Pseudocode for achieving sticky websockets on AWS using per-instance EIPs vended over HTTP.

client.js

function connect() {
  // Since we'd have sticky HTTP sessions, this will always go to the same instance,
  // thus the websocket will connect to the same instance, assuming it's still living.
  $.get('/websocket')
    .then(function(ipAddress) {
      Websocket.connect(ipAddress);
    });
}

Websocket.on('disconnection', connect);

server.js

// Not sure if this could be an environment variable or would have to be fetched
// like instance metadata.
var MY_EIP;

app.get('/websocket', function(req, res) {
  res.send(MY_EIP);
});