Support response object results from request handlers

[radhikalism]

Currently, it looks like edgy verifies the result value of a ViewerRequest handler execution by delegating to lib.payloadVerifyRequest() via its ViewerRequest._payloadVerify method implementation. But this does not support response objects coming from viewer request functions (i.e. a short-circuit response, without connecting to the origin).

A viewer request function could yield a response object result, not always a request object result.

When a viewer request handler yields a response object (one with a status field), then lib.payloadVerifyRequest() will fail, and it will cause vReq.execute() to fail.

Example:

const edgy = require('@magnetikonline/edgy');

async function myTest() {
  const vReq = new edgy.ViewerRequest()
  vReq
    .setClientIp('1.2.3.4')
    .setHttpMethod('PUT')
    .setUri('/path/to/api/route')
    .addRequestHttpHeader('X-Fancy-Header','apples')

  const resp = await vReq.execute(
    // Fails request verification because the yielded payload is a response object:
    async function(event) {
      return { status: '302', statusDescription: 'Redirect', headers: {} }
    }
  )
}

Result:

Error: payload property [clientIp] not found
 ❯ payloadPropertyExists node_modules/@magnetikonline/edgy/lib.js:636:8
 ❯ payloadPropertyExistsString node_modules/@magnetikonline/edgy/lib.js:649:2
 ❯ Object.payloadVerifyRequest node_modules/@magnetikonline/edgy/lib.js:420:2
 ❯ ViewerRequest._payloadVerify node_modules/@magnetikonline/edgy/main.js:12:7
 ❯ ViewerRequest.execute node_modules/@magnetikonline/edgy/lib.js:140:8
 ❯ tests/index.test.js:291:20
    289|     .addRequestHttpHeader('X-Fancy-Header','apples')
    290| 
    291|   const response = await vReq.execute(
       |                    ^
    292|     // Fails request verification because the yielded payload is a response object:
    293|     async function(event) {

A workaround:

class ViewerRequest extends edgy.ViewerRequest {
  _payloadVerify(payload) {
     if ('status' in payload) { // Verify a response object result from the viewer request handler:
      edgyLib.payloadVerifyResponse(payload)
    } else { // Verify a request object result from the viewer request handler:
      edgyLib.payloadVerifyRequest(payload)
    }
  }
}

Aside: response object verification requires a headers field, but only a status field is strictly required.

The same problem may be true of OriginRequest too.

Could ViewerRequest and OriginRequest classes support direct response object results?

[magnetikonline]

This is fantastic @radhikalism - thanks for the very detailed writeup and set of AWS documentation links.

Agreed - this should be supported. I'll add it to to backlog of work I'll put into this package. 👍

As always, it's finding the time to get these things done 😄.

[radhikalism]

@magnetikonline Thanks, if it helps, I've pushed a PR at #5 with a possible solution, please check it out whenever you can.

I'd like to use edgy in a project, and while the subclass workaround is adequate for as long as needed, it would be nicer to add upstream support for response objects from request functions. 🙂

[magnetikonline]

For sure @radhikalism - let me see if I can grab some time to put some love into this project - as you can see, got another long standing issue still in the backlog too 😄