AWS Amplify PubSub with IoT and Cognito

pubsub.js

/*
In order to subscribe to the AWS IoT topic over WS (over MQQT), 
you have to make sure that your Cognito identity has a proper IoT policy attached to it.

More details and the message from the official AWS support: 
https://github.com/aws/aws-amplify/issues/749

This code shows how you can dynamically attach a policy to the authenticated identity.
Make sure that your Authenticated IAM in the Cognito User Pool has proper IoT permissions. 

I settled on: 
  iot:AttachPolicy
  iot:AttachPrincipalPolicy
  iot:ListPrincipalPolicies
  iot:ListAttachedPolicies
  
And the IoT policy itself has:
  iot:Connect
  iot:Subscribe
  iot:Receive
  
*/
import AWS from 'aws-sdk';
import { Auth, PubSub } from 'aws-amplify';

const credentials = await Auth.currentCredentials();

const iot = new AWS.Iot({
  region: 'us-east-1',
  credentials: Auth.essentialCredentials(credentials)
});

const policyName = '<Your Policy>';
const target = credentials._identityId;

const { policies } = await iot.listAttachedPolicies({ target }).promise();

if (!policies.find(policy => policy.policyName === policyName)) {
  await iot.attachPolicy({ policyName, target }).promise();
}

// safe to call PubSub.subscribe()

Hi! Thanks for this, really helpful - is anyone else getting a CORS error when trying this? I am stuck a couple of days on this CORS error, and I believe calling this code from the react App.js won't work. Any ideas?

Thank you

Hi, I've just come across this problem, did you find a solution? thanks.

Thanks Pavel!

Having same issue with CORS.

I know that some AWS service endpoints don't have CORS enabled on their (server side), and you just won't be able to call the AWS SDK commands from in a browser because of that. Maybe this is one of those cases?

Thanks a bunch! This was the only solution that worked for me after a bunch of debugging.