What is Namespaced Mode?
Namespaced mode is the other end of the orchestration spectrum & is an antithesis of the admin-mode of operation. Here, the ChaosOperator as well as the chaos resources (chaosexperiment, chaosengine, chaosresult CRs and the experiment pods) are run in the same namespace where the application under test (AUT) resides. This mode serves the usecases where the developers/users don't typically have much autonomy over cluster usage and operate strictly within a specific allotted namespace. However, in this case too, the cluster-admin or an equivalent user with the right permissions are required to install them CRDs upfront.
Note that this mode of operation restricts the scope of chaos experiments to those at the pod-level, as the node/infra level experiments need cluster-wide access.
How to use Namespaced Mode?
In order to use Namespaced Mode, you just have to install the namespace-scoped litmus operator manifest in the desired (app) namespace. This installs the ChaosOperator, configured to watch for ChaosEngine resources in the same namespace while also setting up the RBAC that can be used for execution of the standard (generic suite) of chaos experiments.
Setup the Namespace-Scoped Chaos Operator
Install the chaos CRDs separately via an admin account
kubectl apply -f https://raw.githubusercontent.com/litmuschaos/litmus/master/docs/litmus-namespaced-scope/litmus-namespaced-crds.yaml
Install the namespace-scoped operator (& continue to operator subsequent steps) via the dev/user account
Pull the manifest from here
Replace the 'default' string with that of your desired namespace across the manifest
Apply the modified operator manifest
kubectl apply -f <namespace-scoped-operator.yaml>
Install the ChaosExperiment CR
The supported experiments in the namespaced-mode, today, are:
Pull the respective chaosexperiment custom resources from the ChaosHub
Prepare the ChaosEngine CR
- Create a chaosengine, similar to the one shown below, by providing the appropriate application & experiment information.
apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: nginx-chaos namespace: default spec: appinfo: appns: 'default' applabel: 'app=nginx' appkind: 'deployment' annotationCheck: 'true' engineState: 'active' chaosServiceAccount: litmus monitoring: false jobCleanUpPolicy: 'delete' experiments: - name: pod-delete spec: components: env: # set chaos duration (in sec) as desired - name: TOTAL_CHAOS_DURATION value: '30' # set chaos interval (in sec) as desired - name: CHAOS_INTERVAL value: '10' # pod failures without '--force' & default terminationGracePeriodSeconds - name: FORCE value: 'false'
Create the ChaosEngine Resource
Create the ChaosEngine manifest prepared in the previous step to trigger the Chaos.
kubectl apply -f chaosengine.yml
Watch Chaos Engine
Describe Chaos Engine for chaos steps. Append your respective namespace to this command.
kubectl describe chaosengine nginx-chaos
Watch Chaos progress
View pod terminations & recovery by setting up a watch on the pods in the application namespace
watch -n 1 kubectl get pods
Check Chaos Experiment Result
Check whether the application is resilient to the chaos injected, once the experiment (job) is completed. The ChaosResult resource name is derived like this:
<ChaosEngine-Name>-<ChaosExperiment-Name>. Append your respective namespace to this command.
kubectl describe chaosresult nginx-chaos-pod-delete