@teleology/lambda-wscore

A Serverless >= 1.38 Lambda Websocket wrapper. Auto parses data, injects a publish method as well as a quick eventType reference.

Installation

npm install @teleology/lambda-wscore

or

yarn add @teleology/lambda-wscore

Usage

Servereless Project

Configure your function to accept all routes/actions.

functions:
  websocket:
    handler: src/index.default
    memorySize: 3008
    events:
      - websocket:
          route: $connect
      - websocket:
          route: $disconnect
      - websocket:
          route: $default

Wrapper

Be aware, you do not need to return anything within the lambda, the library will automatically return a valid response. However for a custom response your handler should return a JSON object with a statusCode.

// pre-ES6
// const lambdaWs = require('@teleology/lambda-ws');

// ES6
import lambdaWs from '@teleology/lambda-wscore';

const handler = async (enhancedEvent) => {
  const { connectionId } = enhancedEvent.requestContext;
  switch (enhancedEvent.action) {
    case 'connect': {
      const token = enhancedEvent.headers.Authorization.replace('Bearer ', '');
      // handle authorization
      break;
    }
    case 'disconnect': {
      console.log('Closing connection to', connectionId);
      break;
    }
    case 'message': {
      const { publish } = enhancedEvent;
      await publish({ message: 'hello from @teleology/lambda-ws' });
      break;
    }
    default: {
      // no-op
      break;
    }
  }
};

export default lambdaWs(handler);

Connection Details

Connection data is needed to re-establish a publish request and can be used outside of the context of the lambda (as long as the connection is still open).

import lambdaWs, { extractConnectionData } from '@teleology/lambda-ws';

export default lambdaWs(async (event) => {
  // Save connectionData for use later
  const connectionData = extractConnectionData(event);
})

Connection Details

If you have stored your connection details somewhere else, you can publish data to a client outside of the websocket lambda.

import { createPublisher } from '@teleology/lambda-ws';

const publishToClient = async (connectionData, message) => {
  const publish = createPublisher(connectionData);

  return publish(message);
}

EnhancedEvent

type Publisher = Function(data: any);

type EnhancedEvent & OriginalEvent {
  action: connect | disconnect | message
  publish: Publisher
  data: JSON | Buffer | string
}