Using turborepo to build minimal lambdas with CDK

nodejs-lambda-construct.ts

import * as path from "path";
import * as cdk from "aws-cdk-lib";
import {
  Function as LambdaFunction,
  IFunction,
  Runtime,
  Code,
} from "aws-cdk-lib/aws-lambda";
import { Construct } from "constructs";
import { BundlingOutput, Duration } from "aws-cdk-lib";
import pkgjson from "../../../package.json"; // root package.json

export interface LocalNodeLambdaProps {
  functionName: string;
  functionDescription?: string;
  pkg: string; // package name of the yarn workspace with the code for the lambda function
  timeout: Duration;
  memorySize: number;
  rootDir: string; // directory for the root of the projects. this directory contains a package.json with the workspaces key
  env?: Record<string, string>;
}

export class LocalNodeLambda extends Construct {
  public readonly fn: IFunction;

  constructor(scope: Construct, id: string, props: LocalNodeLambdaProps) {
    super(scope, id);

    const runtime = Runtime.NODEJS_16_X;

    this.fn = new LambdaFunction(this, props.functionName, {
      description: props.functionDescription,
      runtime,
      timeout: props.timeout,
      memorySize: props.memorySize,
      environment: {
        AWS_NODEJS_CONNECTION_REUSE_ENABLED: "1",
        ...props.env,
      },
      code: Code.fromAsset(props.rootDir, {
        bundling: {
          image: runtime.bundlingImage,
          // let cdk zip for us
          outputType: BundlingOutput.NOT_ARCHIVED,
          // npm and yarn really don't like to run without a home directory. just gives error code 243 without one. so run as root and then drop to user account
          user: "0",
          command: [
            "bash",
            "-c",
            [
              `npm install --location=global ${pkgjson.packageManager}`,
              `/sbin/useradd --uid 1000 --create-home node`,
              `su --login node`,
              `yarn --cwd '${cdk.AssetStaging.BUNDLING_INPUT_DIR}' install --frozen-lockfile`,
              `yarn --cwd '${cdk.AssetStaging.BUNDLING_INPUT_DIR}' run prune --scope=${props.pkg}`,
              `echo 'module.exports = require("${props.pkg}");' > '${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out/index.js'`,
              `yarn --cwd '${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out' install --frozen-lockfile`,
              `yarn --cwd '${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out' run build`,
              `yarn --cwd '${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out' install --production --ignore-scripts --prefer-offline --frozen-lockfile`,
              `mv ${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out/* '${cdk.AssetStaging.BUNDLING_OUTPUT_DIR}'`,
              `rm -rf "${cdk.AssetStaging.BUNDLING_INPUT_DIR}/out"`,
            ].join(" && "),
          ],
        },
      }),
      handler: "index.handler",
    });
  }
}

package.json

{
  "name": "...",
  "version": "...",
  "description": "this is the root pakage.json",
  "private": true,
  "packageManager": "yarn@1.22.19",
  "workspaces": [
    "cdk",
    "lambdas/*",
    "common/*"
  ],
  "scripts": {
    "build": "turbo run build",
    "test": "turbo run test",
    "cdk": "yarn workspace @scope/cdk cdk",
    "prune": "run(){ turbo prune $@ && cp tsconfig.json out/tsconfig.json; }; run",
    "prettier": "turbo run prettier"
  },
  "devDependencies": {
    "@types/jest": "^29.1.1",
    "@types/node": "^18.8.2",
    "eslint": "^8.24.0",
    "jest": "^29.1.2",
    "prettier": "^2.7.1",
    "ts-jest": "^29.0.3",
    "ts-node": "^10.9.1",
    "turbo": "^1.5.5",
    "typescript": "^4.8.4"
  }
}