AWS.ApiGatewayManagementApi() postToConnection is not working

Question

I am trying to send a message to a client connected through the socket by using **AWS.ApiGatewayManagementApi() postToConnection** method. It's working fine in local, but not working in ec2. The only difference is VPC. Is that would be a problem?

var AWS = require('aws-sdk');

var awsGW = new AWS.ApiGatewayManagementApi({
    endpoint: "https://endpoint",
    accessKeyId: "accessKeyId",
    secretAccessKey: "secretAccessKey",
    region: "region"
});

awsGW.postToConnection({
    ConnectionId: 'ConnectionId',
    Data: '{"key1":"msg1","key2":"msg2"}'
}, (err, success) => {
    if (err) {
        console.log('Socket error', err);
    } else {
    }
});

ERROR:

{ ForbiddenException: Forbidden
    at Object.extractError (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/protocol/json.js:51:27)
    at Request.extractError (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/protocol/rest_json.js:55:8)
    at Request.callListeners (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
    at Request.emit (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
    at Request.emit (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/request.js:683:14)
    at Request.transition (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/request.js:22:10)
    at AcceptorStateMachine.runTo (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/state_machine.js:14:12)
    at /home/ubuntu/git/backend/node_modules/aws-sdk/lib/state_machine.js:26:10
    at Request.<anonymous> (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/request.js:38:9)
    at Request.<anonymous> (/home/ubuntu/git/backend/node_modules/aws-sdk/lib/request.js:685:12)
  message: 'Forbidden',
  code: 'ForbiddenException',
  time: 2019-06-10T07:40:02.214Z,
  requestId: 'f4caef03-8b52-11e9-9cc3-91bfe40b8eb0',
  statusCode: 403,
  retryable: false,
  retryDelay: 37.0834357877396 } 

Answer 1

I ran into a similar problem and it was because I was using the wrong endpoint. I was generating it from the event object but on a normal API request, so I was getting an endpoint for a different service (the normal API, and not the websocket).

If your websockets service is deployed to a URL like wss://abcd then your endpoint should be https://abcd.

Answer 2

In my case, there was just an error/undefined value in the endpoint I was using to instantiate the

new AWS.ApiGatewayManagementApi({
    endpoint,
    region,
})

Note: endpoint can provided in 2 forms:

• custom domain name+ base path mapping, for example: wss.my-super-website-with-websocket.com/v1 (where v1 is the configured base path mapping)
• default aws-style url like https://********.execute-api.us-east-5.amazonaws.com/prod where prod is the stage configured in API Gateway.

More importantly, for your debugging purposes, if you get desperate, I found out that you can quite easily log the request made by aws-sdk to make sure you are making the correct request (using the aws cli to try the request is also a good idea): node_modules\aws-sdk\lib\event_listeners.js

function executeSend() {
  var http = AWS.HttpClient.getInstance();
  var httpOptions = resp.request.service.config.httpOptions || {};
  try {
    console.log('event listener execute send', resp.request.httpRequest); // only this line is added
    ...