Unable to send xml response with serverless framework

Question

I'm working with twilio in which when call comes to my twilio number it invokes webhook, I'm using lambda function as webhook,

twilio expects xml(formerly called twiml) response from webhook and i'm unable to send xml response from lambda function

I'm using serverless framework

here is my code function:

module.exports.voice = (event, context, callback) => {

  console.log("event", JSON.stringify(event))
  var twiml = new VoiceResponse();

  twiml.say({ voice: 'alice' }, 'Hello, What type of podcast would you like to listen? ');
  twiml.say({ voice: 'alice' }, 'Please record your response after the beep. Press any key to finish.');

  twiml.record({
    transcribe: true,
    transcribeCallback: '/voice/transcribe',
    maxLength: 10
  });

  console.log("xml: ", twiml.toString())

  context.succeed({
    body: twiml.toString()
  });
};

yml:

service: aws-nodejs

provider:
  name: aws
  runtime: nodejs6.10
  timeout: 10

iamRoleStatements:
    - Effect: "Allow"
      Action: "*"
      Resource: "*"

functions:
  voice:
    handler: handler.voice
    events:
      - http:
          path: voice
          method: post
          integration: lambda
          response:
            headers:
              Content-Type: "'application/xml'"
          template: $input.path("$")
          statusCodes:
                200:
                    pattern: '.*' # JSON response
                    template:
                      application/xml: $input.path("$.body") # XML return object
                    headers:
                      Content-Type: "'application/xml'"

Response:

please let me know if I'm making some mistake in code also created an issue on github

Thanks, Inzamam Malik

Answer 1

You don't need to mess with serverless.yml so much. Here is the simple way:

In serverless.yml...

functions:
  voice:
    handler: handler.voice
    events:
      - http:
          path: voice
          method: post

(response, headers, Content-Type, template, and statusCodes are not necessary)

Then you can just set the statusCode and Content-Type in your function.

So delete this part...

context.succeed({
    body: twiml.toString()
  });

... and replace it with:

const response = {
    statusCode: 200,
    headers: {
      'Content-Type': 'text/xml',
    },
    body: twiml.toString(),
};

callback(null, response);

Lambda proxy integration (which is the default) assembles it into a proper response.

Personally I find this way simpler and more readable.

Answer 2

you need your lambda to be a "proxy" type, so you set the body property. but just try to do

context.succeed(twiml.toString());

that will send the "string" as result directly

or use the callback param:

function(event, context, callback) {
   callback(null, twiml.toString())
}