How to run a k6 script with multiple payloads using fs module?

Question

I'm trying to run a k6 script that uses multiple payloads stored in JSON files. I want to read these files using the fs module and send them as part of my HTTP requests. However, it seems that the fs module is not supported in k6.

I understand that k6 does not support the fs module. How can I achieve the same functionality in k6? Is there an alternative way to load multiple payloads from JSON files in k6?

Answer 1

You can use the open function in the init context. It's recommended to use open in combination with SharedArray to reduce memory consumption.

import { SharedArray } from 'k6/data';

const data = new SharedArray('users', function () {
  // this function *MUST* return an array:
  return JSON.parse(open('./users.json'));
});

export default function() {
  doSomething(data[0]);
}

The SharedArray can only handle arrays, as the name suggests. If your JSON file does not contain a top-level array, but something else, you have to wrap it in a singleton array (an array with a single item): return [JSON.parse(open(…))];.

There's also an expiremental fs module