k6 Operator

grafana/k6-operator is a Kubernetes operator for running distributed k6 tests in your cluster.

Read also the complete tutorial to learn more about how to use this project.

Setup

Deploying the operator

Install the operator by running the command below:

$ make deploy

Installing the CRD

The k6 operator includes one custom resource called K6. This will be automatically installed when you do a deployment, but in case you want to do it yourself, you may run the command below:

$ make install

Usage

Two samples are available in config/samples, one for a test script and one for an actual test run.

Adding test scripts

The operator utilises ConfigMaps and LocalFile to serve test scripts to the jobs. To upload your own test script, run the following command to configure through ConfigMap:

ConfigMap

$ kubectl create configmap my-test --from-file /path/to/my/test.js

Note: there is a character limit of 1048576 bytes to a single configmap. If you need to have a larger test file, you'll need to use a volumeClaim or a LocalFile instead

VolumeClaim

There is a sample avaiable in config/samples/k6_v1alpha1_k6_with_volumeClaim.yaml on how to configure to run a test script with a volumeClaim.

If you have a PVC with the name stress-test-volumeClaim containing your script and any other supporting file(s), you can pass it to the test like this:

spec:
  parallelism: 2
  script:
    volumeClaim:
      name: "stress-test-volumeClaim"
      file: "test.js"

Note: the pods will expect to find script files in /test/ folder. If volumeClaim fails, it's the first place to check: the latest initializer pod does not generate any logs and when it can't find the file, it will terminate with error. So missing file may not be that obvious and it makes sense to check it manually. See #143 for potential improvements.

Example directory structure while using volumeClaim

├── test
│   ├── requests
│   │   ├── stress-test.js
│   ├── test.js

In the above example, test.js imports a function from stress-test.js and they would look like this:

// stress-test.js
import stress-test from "./requests/stress-test.js";

export let options = {
      vus: 50,
      duration: '10s'
    };

export default function () {
      stress-test();
}

// stress-test.js
import { sleep, check } from 'k6';
import http from 'k6/http';


export default () => {
  const res = http.get('https://test-api.k6.io');
  check(res, {
    'status is 200': () => res.status === 200,
  });
  sleep(1);
};

LocalFile

There is a sample avaiable in config/samples/k6_v1alpha1_k6_with_localfile.yaml on how to configure to run a test script inside the docker image.

Note: if there is any limitation on usage of volumeClaim in your cluster you can use this option, but always prefer the usage of volumeClaim.

Executing tests

Tests are executed by applying the custom resource K6 to a cluster where the operator is running. The properties of a test run are few, but allow you to control some key aspects of a distributed execution.

# k6-resource.yml

apiVersion: k6.io/v1alpha1
kind: K6
metadata:
  name: k6-sample
spec:
  parallelism: 4
  script:
    configMap:
      name: k6-test
      file: test.js
  separate: false
  runner:
    image: <custom-image>
    metadata:
      labels:
        cool-label: foo
      annotations:
        cool-annotation: bar
    securityContext:
      runAsUser: 1000
      runAsGroup: 1000
      runAsNonRoot: true
    resources:
      limits:
        cpu: 200m
        memory: 1000Mi
      requests:
        cpu: 100m
        memory: 500Mi
  starter:
    image: <custom-image>
    metadata:
      labels:
        cool-label: foo
      annotations:
        cool-annotation: bar
    securityContext:
      runAsUser: 2000
      runAsGroup: 2000
      runAsNonRoot: true

The test configuration is applied using

$ kubectl apply -f /path/to/your/k6-resource.yml

Parallelism

How many instances of k6 you want to create. Each instance will be assigned an equal execution segment. For instance, if your test script is configured to run 200 VUs and parallelism is set to 4, as in the example above, the operator will create four k6 jobs, each running 50 VUs to achieve the desired VU count.

Script

The name of the config map that includes our test script. In the example in the adding test scripts section, this is set to my-test.

Separate

Toggles whether the jobs created need to be distributed across different nodes. This is useful if you're running a test with a really high VU count and want to make sure the resources of each node won't become a bottleneck.

Serviceaccount

If you want to use a custom Service Account you'll need to pass it into both the starter and runner object:

apiVersion: k6.io/v1alpha1
kind: K6
metadata:
  name: <test-name>
spec:
  script:
    configMap:
      name: "<configmap>"
  runner:
    serviceAccountName: <service-account>
  starter:
    serviceAccountName: <service-account>

Runner

Defines options for the test runner pods. This includes:

passing resource limits and requests
passing in labels and annotations
passing in affinity and anti-affinity
passing in a custom image

Starter

Defines options for the starter pod. This includes:

passing in custom image
passing in labels and annotations

k6 outputs

k6 Cloud output

k6 supports output to its Cloud with k6 run --out cloud script.js command. This feature is available in k6-operator as well for subscribed users. Note that it supports only parallelism: 20 or less.

To use this option in k6-operator, set the argument in yaml:

...
  script:
    configMap:
      name: "<configmap>"
  arguments: --out cloud
...

Then uncomment cloud output section in config/default/kustomization.yaml and copy your token from the Cloud there:

# Uncomment this section if you need cloud output and copy-paste your token
secretGenerator:
- name: cloud-token
  literals:
  - token=<copy-paste-token-string-here>
  options:
    annotations:
      kubernetes.io/service-account.name: k6-operator-controller
    labels:
      k6cloud: token

This is sufficient to run k6 with the Cloud output and default values of projectID and name ("k6-operator-test"). For non-default values, extended script options can be used like this:

export let options = {
  ...
  ext: {
    loadimpact: {
      name: 'Configured k6-operator test',
      projectID: 1234567,
    }
  }
};

Cleaning up between test runs

After completing a test run, you need to clean up the test jobs created. This is done by running the following command:

$ kubectl delete -f /path/to/your/k6-resource.yml

Multi-file tests

In case your k6 script is split between more than one JS file, you can simply create a configmap with several data entries like this:

kubectl create configmap scenarios-test --from-file test.js --from-file utils.js

If there are too many files to specify manually, kubectl with folder might be an option:

kubectl create configmap scenarios-test --from-file=./test

Alternatively, you can create an archive with k6:

k6 archive test.js [args]

The above command will create an archive.tar in your current folder unless -O option is used to change the name of the output archive. Then it is possible to put that archive into configmap similarly to JS script:

kubectl create configmap scenarios-test --from-file=archive.tar

In case of using an archive it must be additionally specified in your yaml for K6 deployment:

...
spec:
  parallelism: 1
  script:
    configMap:
      name: "crocodile-stress-test"
      file: "archive.tar" # <-- change here

In other words, file option must be the correct entrypoint for k6 run.

Using extensions

By default, the operator will use grafana/k6:latest as the container image for the test jobs. If you want to use extensions built with xk6 you'll need to create your own image and override the image property on the K6 kubernetes resource. For example, the following Dockerfile can be used to create a container image using https://github.com/grafana/xk6-output-prometheus-remote as an extension:

# Build the k6 binary with the extension
FROM golang:1.18.1 as builder

RUN go install go.k6.io/xk6/cmd/xk6@latest
RUN xk6 build --output /k6 --with github.com/grafana/xk6-output-prometheus-remote@latest

# Use the operator's base image and override the k6 binary
FROM grafana/k6:latest
COPY --from=builder /k6 /usr/bin/k6

If we build and tag this image as k6-prometheus:local, then we can use it as follows:

# k6-resource-with-extensions.yml

apiVersion: k6.io/v1alpha1
kind: K6
metadata:
  name: k6-sample-with-extensions
spec:
  parallelism: 4
  script:
    configMap:
      name: crocodile-stress-test
      file: test.js
  arguments: -o xk6-prometheus-rw
  runner:
    image: k6-prometheus:local
    env:
      - name: K6_PROMETHEUS_RW_SERVER_URL
        value: http://prometheus.somewhere:9090/api/v1/write

Note that we are replacing the test job image (k6-prometheus:latest), passing required arguments to k6 (-o xk6-prometheus-rw), and also setting the environment variable to the runner (K6_PROMETHEUS_RW_SERVER_URL).

Scheduling Tests

While the k6 operator doesn't support scheduling k6 tests directly, the recommended path for scheduling tests is to use the cronjobs object from k8s directly. The cron job should run on a schedule and run a delete and then apply of a k6 object

Running these tests requires a little more setup, the basic steps are:

Create a configmap of js test files (Covered above)
Create a configmap of the yaml for the k6 job
Create a service account that lets k6 objects be created and deleted
Create a cron job that deletes and applys the yaml

Add a configMapGenerator to the kustomization.yaml:

configMapGenerator:
  - name: <test-name>-config
    files:
      - <test-name>.yaml

Then we are going to create a service account for the cron job to use:

This is required to allow the cron job to actually delete and create the k6 objects.

---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: k6-<namespace>
rules:
  - apiGroups:
      - k6.io
    resources:
      - k6s
    verbs:
      - create
      - delete
      - get
      - list
      - patch
      - update
      - watch
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: k6-<namespace>
roleRef:
  kind: Role
  name: k6-<namespace>
  apiGroup: rbac.authorization.k8s.io
subjects:
  - kind: ServiceAccount
    name: k6-<namespace>
    namespace: <namespace>
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: k6-<namespace>

We're going to create a cron job:

# snapshotter.yml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: <test-name>-cron
spec:
  schedule: "<cron-schedule>"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        spec:
          serviceAccount: k6
          containers:
            - name: kubectl
              image: bitnami/kubectl
              volumeMounts:
                - name: k6-yaml
                  mountPath: /tmp/
              command:
                - /bin/bash
              args:
                - -c
                - "kubectl delete -f /tmp/<test-name>.yaml; kubectl apply -f /tmp/<test-name>.yaml"
          restartPolicy: OnFailure
          volumes:
            - name: k6-yaml
              configMap:
                name: <test-name>-config

Uninstallation

Running the command below will delete all resources created by the operator.

$ make delete

cmergenthaler/k6-operator