Best Practices on Krkn

Getting Started

Mon, 01 Jan 0001 00:00:00 +0000

Getting Started with Krkn-AI

This documentation details how to deploy a sample microservice application on Kubernetes Cluster and run Krkn-AI test.

Prerequisites

Follow this guide to install Krkn-AI CLI.
Krkn-AI uses Thanos Querier to fetch SLO metrics by PromQL. You can easily install it by setting up prometheus-operator in your cluster.

Deploy Sample Microservice

For demonstration purpose, we will deploy a sample microservice called robot-shop on the cluster:

Adding New Scenario to Krkn-hub

Mon, 01 Jan 0001 00:00:00 +0000

Adding/Editing a New Scenario to Krkn-hub

Create folder with scenario name under krkn-hub
Create generic scenario template with environment variables

a. See scenario.yaml for example

b. Almost all parameters should be set using a variable (these will be set in the env.sh file or through the command line environment variables)
Add defaults for any environment variables in an “env.sh” file

a. See env.sh for example
Create script to run.sh chaos scenario a. See run.sh for example

Getting Started

Mon, 01 Jan 0001 00:00:00 +0000

TL;DR

# 1. Install krknctl
curl -fsSL https://raw.githubusercontent.com/krkn-chaos/krknctl/refs/heads/main/install.sh | bash

# 2. Create a test workload
kubectl create namespace chaos-test
kubectl create deployment nginx-test --image=nginx --replicas=3 -n chaos-test

# 3. Run your first chaos scenario (pod disruption)
krknctl run pod-scenarios --namespace chaos-test --pod-label "app=nginx-test" --disruption-count 1

# 4. Verify pods recovered
kubectl get pods -n chaos-test -l app=nginx-test

What you need

Requirement	Minimum Version	Check Command
Kubernetes or OpenShift cluster	1.21+	`kubectl version`
kubeconfig with cluster-admin access	—	`kubectl get nodes`
Docker or Podman	Docker 20.10+ / Podman 4.0+	`docker --version` or `podman --version`

Basic Run

This is the best starting point if you are new to Krkn or want to explore a specific scenario quickly. No metrics, no scoring, no pipeline — just run a scenario and see what happens.

Running a Chaos Scenario with Krkn

Mon, 01 Jan 0001 00:00:00 +0000

Getting Started Running Chaos Scenarios

Config

Instructions on how to setup the config and all the available options supported can be found at Config.

In all the examples below you’ll replace the scenario_type with the scenario plugin type that can be found in the second column here

Running a Single Scenario

To run a single scenario, you’ll edit the krkn config file and only have 1 item in the list of chaos_scenarios

Setting Up Disconnected Environment

Mon, 01 Jan 0001 00:00:00 +0000

Getting Started Running Chaos Scenarios in a Disconnected Environment

Mirror following images on the bastion host

quay.io/krkn-chaos/krkn-hub:node-scenarios-bm - Master/worker node disruptions on baremetal
quay.io/krkn-chaos/krkn-hub:network-chaos - Network disruptions/traffic shaping
quay.io/krkn-chaos/krkn-hub:pod-scenarios - Pod level disruptions and evaluating recovery time/availability
quay.io/krkn-chaos/krkn-hub:syn-flood - Generates substantial amount of traffic/half open connections targeting a service
quay.io/krkn-chaos/krkn-hub:node-cpu-hog - Hogs CPU on the target nodes
quay.io/krkn-chaos/krkn-hub:node-io-hog - Hogs IO on the target nodes
quay.io/krkn-chaos/krkn-hub:node-memory-hog - Hogs memory on the target nodes
quay.io/krkn-chaos/krkn-hub:pvc-scenarios - Fills up a given PersistentVolumeClaim
quay.io/krkn-chaos/krkn-hub:service-hijacking - Simulates fake HTTP response for a service
quay.io/krkn-chaos/krkn-hub:power-outages - Shuts down the cluster and turns it back on
quay.io/krkn-chaos/krkn-hub:container-scenarios - Kills a container via provided kill signal
quay.io/krkn-chaos/krkn-hub:application-outages - Isolates application Ingress/Egress traffic
quay.io/krkn-chaos/krkn-hub:time-scenarios - Tweaks time/date on the nodes
quay.io/krkn-chaos/krkn-hub:pod-network-chaos - Introduces network chaos at pod level
quay.io/krkn-chaos/krkn-hub:node-network-filter - Node ip traffic filtering
quay.io/krkn-chaos/krkn-hub:pod-network-filter - DNS, internal/external service outages

Will also need these mirrored images inside the cluster

Network disruptions - quay.io/krkn-chaos/krkn:tools
Hog scenarios ( CPU, Memory and IO ) - quay.io/krkn-chaos/krkn-hog
SYN flood - quay.io/krkn-chaos/krkn-syn-flood:latest
Pod network filter scenarios - quay.io/krkn-chaos/krkn-network-chaos:latest
Service hijacking scenarios - quay.io/krkn-chaos/krkn-service-hijacking:v0.1.3

How to Mirror

The strategy is simple:

Git Help For Contributions

Mon, 01 Jan 0001 00:00:00 +0000

How to contribute

Contributions are always appreciated.

How to:

Pull request

In order to submit a change or a PR, please fork the project and follow instructions:

$ git clone http://github.com/<me>/krkn-hub
$ cd krkn-hub
$ git checkout -b <branch_name>
$ <make change>
$ git add <changes>
$ git commit -a
$ <insert good message>
$ git push

Squash Commits

If there are multiple commits, please rebase/squash multiple commits before creating the PR by following:

Adding to Krkn Test Suite

Mon, 01 Jan 0001 00:00:00 +0000

This guide covers how to add both unit tests and functional tests to the krkn project. Tests are essential for ensuring code quality and preventing regressions.

Unit Tests

Unit tests in krkn are located in the tests/ directory and use Python’s unittest framework with comprehensive mocking to avoid requiring external dependencies like cloud providers or Kubernetes clusters.

Creating a Unit Test

1. File Location and Naming

Place your test file in the tests/ directory with the naming pattern test_<feature>.py:

License Header & Pre-Commit

Mon, 01 Jan 0001 00:00:00 +0000

License Header & Pre-Commit

Krkn enforces Apache 2.0 license headers on all Python files using a pre-commit hook. Contributors must have this set up before submitting pull requests.

Setup (one-time)

pip install pre-commit
pre-commit install

Check license headers manually

python scripts/check_license.py

Auto-fix all missing headers

python scripts/check_license.py --fix

Run via pre-commit against all files

pre-commit run check-license-header --all-files

Testing your changes

Mon, 01 Jan 0001 00:00:00 +0000

This page gives details about how you can get a kind cluster configured to be able to run on krkn-lib (the lowest level of krkn-chaos repos) up through krknctl (our easiest way to run and highest level repo)

Configure Kind Testing Environment

Install kind
Create cluster using kind-config.yml under krkn-lib base folder