Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

Using k6

Protocols

HTTP/2

Open source

HTTP/2

Overview

HTTP/2.0 is the latest version of the HTTP protocol. It improves significantly upon HTTP/1. Most importantly, it introduces a binary wire protocol with multiplexed streams over a single TCP connection. This solves a long-standing performance issue with HTTP/1.1: head-of-line blocking.

Well, it at least partially solves it. The TCP congestion control mechanisms can interfere with the intended independent nature of the multiplexed streams in cases of lost/dropped packets and retransmission/reassembly. The full solution is to run HTTP/2.0 over UDP, as Google implemented with QUIC.

Additional features of HTTP/2.0

Builtin compression of HTTP headers
Server push
Pipelining of requests
Prioritization of requests

Load testing HTTP/2 with k6

When you make HTTP requests in k6, k6 automatically upgrades the connection to HTTP/2.0 if the server supports it, just like your web browser would.

To check what protocol was used for a particular request, refer to the proto property of the response object.

import http from 'k6/http';
import { check, sleep } from 'k6';

export default function () {
  const res = http.get('https://test-api.k6.io/');
  check(res, {
    'protocol is HTTP/2': (r) => r.proto === 'HTTP/2.0',
  });
  sleep(1);
}

To see the values that the r.proto field can have, refer to the documentation for k6 HTTP.