Run k6 test parallely with different environment variables

Grafana k6 OSS Support
2

Not sure I understand your whole question, but I’ll try to give an example where each VU has its own credentials, and you’re not logging in every iteration.

Say you have a JSON file users.js (or many such files, if you parametrize like I explained here) like this:

[
    {
        "username": "user1",
        "password": "pass1"
    },
    {
        "username": "user2",
        "password": "pass2"
    },
    {
        "username": "user3",
        "password": "pass3"
    }
]

Then, you can write your k6 script like this:

import http from "k6/http";
import { sleep } from "k6";

let users = JSON.parse(open(__ENV.MY_USERS_FILE));

export let options = {
    vus: users.length, // VUs stands for "virtual users", after all
    duration: "10s",
};

export function setup() {
    // Transform users into login requests
    let loginRequests = users.map(u => ["POST", "https://httpbin.org/anything", u]);

    // log in all users in parallel
    let loginResponses = http.batch(loginRequests);

    // this is just a demo, but maybe extract some cookies or tokens or whatever in the actual case
    let loginData = loginResponses.map(r => r.json().headers['X-Amzn-Trace-Id']);
    console.log(JSON.stringify(loginData, null, "  "));

    return loginData; // return some array with login details for each user
}

export default function (setupData) {
    let vuData = setupData[__VU - 1]; // Starts from 1
    console.log(`VU ${__VU} is operating with data ` + JSON.stringify(vuData));
    http.get(`https://httpbin.org/anything?userdata=${vuData}`);
    sleep(1);
}

And run it with k6 run --env MY_USERS_FILE=users.json zt.js. Then, each user should only be logged in in the setup() function and you can use their cookies/tokens/whatever in the iteration.

Or, you can use the __ITER execution context variable (until we implement Per-VU init lifecycle function · Issue #785 · grafana/k6 · GitHub) to log in each VU only in their fist iteration, and never again, like this:

export default function () {
    if (__ITER == 0) {
        initVU();
    }
    normalVUCode();
}
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