wrapper

The wrapper is the main protagonist function of the @serverless-guy/lambda library, it takes a callback (our custom handler function) as a parameter and returns a fully valid AWS Lambda function.

Anatomy of the callback function

The callback function accepted by wrapper is the custom handler of your lambda, below is an example of callback/custom handler function

function handler(request, response) {
  return response({
    okay: true
  });
}

In the example above, the handler function is our callback function. It accepts two parameters, request as first parameter which contains the Lambda’s event and context and response as second parameter, which is a function that would accept 3 parameters.

The first parameter of the default response function is your response body, the second paramter is an optional status code that would defaults to 200 and the third parameter is the optional additional headers.

Full usage example

function handler(request, response) {
  const { event } = request;
  const status = 200;
  const headers = {
    'X-Powered-By': 'Yo momma\'s ass'
  };

  /** return the event body */
  return response({
    ...JSON.parse(event.body || {});
  }, status);
}

Note that the format of event and context is the same as the lambda’s orignal event and context.