k6 Sandbox

A sandbox for Grafana k6 scripts using TypeScript.

Rationale

While JavaScript is great for a myriad of reasons, one area where it fall short is type safety and developer ergonomics. It's perfectly possible to write JavaScript code that will look OK and behave OK until a certain condition forces the executor into a faulty branch.

While it, of course, still is possible to shoot yourself in the foot with TypeScript as well, it's significantly harder. Without adding much overhead, TypeScript will:

• Improve the ability to safely refactor your code.
• Improve readability and maintainability.
• Allow you to drop a lot of the defensive code previously needed to make sure consumers are calling functions properly.

Prerequisites

• k6
• NodeJS
• Yarn

Install Dependencies

Clone the generated repository on your local machine, move to the project root folder and install the dependencies defined in package.json

yarn install

Running the test

To run a test written in TypeScript, we first have to transpile the TypeScript code into JavaScript and bundle the project

yarn build

yarn watch

Those commands creates the final test files to the ./dist folder, the yarn watch will automatically build the scripts on changes.

Once that is done, we can run our script the same way we usually do, for instance:

k6 run dist/get-200-status.test.js

With results to local Prometheus & Grafana

You can run k6 tests and output the results to Prometheus to visualise the data on Grafana in a local container.

This is an extension with grafana/xk6-output-prometheus-remote.

1. Make sure you have installed Docker Desktop

2. Run the command yarn local-test [test-name] '[k6-test-params]', example:

yarn local-test get-200-status "--vus 2 --duration 10s --env BASE_URL=https://embed.gsudevelopment.com"

1. Visit http://localhost:3000/dashboards to view results output in local Grafana Dashboards.

Writing own tests

House rules for writing tests:

• The test code is located in src folder
• The entry points for the tests need to have ".test.ts" word in the name to distinguish them from auxiliary files. You can change the entry here.

Transpiling and Bundling

By default, k6 can only run ES5.1 JavaScript code. To use TypeScript, we have to set up a bundler that converts TypeScript to JavaScript code.

This project uses Babel and Webpack to bundle the different files - using the configuration of the webpack.config.js file.

If you want to learn more, check out Bundling node modules in k6.