Installation of LitmusChaos on OpenShift
Pre-requisites
OpenShift 3.11 or later.
Getting Started
Running chaos on your application involves the following steps:
Install Litmus
oc apply -f https://litmuschaos.github.io/litmus/litmus-operator-v1.13.8.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
Expected output:
chaos-operator-ce-554d6c8f9f-slc8k 1/1 Running 0 6m41s
- Verify if chaos CRDs are installed
oc get crds | grep chaos
Expected output:
chaosengines.litmuschaos.io 2020-05-14T011:22:45Z
chaosexperiments.litmuschaos.io 2020-05-14T011:22:46Z
chaosresults.litmuschaos.io 2020-05-14T011:22:46Z
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
Expected output:
chaosengines litmuschaos.io true ChaosEngine
chaosexperiments litmuschaos.io true ChaosExperiment
chaosresults litmuschaos.io true ChaosResult
NOTE:
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-delete, container-kill,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/master?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
into a 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.
NOTE:
- 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.
Replace nginx with the name of your deployment.
oc annotate deploy/nginx litmuschaos.io/chaos="true" -n nginx
Prepare ChaosEngine
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 applabel , appns, appkind and experiments as per your choice.
Change the 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'
Run Chaos
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 Pass or Fail.
NOTE: ChaosResult CR name will be <chaos-engine-name>-<chaos-experiment-name>
oc describe chaosresult nginx-chaos-container-kill -n nginx
Uninstallation
You can uninstall Litmus by deleting the namespace.
oc delete -f https://litmuschaos.github.io/litmus/litmus-operator-v1.13.8.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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