A k6 extension for testing Action Cable and AnyCable functionality. Built for k6 using the xk6 system.
Comparing to the official WebSockets support, xk6-cable
provides the following features:
- Built-in Action Cable API support (no need to manually build or parse protocol messages).
- Synchronous API to initialize connections and subscriptions.
- AnyCable-specific extensions (e.g., binary encodings)
Read also "Real-time stress: AnyCable, k6, WebSockets, and Yabeda"
We also provide JS helpers to simplify writing benchmarks for Rails applications.
To build a k6
binary with this extension, first ensure you have the prerequisites:
- Go toolchain v1.17+
- Git
- Install
xk6
framework for extendingk6
:
go install go.k6.io/xk6/cmd/xk6@latest
- Build the binary:
xk6 build --with github.com/anycable/xk6-cable@latest
# you can specify k6 version
xk6 build v0.42.0 --with github.com/anycable/xk6-cable@latest
# or if you want to build from the local source
xk6 build --with github.com/anycable/xk6-cable@latest=/path/to/source
Consider a simple example using the EchoChannel:
// benchmark.js
import { check, sleep } from 'k6';
import cable from "k6/x/cable";
export default function () {
// Initialize the connection
const client = cable.connect("ws://localhost:8080/cable");
// If connection were not sucessful, the return value is null
// It's a good practice to add a check and configure a threshold (so, you can fail-fast if
// configuration is incorrect)
if (
!check(client, {
"successful connection": (obj) => obj,
})
) {
fail("connection failed");
}
// At this point, the client has been successfully connected
// (e.g., welcome message has been received)
// Send subscription request and wait for the confirmation.
// Returns null if failed to subscribe (due to rejection or timeout).
const channel = client.subscribe("EchoChannel");
// Perform an action
channel.perform("echo", { foo: 1 });
// Retrieve a single message from the incoming inbox (FIFO).
// Returns null if no messages have been received in the specified period of time (see below).
const res = channel.receive();
check(res, {
"received res": (obj) => obj.foo === 1,
});
channel.perform("echo", { foobar: 3 });
channel.perform("echo", { foobaz: 3 });
// You can also retrieve multiple messages at a time.
// Returns as many messages (but not more than expected) as have been received during
// the specified period of time. If none, returns an empty array.
const reses = channel.receiveN(2);
check(reses, {
"received 2 messages": (obj) => obj.length === 2,
});
sleep(1);
// You can also subscribe to a channel asynchrounsly and wait for the confirmation later
// That allows to send multiple subscribe commands at once in a non-blocking way
const channelSubscribed = client.subscribeAsync("EchoChannel", { foo: 1 });
const anotherChannelSubscribed = client.subscribeAsync("EchoChannel", { foo: 2 });
// Wait for the confirmation
channelSubscribed.await();
anotherChannelSubscribed.await();
// Terminate the WS connection
client.disconnect()
}
Example run results:
$ ./k6 run benchmark.js
/\ |‾‾| /‾‾/ /‾‾/
/\ / \ | |/ / / /
/ \/ \ | ( / ‾‾\
/ \ | |\ \ | (‾) |
/ __________ \ |__| \__\ \_____/ .io
execution: local
script: benchmark.js
output: -
scenarios: (100.00%) 1 scenario, 1 max VUs, 10m30s max duration (incl. graceful stop):
* default: 1 iterations for each of 1 VUs (maxDuration: 10m0s, gracefulStop: 30s)
running (00m00.0s), 0/1 VUs, 1 complete and 0 interrupted iterations
default ✓ [======================================] 1 VUs 00m00.0s/10m0s 1/1 iters, 1 per VU
✓ received res
✓ received res2
✓ received 3 messages
✓ received 2 messages
✓ all messages with baz attr
checks...............: 100.00% ✓ 5 ✗ 0
data_received........: 995 B 83 kB/s
data_sent............: 1.2 kB 104 kB/s
iteration_duration...: avg=11.06ms min=11.06ms med=11.06ms max=11.06ms p(90)=11.06ms p(95)=11.06ms
iterations...........: 1 83.850411/s
ws_connecting........: avg=904.62µs min=904.62µs med=904.62µs max=904.62µs p(90)=904.62µs p(95)=904.62µs
ws_msgs_received.....: 9 754.653698/s
ws_msgs_sent.........: 9 754.653698/s
ws_sessions..........: 1 83.850411/s
You can pass the following options to the connect
method as the second argument:
{
headers: {}, // HTTP headers to use (e.g., { COOKIE: 'some=cookie;' })
cookies: "", // HTTP cookies as string (overwrite the value passed in headers if present)
tags: {}, // k6 tags
handshakeTimeoutS: 60, // Max allowed time to initialize a connection
receiveTimeoutMs: 1000, // Max time to wait for an incoming message
logLevel: "info" // logging level (change to debug to see more information)
codec: "json", // Codec (encoder) to use. Supported values are: json, msgpack, protobuf.
}
NOTE: msgpack
and protobuf
codecs are only supported by AnyCable PRO.
More examples could be found in the examples/ folder.
We provide a collection of utils to simplify development of k6 scripts for Rails applications (w/Action Cable or AnyCable):
import {
cableUrl, // reads the value of the action-cable-url (or cable-url) meta value
turboStreamSource, // find and returns a stream name and a channel name from the <turbo-cable-stream-source> element
csrfToken, // reads the value of the csrf-token meta value
csrfParam, // reads the value of the csrf-param meta value
readMeta, // reads the value of the meta tag with the given name
} from 'https://anycable.io/xk6-cable/jslib/k6-rails/0.1.0/index.js'
export default function () {
let res = http.get("http://localhost:3000/home");
if (
!check(res, {
"is status 200": (r) => r.status === 200,
})
) {
fail("couldn't open page");
}
const html = res.html();
const wsUrl = cableUrl(html);
if (!wsUrl) {
fail("couldn't find cable url on the page");
}
let client = cable.connect(wsUrl);
if (
!check(client, {
"successful connection": (obj) => obj,
})
) {
fail("connection failed");
}
let { streamName, channelName } = turboStreamSource(html);
if (!streamName) {
fail("couldn't find a turbo stream element");
}
let channel = client.subscribe(channelName, {
signed_stream_name: streamName,
});
if (
!check(channel, {
"successful subscription": (obj) => obj,
})
) {
fail("failed to subscribe");
}
// ...
}
Bug reports and pull requests are welcome on GitHub at https://github.com/anycable/xk6-cable.
The gem is available as open source under the terms of the MIT License.