K6 Websocket disconnects after 15 seconds

Question

I’m having trouble running a K6 websocket for more than 15 seconds on 1 VU.

The code is from the documentation:

const socketUrl = `${resBody.url.replace('https', 'wss')}&id=${connectionId}`;

res = ws.connect(socketUrl, params, function (socket) {
    socket.on('open', function() {
        console.log('connected');
        
        socket.setInterval(function timeout() {
            socket.ping();
        }, 1000); 
        
        var payload = JSON.stringify({
            'protocol': 'json',
            'version': 1
        });
        socket.send(payload);           
    });
    socket.on('message', (data) => console.log('Message received: ', data));
    socket.on('close', () => console.log('disconnected'));
    socket.on('error', (e) => console.log('Error: ', e.error()));
    socket.on('ping',  function() {
        console.log('ping');
        socket.pong();
    });
    socket.on('pong', () => console.log('pong'));
    socket.on('priceupdates', (data) => console.log('PriceUpdates: ', data));

    socket.setTimeout(function () {
        console.log('Timeout');
        socket.close();
    }, 1000 * 60 * 100);
});
    
check(res, { 'status is 101': (r) => r && r.status === 101 });

Run command:

k6 run --vus 1 --iterations 1 --duration 1m --min-iteration-duration 30s live_prices.js

And the output:

score 0 · Answer 1 · answered May 20 '22 at 06:41

Found that we need to send a handshake message right after the connection is established

var payload = JSON.stringify({
  'protocol': 'json',
  'version': 1
});

but with Record Ending char (ASCII char 30) at the end.

So I ended up sending:

const endOfRecord = String.fromCharCode(30);

var payload = JSON.stringify({
  'protocol': 'json',
  'version': 1
}) + endOfRecord;

After that everything started working properly.

K6 Websocket disconnects after 15 seconds

1 Answers1