OpenShift 3.11 or later.
Running chaos on your application involves the following steps:
oc apply -f https://litmuschaos.github.io/litmus/litmus-operator-v1.13.3.yaml
The above command install all the CRDs, required service account configuration, and chaos-operator. Before you start running a chaos experiment, verify if Litmus is installed correctly.
Verify your installation
- Verify if the ChaosOperator is running
oc get pods -n litmus
chaos-operator-ce-554d6c8f9f-slc8k 1/1 Running 0 6m41s
- Verify if chaos CRDs are installed
oc get crds | grep chaos
Verify if the chaos api resources are successfully created in the desired (application) namespace.
Note: Sometimes, it can take a few seconds for the resources to be available post the CRD installation
oc api-resources | grep chaos
chaosengines litmuschaos.io true ChaosEngine
chaosexperiments litmuschaos.io true ChaosExperiment
chaosresults litmuschaos.io true ChaosResult
In this guide, we shall describe the steps to inject container-kill chaos on an nginx application already deployed in the nginx namespace. It is a mandatory requirement to ensure that the chaos custom resources (chaosexperiment and chaosengine) and the experiment specific serviceaccount are created in the same namespace (typically, the same as the namespace of the application under test (AUT), in this case nginx). This is done to ensure that the developers/users of the experiment isolate the chaos to their respective work-namespaces in shared environments.
In all subsequent steps, please follow these instructions by replacing the nginx namespace and labels with that of your application.
Install Chaos Experiments
Chaos experiments contain the actual chaos details. These experiments are installed on your cluster as OpenShift CRs. The Chaos Experiments are grouped as Chaos Charts and are published on Chaos Hub.
The generic chaos experiments such as
pod-network-latency are available under Generic Chaos Chart.
This is the first chart you are recommended to install.
oc apply -f https://hub.litmuschaos.io/api/chaos/1.13.3?file=charts/generic/experiments.yaml -n nginx
Verify if the chaos experiments are installed.
oc get chaosexperiments -n nginx
Setup Service Account
A service account should be created to allow chaosengine to run experiments in your application namespace. Copy the following
rbac.yaml manifest and run
oc apply -f rbac.yaml to create one such account on the nginx namespace. This serviceaccount
has just enough permissions needed to run the pod-delete chaos experiment.
- For rbac samples corresponding to other experiments such as, say, container-kill, please refer the respective experiment folder in the chaos-charts repository.
apiVersion: v1 kind: ServiceAccount metadata: name: pod-delete-sa namespace: nginx labels: name: pod-delete-sa apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: name: pod-delete-sa namespace: nginx labels: name: pod-delete-sa rules: - apiGroups: [""] resources: ["pods","events"] verbs: ["create","list","get","patch","update","delete","deletecollection"] - apiGroups: [""] resources: ["pods/exec","pods/log","replicationcontrollers"] verbs: ["create","list","get"] - apiGroups: ["batch"] resources: ["jobs"] verbs: ["create","list","get","delete","deletecollection"] - apiGroups: ["apps"] resources: ["deployments","statefulsets","daemonsets","replicasets"] verbs: ["list","get"] - apiGroups: ["apps.openshift.io"] resources: ["deploymentconfigs"] verbs: ["list","get"] - apiGroups: ["argoproj.io"] resources: ["rollouts"] verbs: ["list","get"] - apiGroups: ["litmuschaos.io"] resources: ["chaosengines","chaosexperiments","chaosresults"] verbs: ["create","list","get","patch","update"] apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: pod-delete-sa namespace: nginx labels: name: pod-delete-sa roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: pod-delete-sa subjects: - kind: ServiceAccount name: pod-delete-sa namespace: nginx
Annotate your application
Your application has to be annotated with
litmuschaos.io/chaos="true". As a security measure, and also as a means
to reduce blast radius the ChaosOperator checks for this annotation before invoking chaos experiment(s) on the application.
nginx with the name of your deployment.
oc annotate deploy/nginx litmuschaos.io/chaos="true" -n nginx
ChaosEngine connects the application instance to a Chaos Experiment. Copy the following YAML snippet into a file called
chaosengine.yaml and update the values of
experiments as per your choice.
chaosServiceAccount to the name of service account created in above previous steps.
apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: nginx-chaos namespace: nginx spec: annotationCheck: 'true' engineState: 'active' appinfo: appns: 'nginx' applabel: 'run=nginx' appkind: 'deploymentconfig' chaosServiceAccount: pod-delete-sa # use retain to keep the job for debug jobCleanUpPolicy: 'delete' experiments: - name: pod-delete spec: components: env: - name: TOTAL_CHAOS_DURATION value: '30'
Override Default Chaos Experiments Variables
From LitmusChaos v1.1.0, the default environment variable values in chaosexperiments can be overridden by specifying
them in the chaosengine under
experiments.<experiment_name>.spec.components.env with the desired value. In the
example below, the TOTAL_CHAOS_DURATION is being set to a desired value based on the application instance.
... experiments: - name: container-kill spec: components: env: - name: TOTAL_CHAOS_DURATION value: '30'
oc apply -f chaosengine.yaml
Observe Chaos results
Describe the ChaosResult CR to know the status of each experiment. The
spec.verdict is set to
Awaited when the experiment is in progress, eventually changing to either
NOTE: ChaosResult CR name will be
oc describe chaosresult nginx-chaos-container-kill -n nginx
You can uninstall Litmus by deleting the namespace.
oc delete -f https://litmuschaos.github.io/litmus/litmus-operator-v1.13.3.yaml
More Chaos Experiments
- For more details on supported chaos experiments and the steps to run them, refer the Experiments section.
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