Node18环境下AWS Lambda TypeScript部署报错Runtime.ImportModuleError求助

问题描述 #

之前在Node.js 16环境用JavaScript部署AWS Lambda完全正常，现在切换到Node.js 18环境开发TypeScript版本的Lambda函数，通过AWS SAM生成并使用AWS Toolkit部署后，调用函数时出现以下错误：

2023-08-03T14:59:27.311Z undefined ERROR Uncaught Exception
{
"errorType": "Runtime.ImportModuleError",
"errorMessage": "Error: Cannot find module 'index'\nRequire stack:\n- /var/runtime/index.mjs",
"stack": [
"Runtime.ImportModuleError: Error: Cannot find module 'index'",
"Require stack:",
"- /var/runtime/index.mjs",
" at _loadUserApp (file:///var/runtime/index.mjs:997:17)",
" at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1029:21)",
" at async start (file:///var/runtime/index.mjs:1192:23)",
" at async file:///var/runtime/index.mjs:1198:1"
]

用户当前的配置文件如下：

index.ts #

import { APIGatewayProxyEvent, APIGatewayProxyResult } from 'aws-lambda';

export const handler = async (event: APIGatewayProxyEvent): Promise<APIGatewayProxyResult> => {
    try {
        return {
            statusCode: 200,
            body: JSON.stringify({
                message: 'hello world',
            }),
        };
    } catch (err) {
        console.log(err);
        return {
            statusCode: 500,
            body: JSON.stringify({
                message: 'some error happened',
            }),
        };
    }
};

package.json #

{
  "name": "hello_world",
  "version": "0.3.0",
  "description": "",
  "main": "index.ts",
  "scripts": {
    "compile": "tsc"
  },
  "dependencies": {
    "esbuild": "^0.14.14"
  },
  "devDependencies": {
    "@types/aws-lambda": "^8.10.92",
    "@types/node": "^18.11.4",
    "ts-node": "^10.9.1",
    "typescript": "^4.8.4"
  }
}

template.yaml #

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: An AWS Serverless Specification template describing your function.
Resources:
  generateblogpostv1:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: index.handler
      Runtime: nodejs18.x
      CodeUri: .
      Description: ''
      MemorySize: 128
      Timeout: 900
      Role: >-
        arn:aws:iam::921222634505:role/service-role/...
      RuntimeManagementConfig:
        UpdateRuntimeOn: Auto

tsconfig.json #

{
    "compilerOptions": {
      "target": "es2020",
      "strict": true,
      "preserveConstEnums": true,
      "noEmit": true,
      "sourceMap": false,
      "module":"es2015",
      "moduleResolution":"node",
      "esModuleInterop": true, 
      "skipLibCheck": true,
      "forceConsistentCasingInFileNames": true,  
    },
    "exclude": ["node_modules"]
  }

问题原因分析 #

1. TypeScript未编译为JavaScript：tsconfig.json中noEmit设为true，TypeScript编译器不会生成JavaScript文件，而Lambda运行时无法直接执行.ts文件。
2. 入口文件指向错误：package.json的main字段设为index.ts，Lambda运行时需要的是编译后的.js文件。
3. 部署配置未适配编译产物：SAM的CodeUri指向源码目录，未指向编译后的JavaScript文件目录，导致部署包中没有可执行的代码。

解决方案 #

步骤1：修改tsconfig.json，启用编译输出 #

将noEmit改为false，指定输出目录，并调整module为commonjs以适配Node.js运行时：

{
    "compilerOptions": {
      "target": "es2020",
      "strict": true,
      "preserveConstEnums": true,
      "noEmit": false, // 允许生成JS文件
      "outDir": "./dist", // 指定编译产物输出目录
      "sourceMap": false,
      "module":"commonjs", // 切换为commonjs，适配Node.js运行时
      "moduleResolution":"node",
      "esModuleInterop": true, 
      "skipLibCheck": true,
      "forceConsistentCasingInFileNames": true,  
    },
    "exclude": ["node_modules"]
  }

步骤2：更新package.json #

修改main字段指向编译后的入口文件，同时完善编译脚本：

{
  "name": "hello_world",
  "version": "0.3.0",
  "description": "",
  "main": "dist/index.js", // 指向编译后的JS入口
  "scripts": {
    "compile": "tsc",
    "build": "tsc && cp package.json dist/" // 编译后复制package.json到产物目录
  },
  "dependencies": {
    "esbuild": "^0.14.14"
  },
  "devDependencies": {
    "@types/aws-lambda": "^8.10.92",
    "@types/node": "^18.11.4",
    "ts-node": "^10.9.1",
    "typescript": "^4.8.4"
  }
}

步骤3：调整template.yaml的部署配置 #

将CodeUri改为编译后的产物目录：

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: An AWS Serverless Specification template describing your function.
Resources:
  generateblogpostv1:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: index.handler
      Runtime: nodejs18.x
      CodeUri: ./dist/ # 指向编译后的产物目录
      Description: ''
      MemorySize: 128
      Timeout: 900
      Role: >-
        arn:aws:iam::921222634505:role/service-role/...
      RuntimeManagementConfig:
        UpdateRuntimeOn: Auto

步骤4：编译并重新部署 #

1. 执行编译命令生成产物：

npm run build

2. 通过AWS Toolkit重新部署Lambda函数。

可选优化：用SAM自动编译 #

在template.yaml中添加Metadata配置，让SAM部署时自动用esbuild编译TypeScript，无需手动执行编译命令：

Resources:
  generateblogpostv1:
    Type: 'AWS::Serverless::Function'
    Metadata:
      BuildMethod: esbuild
      BuildProperties:
        Minify: true
        Target: es2020
        Sourcemap: false
        EntryPoints:
        - index.ts
    Properties:
      Handler: index.handler
      Runtime: nodejs18.x
      CodeUri: .
      Description: ''
      MemorySize: 128
      Timeout: 900
      Role: >-
        arn:aws:iam::921222634505:role/service-role/...
      RuntimeManagementConfig:
        UpdateRuntimeOn: Auto

内容的提问来源于stack exchange，提问作者laprof