Minimum contents of a project for a containerized Lambda

Dockerfile

FROM public.ecr.aws/lambda/nodejs:12

COPY package*.json ./
RUN npm install
COPY index.js ./

CMD [ "index.handler" ]

index.js

module.exports.handler = async (event, context) => {
  return { msg: 'Hello from lambda!' };
};

package.json

{
  "name": "hello-lambda",
  "description": "A containerized lambda example",
  "version": "1.0.0",
  "main": "index.js",
  "author": "Your Name",
  "license": "MIT",
  "repository": "none"
}