使用AWS CDK仅用mssql却遇knex相关打包错误，求解决

我仅使用mssql客户端，但执行cdk synth时出现如下打包错误：

环境版本信息 #

• Node.js - v18.16.0
• CDK - 2.95.1
• knex - 2.5.1

错误日志 #

dirname /.../my-repo/cdk/my-app/lib/lambda
Bundling asset api---app/get-last-sales-no/Code/Stage...
✘ [ERROR] Could not resolve "sqlite3"

    node_modules/knex/lib/dialects/sqlite3/index.js:42:19:
      42 │     return require('sqlite3');
         ╵                    ~~~~~~~~~

  You can mark the path "sqlite3" as external to exclude it from the bundle, which will remove this
  error. You can also surround this "require" call with a try/catch block to handle this failure at
  run-time instead of bundle-time.

✘ [ERROR] Could not resolve "pg"

    node_modules/knex/lib/dialects/pgnative/index.js:13:19:
      13 │     return require('pg').native;
         ╵                    ~~~~

  You can mark the path "pg" as external to exclude it from the bundle, which will remove this
  error. You can also surround this "require" call with a try/catch block to handle this failure at
  run-time instead of bundle-time.

✘ [ERROR] Could not resolve "mysql2"

    node_modules/knex/lib/dialects/mysql2/index.js:15:19:
      15 │     return require('mysql2');
         ╵                    ~~~~~~~~

  You can mark the path "mysql2" as external to exclude it from the bundle, which will remove this
  error. You can also surround this "require" call with a try/catch block to handle this failure at
  run-time instead of bundle-time.

✘ [ERROR] Could not resolve "pg"

    node_modules/knex/lib/dialects/redshift/index.js:44:19:
      44 │     return require('pg');
         ╵                    ~~~~

  You can mark the path "pg" as external to exclude it from the bundle, which will remove this
  error. You can also surround this "require" call with a try/catch block to handle this failure at
  run-time instead of bundle-time.

查阅资料发现，部分用户通过为esbuild标记knex或客户端依赖为外部依赖解决了问题，但并未直接使用esbuild，推测AWS CDK在底层使用它，请问有什么解决办法？

解决办法 #

AWS CDK的NodejsFunction默认使用esbuild进行打包，你可以通过以下方式配置打包选项，将未使用的数据库驱动标记为外部依赖，让esbuild跳过它们的解析和打包：

方法1：在NodejsFunction中配置externalModules #

直接在Lambda函数定义里添加打包配置，指定不需要打包的依赖：

import { NodejsFunction } from 'aws-cdk-lib/aws-lambda-nodejs';

new NodejsFunction(this, 'GetLastSalesNoFunction', {
  entry: './lib/lambda/get-last-sales-no.ts',
  bundling: {
    // 将未安装的数据库驱动以及knex本身标记为外部依赖
    externalModules: ['sqlite3', 'pg', 'mysql2', 'knex']
  }
});

方法2：通过esbuild配置文件全局设置 #

在项目根目录创建esbuild.config.js，添加外部依赖配置，CDK的NodejsFunction会自动读取该文件：

module.exports = {
  external: ['sqlite3', 'pg', 'mysql2']
};

方法3：自定义Bundling配置（适用于非NodejsFunction场景） #

如果使用的是基础的Function类配合资产打包，可在BundlingOptions中通过命令传递esbuild参数：

import { Function, Code, Runtime } from 'aws-cdk-lib/aws-lambda';

new Function(this, 'GetLastSalesNoFunction', {
  runtime: Runtime.NODEJS_18_X,
  code: Code.fromAsset('./lib/lambda', {
    bundling: {
      image: Runtime.NODEJS_18_X.bundlingImage,
      command: [
        'bash', '-c',
        'npm install && npx esbuild index.ts --bundle --external:sqlite3 --external:pg --external:mysql2 --outfile=/asset-output/index.js'
      ]
    }
  }),
  handler: 'index.handler'
});

原理说明 #

Knex在源码中包含了所有数据库驱动的导入逻辑，即使你只使用MSSQL，esbuild打包时会扫描所有require语句并尝试解析依赖。将未安装的驱动标记为外部依赖后，esbuild会跳过这些依赖的打包，运行时Knex会动态加载你实际使用的MSSQL驱动，不会影响功能。

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