志打印，确认变量是否存在：

     console.log("COGNITO_USER_POOL:", process.env.COGNITO_USER_POOL);
     console.log("COGNITO_USER_CLIENT:", process.env.COGNITO_USER_CLIENT);
     

   • 重启sls offline查看控制台输出，若变量为空，检查.env文件路径或变量名拼写。

3. 修正模块加载阶段的依赖问题

   • 当前代码在模块加载时就实例化CognitoUserPool，若环境变量未及时加载会报错。可延迟实例化逻辑：

     // 修改token_middleware.js
     let userPool;
     function getUserPool() {
       if (!userPool) {
         const poolData = {
           UserPoolId: process.env.COGNITO_USER_POOL,
           ClientId: process.env.COGNITO_USER_CLIENT,
         };
         userPool = new AmazonCognitoIdentity.CognitoUserPool(poolData);
       }
       return userPool;
     }
     module.exports = { getUserPool };
     

   • 在users_handler.js中通过调用getUserPool()获取实例，而非在模块顶部直接实例化。

4. 检查变量名一致性

   • 确保.env文件中的变量名与代码中使用的COGNITO_USER_POOL、COGNITO_USER_CLIENT完全一致，注意大小写敏感。

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