AWS API-Gateway communicating to SNS

Question

I am building an API which will be serviced by Lambda functions but I need these to be asynchronous so rather than connecting the API-Gateway directly to the Lambda function

Answer 1

I did eventually get this to work after working with AWS support. Here's my solution:

• First of all even though you're sending a POST you will not be able to send a JSON message in the body of the message as you might expect
• Instead you must URL Encode the JSON and pass it as query parameter
• Also remember that the JSON you send should start with a root object of default which in SNS-world means the "default channel"
• Then, eventually Lambda picks up the SNS event you must also abstract away a lot of the noise to get at your JSON message. For this I created the following function that I use within my Lambda function:

/**
 * When this is run in AWS it is run "through" a SNS
 * event wconfig.ich adds a lot of clutter to the event data,
 * this tests for SNS data and normalizes when necessary
 */
function abstractSNS(e) {
  if (e.Records) {
    return JSON.parse(decodeURIComponent(e.Records[0].Sns.Message)).default;
  } else {
    return e;
  }
}

/**
 * HANDLER
 * This is the entry point for the lambda function
 */
exports.handler = function handler(event, context) {
  parent.event = abstractSNS(event);