kokokenada/k6-load-test-rails

Load Testing

• Seeded from https://github.com/k6io/template-typescript

Generating a New Test Script

This is rudimentary tooling to assist with the generation of load test cases.

The overall strategy is to capture graphql queries issued by the ui, edit the captured queries to be the load test and then run them as a load test.

Some support for REST is also present and has been used to emulate thrid part systems calling a webhook as part of the flow.

Trace - Capture Queries

First turn tracing one by going to the /admin and turning on tracing. This also writes a local storage setting in order that the setting can be retained when sessions are re-started.

Then, perform steps in UI that you want to base the steps on.

Copy Generated Trace JSON into tests/.ts and export as testSteps as appropriate types. E.g.:

export const myFirstTest: Test = {
  testName: 'myFirstTest',
  testSteps: [], // captured JSON goes here
}

The types are vital because it guides the modification of the captured steps to include variability and correctness checks.

Then add the new test to src/tests/tests.ts so that the cli can find the test.

This has captured the raw queries, hard coded variables values and results (which serve as convenient examples when defining your checks)

Refining Queries and Defining Checks

The raw queries are a great starting point as they represent real user activity to the extent your trace capture represents user activity. However, it would not be a realistic system test to if the same user accessed the same results simultaneously.

So we need a way to customize the variables based on the previous results. For example, if a user displays a list of items and clicks one. The item displayed should be one of the items displayed in the list, not the item recorded by the trace capture.

Also, if lets the server refused to process a request due to an authentication problem or perhaps, under load, the server returns incorrect results, how will you know?

To handle both of these issues, you must add some data elements to the captured GraphQL queries to record data retrieved and use it in a future step.

See the comments in src/lib/test-types.ts file for descriptions on how to modify the captured script to be an actual test script.

Dry Run

Before running an actual load test, you can do some basic testing to make sure you have configured the checks and variable settings correctly.

npx ts-node src/cli/ltr.ts --dry-run.ts -t <the name you gave your test>

Setting up a Local Load Test Environment

It is a good idea to make sure your load tests are working targeting a local instance of the app. You can also use much of this setup to load test a cloud instance by using your computer to host the virtual users.

After you have the app up and running locally, install K6

• https://k6.io/docs/getting-started/installation (brew install k6)

Running tests

• Build the tests (transpiles the Typescript so it is ready for k6)

$ npm run build

• There is a test test you can use to ensure k6 is working

$ k6 run dist/test-test.js

• Write configuration files to set target host and # of virtual users. e.g.:

npx ts-node src/cli/ltr.ts --write-config -t signUpAndBuy -h 'http://localhost:3000/ken-dev/api/graphql' 'http://localhost:3000/ken-dev/api/hooks'  -u 50 -m 5

• To see options:

npx ts-node src/cli/ltr.ts

• To run the test

npm run test

Installing Reporting and DataViz

https://k6.io/docs/results-visualization/influxdb-+-grafana

brew install influxdb
brew install grafana

To launchd influxdb and restart at login:

brew services start influxdb
brew services start grafana

Or, if you don't want/need a background service you can just run:

influxd -config /usr/local/etc/influxdb.conf
grafana-server --config=/usr/local/etc/grafana/grafana.ini --homepath /usr/local/share/grafana --packaging=brew cfg:default.paths.logs=/usr/local/var/log/grafana cfg:default.paths.data=/usr/local/var/lib/grafana cfg:default.paths.plugins=/usr/local/var/lib/grafana/plugins

Running and capturing

k6 run --out influxdb=http://localhost:8086/myk6db dist/main.js

Using Graphana

• default id nd password is admin/admin
• create influx db data source (server: http://localhost:8086, db: myk6db)

K6 is not Node

It's great that k6 defines tests in JavaScript and it was a deciding factor in its selection. (Other tools, e.g. artillery use yaml files which are not as expressive or flexible)

However, k6 is written in go and hosts its own JavaScript engine. Don't mistake it for node. You may not be able to import any library.

By default, k6 can only run ES5.1 JavaScript code. To use TypeScript, we have to set up a bundler hat 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] (https://k6.io/docs/using-k6/modules#bundling-node-modules).