Serverless WebSocket example

This is an example of how to send and receive WebSocket messages using a serverless stack. The WebSocket connections are managed by a GRIP-compatible proxy such as Pushpin or Fanout Cloud, and the backend logic is handled by a function backend such as Microcule or AWS Lambda.

Any message sent from a client is relayed to all other connected clients.

Setup using Pushpin and Microcule

Set up virtualenv:

$ virtualenv venv
$ . venv/bin/activate
$ pip install -r requirements.txt

Run the backend:

$ microcule handler-microcule.py

Run pushpin:

$ pushpin -m --route "* localhost:3000,over_http"

Connect:

$ wscat -c ws://localhost:7999
connected (press CTRL+C to quit)
> hello
  < hello

Setup using Fanout Cloud and AWS Lambda

First create a realm in Fanout Cloud and note the realm ID and key.

Set up virtualenv:

$ virtualenv venv
$ . venv/bin/activate
$ pip install -r requirements.txt

Create the deployment package:

$ ./make-lambda-package.sh

Upload lambda-package.zip to AWS Lambda, using the Python 2.7 runtime, and handler-lambda.handler as the handler. Also, set the GRIP_URL environment variable containing Fanout Cloud settings, of the form:

https://api.fanout.io/realm/your-realm?iss=your-realm&key=base64:your-realm-key

Next, set up an API and resource in AWS API Gateway to point to the Lambda function, using a Lambda Proxy Integration, and add application/websocket-events as a Binary media type.

Finally, edit the Fanout Cloud domain origin server (SSL) to point to the host and port of the AWS API Gateway Invoke URL.

Connect:

$ wscat -c ws://{your-fanout-domain}/{your-api-gateway-path}/
connected (press CTRL+C to quit)
> hello
  < hello