simplest hello world AWS Lambda runing nodejs failing /var/runtime/Runtime.js:67:14

Question

I have very little experience on this stack and I've tried several google searches. I didn't find anything!

I'm trying to build a function as simple as possible. A "hello world" style, without compiling the docker container;

This is what I have done ...

docker-compose.yml

version: '3.7'

volumes:
  lambda-node:
    driver: local

services:
  lambda-node:
    image: amazon/aws-lambda-nodejs:12
    environment:
      - STAGE=${STAGE:-local}
    ports:
      - 9000:8080
    volumes:
      - ./src/node:/var/task
    command:
      - app.handler

./src/node/app.js

exports.handler = async (event, context) => {
    console.log(event);
    console.log(context);
    return "{\"message\": \"Hello World.\"}";
}

./src/node/package.json

{
  "name": "node",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

PS: I tried:

• Multiple return options, using or not using JSON.stringify and several other attempts, so I don't believe it's the return itself. To me it seams the script is not event been loaded;
• Generate a package-lock.json
• I started using TAG 14.2022.02.01.09 then I started using TAG 14 and finally I'm doing tests with TAG 10. They all generate the same result
• I even try to run the script as a module!

The output

$ docker-compose up
Starting magma_lambda-node_1 ... done
Attaching to magma_lambda-node_1
lambda-node_1  | 22 Feb 2022 12:20:09,249 [INFO] (rapid) exec '/var/runtime/bootstrap' (cwd=/var/task, handler=)
lambda-node_1  | 22 Feb 2022 12:20:16,280 [INFO] (rapid) extensionsDisabledByLayer(/opt/disable-extensions-jwigqn8j) -> stat /opt/disable-extensions-jwigqn8j: no such file or directory
lambda-node_1  | 22 Feb 2022 12:20:16,280 [WARNING] (rapid) Cannot list external agents error=open /opt/extensions: no such file or directory
lambda-node_1  | START RequestId: e9449065-e27d-444a-b5f0-200ed50bb9b8 Version: $LATEST
lambda-node_1  | 2022-02-22T12:20:16.432Z       e9449065-e27d-444a-b5f0-200ed50bb9b8    ERROR   Invoke Error    {"errorType":"SyntaxError","errorMessage":"Unexpected end of JSON input","stack":["SyntaxError: Unexpected end of JSON input","    at JSON.parse (<anonymous>)","    at Runtime.handleOnce (/var/runtime/Runtime.js:67:14)"]}
lambda-node_1  | END RequestId: e9449065-e27d-444a-b5f0-200ed50bb9b8
lambda-node_1  | REPORT RequestId: e9449065-e27d-444a-b5f0-200ed50bb9b8 Init Duration: 0.35 ms  Duration: 160.00 ms     Billed Duration: 161 ms Memory Size: 3008 MB    Max Memory Used: 3008 MB

Sorry advance for the words! But dud, am I disappointed ...

Can anybody tell me what on earth am I doing wrong?

Thanks