SAM Typescript Lambda Beta Feature - How to Enable Local Debugging?

[patricktran]

I am trying to debug my TS Lambda, but my breakpoints never hit. Can someone please help?

I am using the SAM CLI beta feature as described here:
https://aws.amazon.com/blogs/compute/building-typescript-projects-with-aws-sam-cli/

nodejs14.x – TypeScript
Hello World Example

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: hello-world/
      Handler: app.lambdaHandler
      Runtime: nodejs14.x
      Architectures:
        - x86_64
      Environment:
        Variables:
          NODE_OPTIONS: "--enable-source-maps"
      Events:
        HelloWorld:
          Type: Api 
          Properties:
            Path: /hello
            Method: get
    Metadata: 
      BuildMethod: esbuild
      BuildProperties:
        Minify: true
        Target: "es2020"
        Sourcemap: true 
        EntryPoints:
          - app.ts

VSCode launch.json

{
  "configurations": [
    {
      "type": "aws-sam",
      "request": "direct-invoke",
      "invokeTarget": {
        "target": "template",
        "logicalId": "HelloWorldFunction",
        "templatePath": "/Volumes/projects/ts-lambda/template.yaml"
      },
      "lambda": {
        "runtime": "nodejs14.x"
      },
      "sam": {
        "containerBuild": false,
        "skipNewImageCheck": false
      },
      "api": {
        "httpMethod": "get"
      },
      "name": "hello-world:app.lambdaHandler (nodejs14.x)"
    }
  ]
}

[dnafication]

Can you try removing NODE_OPTIONS: "--enable-source-maps" from env settings to see if that works? The way sam cli enters debug mode is by using the same env variable. If that works, you could possible use the following for entering debug mode.

NODE_OPTIONS: "--enable-source-maps --inspect-brk=0.0.0.0:9229 --max-http-header-size 81920"

[patricktran]

I'm not sure if there is a better way, but I haven't seen an official answer from the AWS team.

This is what I ended up doing and it works:

1. In my package.json, I added a compile script command which essentially runs esbuild and outputs the bundle to a /debug folder
2. Updated my configuration in launch.json to use the /debug folder as the projectRoot

{
  "configurations": [
    {
      "name": "Debug - HelloWorld",
      "type": "aws-sam",
      "request": "direct-invoke",
      "invokeTarget": {
        "target": "code",
        "lambdaHandler": "app.lambdaHandler",
        "projectRoot": "${workspaceFolder}/hello-world/debug"
      },
      "lambda": {
        "runtime": "nodejs14.x",
        "environmentVariables": {},
        "payload": {
          "path": "${workspaceFolder}/events/event.json"
        }
      },
      "sam": {
        "containerBuild": false,
        "skipNewImageCheck": false
      },
      "api": {
        "httpMethod": "get"
      }
    }
  ]
}