[aws-lambda-nodejs] SyntaxError: Support for the experimental syntax 'decorators-legacy' isn't currently enabled

Solution

{
  "presets": [
    "@babel/preset-typescript"
  ],
  "plugins": [
    [
      "@babel/plugin-proposal-decorators",
      {
        "legacy": true
      }
    ]
  ]
}

Original Issue

As of 1.48.0, lambda functions with decorators are broken.

Error: Failed to run bundling Docker image for asset cognito/customMessage/Code/Stage: Error: [Status 1] stdout: Building custom-message.ts...

SyntaxError: Support for the experimental syntax 'decorators-legacy' isn't currently enabled

Reproduction Steps

If it’s not a repro, what the hell is repro?

• custom-message.ts

import * as lambda from 'aws-lambda'
import { boundMethod } from 'autobind-decorator'

type TEvent = lambda.CognitoUserPoolTriggerEvent

/**
 * [UserPool Lambda Triggers](https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-custom-message.html)
 */
class CustomMessageHandler {
  constructor(/* ...dependencies */) {
    // ...
  }
  
  @boundMethod
  public async handle(event: TEvent): Promise<TEvent> {
    switch (event.triggerSource) {
      case 'CustomMessage_SignUp':
        return this.handleSignUp(event)
      case 'CustomMessage_ResendCode':
        return this.handleResendCode(event)
      case 'CustomMessage_ForgotPassword':
        return this.handleForgotPassword(event)
      default:
        throw new Error('Unhandled Trigger')
    }
  }

  ...

  @boundMethod
  protected async handleForgotPassword(event: TEvent): Promise<TEvent> {
    const givenName = event.request.userAttributes['given_name']
    const familyName = event.request.userAttributes['family_name']

    event.response = {
      ...event.response,
      emailSubject: 'Confirmation Code for Forgot Password',
      emailMessage: `
      <div>
        <p>Dear ${givenName} ${familyName},</p>
        <br/>
        <p>Confirmation Code is:</p>
        <p>${event.request.codeParameter}</p>
        <br/>
        <p>Thank you!</p>
      </div>
      `,
    }
    return event
  }
}

export const handle = new CustomMessageHandler(/* ...dependencies */).handle

• stack.ts

import * as cognito from '@aws-cdk/aws-cognito'
import * as lambda from '@aws-cdk/aws-lambda-nodejs'
import * as path from 'path'

const userPool = new cognito.UserPool(this, 'userPool', {
  ...,
  lambdaTriggers: {
    customMessage: new lambda.NodejsFunction(this, 'customMessage', {
      entry: path.resolve(__dirname, 'custom-message.ts'),
      handler: 'handle',
    }),
  },
}

Error Log

$ cdk synth

Error: Failed to run bundling Docker image for asset cognito/customMessage/Code/Stage: Error: [Status 1] stdout: Building custom-message.ts...
🚨 Build failed.


stderr: @parcel/transformer-babel: Support for the experimental syntax 'decorators-legacy' isn't currently enabled (11:3):
SyntaxError: Support for the experimental syntax 'decorators-legacy' isn't currently enabled (11:3):
    at Object._raise (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:757:17)
    at Object.raiseWithData (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:750:17)
    at Object.expectOnePlugin (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:8849:18)
    at Object.parseDecorator (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11385:10)
    at /usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11995:32
    at Object.withTopicForbiddingContext (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11078:14)
    at Object.parseClassBody (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11984:10)
    at Object.parseClass (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11958:22)
    at Object.parseStatementContent (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:11245:21)
    at Object.parseStatementContent (/usr/local/share/.config/yarn/global/node_modules/@babel/parser/lib/index.js:6585:18)
/asset-input/packages/.../lib/cognito/custom-message.ts:11:2
  10 | class CustomMessageHandler {
> 11 |   @boundMethod
>    |  ^
  12 |   public async handle(event: TEvent): Promise<TEvent> {
  13 |     switch (event.triggerSource) {
    at AssetStaging.bundle (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/core/lib/asset-staging.ts:182:13)
    at new AssetStaging (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/core/lib/asset-staging.ts:92:29)
    at new Asset (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/aws-s3-assets/lib/asset.ts:117:21)
    at AssetCode.bind (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/aws-lambda/lib/code.ts:180:20)
    at new Function (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/aws-lambda/lib/function.ts:502:29)
    at new NodejsFunction (/Users/civilizeddev/GitHub/.../node_modules/@aws-cdk/aws-lambda-nodejs/lib/function.ts:62:7)
    at CognitoStack.get userPool (/Users/civilizeddev/GitHub/.../lib/cognito/index.ts:23:24)
Subprocess exited with error 1
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Environment

• CLI Version : aws-cli/2.0.27 Python/3.8.3 Darwin/19.5.0 botocore/2.0.0dev31
• Framework Version: 1.49.1, 1.49.0, 1.48.0
• Node.js Version: 14.5.0
• OS : macos 10.15.5
• Language (Version): TypeScript (3.9.6)

Other

• Parcel 2 should require less manual configuration of Babel to build Typescript (with decorators)

---

This is 🐛 Bug Report

[jogold]

@civilizeddev I won’t go about your rude comments and false accusations here…

If it’s not a repro, what the hell is repro?

This is a repro: https://github.com/jogold/decorator-cdk. Did this out of personal curiosity and because I do care about the NodejsFunction construct being functional and offering a good developer experience (even though the discussion here didn’t make me want to do it). And luckily for you it works with decorators and a Babel config.

My feedbacks as a user were ignored by you second time #8181

Don’t know what you’re talking about… you opened the issue and I almost immediately asked for clarification in order to fix it at some point. Not fixing it as fast as you would like it doesn’t mean ignoring it… Again, it’s not my job, I devote part of my free time to it, this is how open source works…

I hope we can return to a more respectful discussion.

[civilizeddev]

Really?

I want you to pay more attention to end user experience on your work.

I hope you wouldn’t think that I’m the just one having trouble with this.

I don’t want to blame on you even though I wasted all day because of this. (What the hell with parcel2?)

I just want to get this fixed.