AWS Lambda send response to API Gateway

Question

I have a lambda function that generates some text. This is for a simple Twilio app

<Say>Welcome to your conference room!</Say>
<Dial>
   <Conference beep="true">waitingRoom</Conference>
</Dial>

When I make a POST request using postman it outputs exactly that. but I have two problems:

1. The headers comes back at application/json, and I need it as text/xml.
2. When I make the POST request from Twilio I get 502 Bad Gateway

I know it has to do something with the incoming params mapping and also mapping the response from Lambda back to the API Gateway as text/xml. But I can;t figure out how to do this.

Answer 1

I used the following template mapping to basically just strip the quotes and it worked:

---

$input.path('$')

Answer 2

I am glad not to be the only one struggling with AWS Api Gateway :)

As far as I know, AWS Api Gateway is mostly JSON oriented. If you can change the content of the response returned (using JSON), maybe you could resolve your problem :

{"say": "Welcome to your conference room!",
 "dial": [{
        "conference": [{
                "beep": "true",
                "name": "waitingRoom"
        }]
    }
]}

You could then map this content using the mapping template feature (in the Integration response screen), by adding a template with a content-type set to "application/json", and a mapping-template set to :

<Say>$input.json('say')</Say>
<Dial>
    <Conference beep="$input.json('dial.conference.beep')">$input.json('dial.conference.name')</Conference>
</Dial>

Does this help you or I am missing something ?