Cassandra Pod Delete Experiment Details
Experiment Metadata
Type | Description | Tested K8s Platform |
---|---|---|
Cassandra | Fail the Cassandra statefulset pod | GKE, Konvoy(AWS), Packet(Kubeadm), Minikube, EKS |
Prerequisites
- Ensure that the Litmus Chaos Operator is running by executing
kubectl get pods
in operator namespace (typically,litmus
).If not, install from here - Ensure that the
cassandra-pod-delete
experiment resource is available in the cluster by executingkubectl get chaosexperiments
in the desired namespace. If not, install from here
Entry Criteria
Cassandra pods are healthy before chaos injection
The load should be distributed on the each replicas.
Exit Criteria
Cassandra pods are healthy post chaos injection
The load should be distributed on the each replicas.
Details
- Causes (forced/graceful) pod failure of specific/random replicas of an cassandra statefulset
- Tests cassandra sanity (replica availability & uninterrupted service) and recovery workflow of the cassandra statefulset.
- The pod delete by
Powerfulseal
is only supporting single pod failure (kill_count = 1)
Integrations
- Pod failures can be effected using one of these chaos libraries:
litmus
,powerfulseal
- The desired chaos library can be selected by setting one of the above options as value for the env variable
LIB
Steps to Execute the Chaos Experiment
This Chaos Experiment can be triggered by creating a ChaosEngine resource on the cluster. To understand the values to provide in a ChaosEngine specification, refer Getting Started
Follow the steps in the sections below to create the chaosServiceAccount, prepare the ChaosEngine & execute the experiment.
Prepare chaosServiceAccount
- Use this sample RBAC manifest to create a chaosServiceAccount in the desired (app) namespace. This example consists of the minimum necessary role permissions to execute the experiment.
- The RBAC sample manifest is different for both LIB (litmus, powerseal). Use the respective rbac sample manifest on the basis of LIB ENV.
Sample Rbac Manifest for litmus LIB
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: cassandra-pod-delete-sa
namespace: default
labels:
name: cassandra-pod-delete-sa
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
metadata:
name: cassandra-pod-delete-sa
namespace: default
labels:
name: cassandra-pod-delete-sa
rules:
- apiGroups: ["","litmuschaos.io","batch","apps"]
resources: ["pods","deployments","statefulsets","services","pods/log","pods/exec","events","jobs","chaosengines","chaosexperiments","chaosresults"]
verbs: ["create","list","get","patch","update","delete"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
name: cassandra-pod-delete-sa
namespace: default
labels:
name: cassandra-pod-delete-sa
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: cassandra-pod-delete-sa
subjects:
- kind: ServiceAccount
name: cassandra-pod-delete-sa
namespace: default
Sample Rbac Manifest for powerfulseal LIB
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: cassandra-pod-delete-sa
namespace: default
labels:
name: cassandra-pod-delete-sa
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
name: cassandra-pod-delete-sa
labels:
name: cassandra-pod-delete-sa
rules:
- apiGroups: ["","litmuschaos.io","batch","apps"]
resources: ["pods","deployments","statefulsets","pods/log","pods/exec","services","events","jobs","configmaps","chaosengines","chaosexperiments","chaosresults"]
verbs: ["create","list","get","patch","update","delete"]
- apiGroups: [""]
resources: ["nodes"]
verbs: ["get","list"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: cassandra-pod-delete-sa
labels:
name: cassandra-pod-delete-sa
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cassandra-pod-delete-sa
subjects:
- kind: ServiceAccount
name: cassandra-pod-delete-sa
namespace: default
Prepare ChaosEngine
- Provide the application info in
spec.appinfo
- Override the experiment tunables if desired in
experiments.spec.components.env
- To understand the values to provided in a ChaosEngine specification, refer ChaosEngine Concepts
Supported Experiment Tunables
Variables | Description | Specify In ChaosEngine | Notes |
---|---|---|---|
CASSANDRA_SVC_NAME | Cassandra Service Name | Mandatory | Defaults value: cassandra |
KEYSPACE_REPLICATION_FACTOR | Value of the Replication factor for the cassandra liveness deploy | Mandatory | It needs to create keyspace while checking the livenss of cassandra |
CASSANDRA_PORT | Port of the cassandra statefulset | Mandatory | Defaults value: 9042 |
CASSANDRA_LIVENESS_CHECK | It allows to check the liveness of the cassandra statefulset | Optional | It can be`enabled` or `disabled` |
CASSANDRA_LIVENESS_IMAGE | Image of the cassandra liveness deployment | Optional | Default value: litmuschaos/cassandra-client:latest |
TOTAL_CHAOS_DURATION | The time duration for chaos insertion (seconds) | Optional | Defaults to 15s |
CHAOS_INTERVAL | Time interval b/w two successive pod failures (sec) | Optional | Defaults to 5s |
KILL_COUNT | No. of cassandra pods to be deleted | Optional | Default to `1`, kill_count > 1 is only supported by litmus lib , not by the powerfulseal |
LIB | The chaos lib used to inject the chaos | Optional | Defaults to `litmus`. Supported: `litmus`, `powerfulseal` |
FORCE | Application Pod deletion mode. `False` indicates graceful deletion with default termination period of 30s. 'True' indicates an immediate forceful deletion with 0s grace period | Optional | Default to `true`, With `terminationGracePeriodSeconds=0` |
RAMP_TIME | Period to wait before injection of chaos in sec | Optional | |
INSTANCE_ID | A user-defined string that holds metadata/info about current run/instance of chaos. Ex: 04-05-2020-9-00. This string is appended as suffix in the chaosresult CR name. | Optional | Ensure that the overall length of the chaosresult CR is still < 64 characters |
Sample ChaosEngine Manifest
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: cassandra-chaos
namespace: default
spec:
appinfo:
appns: 'default'
applabel: 'app=cassandra'
appkind: 'statefulset'
# It can be true/false
annotationCheck: 'true'
# It can be active/stop
engineState: 'active'
#ex. values: ns1:name=percona,ns2:run=nginx
auxiliaryAppInfo: ''
chaosServiceAccount: cassandra-pod-delete-sa
monitoring: false
# It can be delete/retain
jobCleanUpPolicy: 'delete'
experiments:
- name: cassandra-pod-delete
spec:
components:
env:
# set chaos duration (in sec) as desired
- name: TOTAL_CHAOS_DURATION
value: '15'
# set chaos interval (in sec) as desired
- name: CHAOS_INTERVAL
value: '15'
# pod failures without '--force' & default terminationGracePeriodSeconds
- name: FORCE
value: 'false'
# provide cassandra service name
# default service: cassandra
- name: CASSANDRA_SVC_NAME
value: 'cassandra'
# provide the keyspace replication factor
- name: KEYSPACE_REPLICATION_FACTOR
value: '3'
# provide cassandra port
# default port: 9042
- name: CASSANDRA_PORT
value: '9042'
# SET THE CASSANDRA_LIVENESS_CHECK
# IT CAN BE `enabled` OR `disabled`
- name: CASSANDRA_LIVENESS_CHECK
value: ''
Create the ChaosEngine Resource
Create the ChaosEngine manifest prepared in the previous step to trigger the Chaos.
kubectl apply -f chaosengine.yml
If the chaos experiment is not executed, refer to the troubleshooting section to identify the root cause and fix the issues.
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 -n <application-namespace>
Abort/Restart the Chaos Experiment
To stop the pod-delete experiment immediately, either delete the ChaosEngine resource or execute the following command:
kubectl patch chaosengine <chaosengine-name> -n <namespace> --type merge --patch '{"spec":{"engineState":"stop"}}'
To restart the experiment, either re-apply the ChaosEngine YAML or execute the following command:
kubectl patch chaosengine <chaosengine-name> -n <namespace> --type merge --patch '{"spec":{"engineState":"active"}}'
Check Chaos Experiment Result
Check whether the cassandra statefulset is resilient to the pod failure, once the experiment (job) is completed. The ChaosResult resource name is derived like this:
<ChaosEngine-Name>-<ChaosExperiment-Name>
.kubectl describe chaosresult cassandra-chaos-cassandra-pod-delete -n <cassandra-namespace>
Cassandra Pod Failure Demo
- It will be added soon.