部署AWS Lambda Stack时遇Cannot Find Asset错误求助

问题背景 #

尝试部署包含Lambda函数的AWS CDK栈，Lambda运行代码位于source目录下的services文件夹中，但执行cdk synth时触发Cannot Find Asset错误，调整文件位置、添加.js后缀均未解决。

相关代码 #

CDK栈代码（TypeScript） #

import { Stack, StackProps } from "aws-cdk-lib";
import { Construct } from "constructs";
import {
  Code,
  Function as LambdaFunction,
  Runtime,
} from "aws-cdk-lib/aws-lambda";
import { join } from "path";

export class LambdaStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);

    new LambdaFunction(this, "getBooksLambda", {
      runtime: Runtime.NODEJS_18_X,
      handler: "getBooks.main",
      code: Code.fromAsset(join(__dirname, "..", "..", "services", "getBooks")),
    });
  }
}

Lambda函数代码（JavaScript） #

exports.main = async function(event, context) {
    return {
        statusCode: 200,
        body: JSON.stringify({
            message: "Hello from Lambda"
        })
    }
}

报错信息 #

Error: Cannot find asset at C:\Users\User\Documents\Bookeroo\bookeroo-cdk\src\services\getBooks
    at new AssetStaging (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\aws-cdk-lib\core\lib\asset-staging.js:1:2119)
    at new Asset (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\aws-cdk-lib\aws-s3-assets\lib\asset.js:1:1141)
    at AssetCode.bind (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\aws-cdk-lib\aws-lambda\lib\code.js:5:3487)
    at new Function (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\aws-cdk-lib\aws-lambda\lib\function.js:1:10003)
    at new LambdaStack (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\src\infra\stacks\LambdaStack.ts:13:32)
    at Object.<anonymous> (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\src\infra\Launcher.ts:12:1)
    at Module._compile (node:internal/modules/cjs/loader:1241:14)
    at Module.m._compile (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\ts-node\src\index.ts:1618:23)
    at Module._extensions..js (node:internal/modules/cjs/loader:1295:10)
    at Object.require.extensions.<computed> [as .ts] (C:\Users\User\Documents\Bookeroo\bookeroo-cdk\node_modules\ts-node\src\index.ts:1621:12)

问题分析与解决步骤 #

从报错路径C:\Users\User\Documents\Bookeroo\bookeroo-cdk\src\services\getBooks可以看出，CDK尝试在src目录下查找services文件夹，但你明确说明代码位于source目录下——路径计算错误是核心问题。

1. 修正Asset路径 #

当前CDK代码中，__dirname指向的是CDK栈文件所在的src/infra/stacks目录，join(__dirname, "..", "..", "services", "getBooks")会定位到src/services/getBooks，但实际代码在项目根目录下的source/services/getBooks。

调整路径计算，从当前栈文件往上回溯到项目根目录，再指向source目录：

code: Code.fromAsset(join(__dirname, "../../../source/services/getBooks")),

2. 验证路径正确性 #

可以在代码中临时添加路径打印，确认计算后的路径是否匹配实际文件位置：

const lambdaCodePath = join(__dirname, "../../../source/services/getBooks");
console.log("Lambda代码路径：", lambdaCodePath); // 运行时查看输出是否正确

3. 确认文件/目录存在 #

• 确保source/services/getBooks目录（或getBooks.js文件，如果是单个文件的话）确实存在于项目根目录，与src目录同级。
• 如果getBooks是单个文件而非目录，路径需要指向具体的.js文件：

  code: Code.fromAsset(join(__dirname, "../../../source/services/getBooks.js")),
  

内容的提问来源于stack exchange，提问作者Roy Craver