halfdollanugget/sls-websocket-demo

Diagnostic Serverless Websocket Demo

Diagnostic Serverless Websocket Demo

Issue

When trying to respond to a WS message using the Aws.ApiGatewayManagementApi connector in serverless offline, the connector's TCP connection is refused. However this works fine when deployed to AWS.

Error Message:

Unable to generate socket message Error: connect ECONNREFUSED 127.0.0.1:443
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1137:16) {
  message: 'connect ECONNREFUSED 127.0.0.1:443',
  errno: 'ECONNREFUSED',
  code: 'NetworkingError',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 443,
  region: 'us-east-1',
  hostname: '',
  retryable: true,
  time: 2020-03-17T16:37:57.040Z
}
->StackTrace:
 Error: connect ECONNREFUSED 127.0.0.1:443
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1137:16)

Offending Code:

// See src/connector/apigateway.connector.js
class ApiGatewayConnector {
  constructor() {
    const CONNECTOR_OPTS = {
      apiVersion: '2018-11-29',
      endpoint: CONSTANTS.WEBSOCKET_API_ENDPOINT,
    };
    this._connector = new aws.ApiGatewayManagementApi(CONNECTOR_OPTS);
  }

  get connector() {
    return this._connector;
  }

  async generateSocketMessage(connectionId, data) {
    try {
      // This is the problem call where the Connection is refused
      // when sending a message to a WS client
      return await this._connector
        .postToConnection({
          ConnectionId: connectionId,
          Data: data,
        })
        .promise();
    } catch (error) {
      console.error('Unable to generate socket message', error);
      if (error.stack) {
        console.error('->StackTrace:\n', error.stack);
      }
      if (error.statusCode === 410) {
        console.log(`Removing stale connector ${connectionId}`);
      }
    }
  }
}

To replicate issue:

1. yarn (...obviously)
2. yarn offline - start sls offline
3. Connect to ws://localhost:3001 (I use the Websocket King extension)
   This should connect fine
4. Send a message. My test message is:

{
 "action":"PING"
}

5. Sending this message will trigger the ECONNREFUSED error
6. Can also simultate with yarn client in another terminal

Author

Bryan Vaz (@bryanvaz)