Pod CPU Hog Details
Experiment Metadata
Type | Description | Tested K8s Platform |
---|---|---|
Generic | Consume CPU resources on the application container | GKE, Packet(Kubeadm), Minikube |
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
pod-cpu-hog
experiment resource is available in the cluster by executingkubectl get chaosexperiments
in the desired namespace. If not, install from here - Cluster must run docker container runtime
Entry Criteria
- Application pods are healthy on the respective nodes before chaos injection
Exit Criteria
- Application pods are healthy on the respective nodes post chaos injection
Details
- This experiment consumes the CPU resources on the application container (upward of 80%) on specified number of cores
- It simulates conditions where app pods experience CPU spikes either due to expected/undesired processes thereby testing how the overall application stack behaves when this occurs.
Integrations
- Pod CPU can be effected using the chaos library:
litmus
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.
Sample Rbac Manifest
apiVersion: v1
kind: ServiceAccount
metadata:
name: nginx-sa
namespace: default
labels:
name: nginx-sa
---
# Source: openebs/templates/clusterrole.yaml
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
metadata:
name: nginx-sa
labels:
name: nginx-sa
rules:
- apiGroups: ["","litmuschaos.io","batch"]
resources: ["pods","jobs","chaosengines","chaosexperiments","chaosresults"]
verbs: ["create","list","get","patch","update","delete"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
name: nginx-sa
labels:
name: nginx-sa
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: nginx-sa
subjects:
- kind: ServiceAccount
name: nginx-sa
namespace: default
Prepare ChaosEngine
- Provide the application info in
spec.appinfo
- Provide the auxiliary applications info (ns & labels) in
spec.auxiliaryAppInfo
- Override the experiment tunables if desired
Supported Experiment Tunables
Variables | Description | Type | Notes | |
---|---|---|---|---|
TARGET_CONTAINER | Name of the container subjected to CPU stress | Mandatory | ||
CPU_CORES | Name of the container subjected to CPU stress | Optional | Defaults to 1 | |
TOTAL_CHAOS_DURATION | The time duration for chaos insertion (seconds) | Optional | Defaults to 60s | |
LIB_IMAGE | The image used by the litmus (only supported) lib | Optional | Defaults to `litmuschaos/app-cpu-stress:latest` |
Sample ChaosEngine Manifest
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: nginx-chaos
namespace: default
spec:
# It can be app/infra
chaosType: 'app'
#ex. values: ns1:name=percona,ns2:run=nginx
auxiliaryAppInfo: ""
appinfo:
appns: default
applabel: 'app=nginx'
appkind: deployment
chaosServiceAccount: nginx-sa
monitoring: false
components:
runner:
image: "litmuschaos/chaos-executor:1.0.0"
type: "go"
# It can be delete/retain
jobCleanUpPolicy: delete
experiments:
- name: pod-cpu-hog
spec:
components:
- name: TARGET_CONTAINER
value: 'nginx'
#number of cpu cores to be consumed
#verify the resources the app has been launched with
- name: CPU_CORES
value: "1"
# in ms
- name: TOTAL_CHAOS_DURATION
value: "60000"
Create the ChaosEngine Resource
Create the ChaosEngine manifest prepared in the previous step to trigger the Chaos.
kubectl apply -f chaosengine.yml
Watch Chaos progress
Set up a watch on the applications interacting/dependent on the affected pods and verify whether they are running
watch kubectl get pods -n <application-namespace>
Check Chaos Experiment Result
Check whether the application stack is resilient to CPU spikes on the app replica, once the experiment (job) is completed. The ChaosResult resource name is derived like this:
<ChaosEngine-Name>-<ChaosExperiment-Name>
.kubectl describe chaosresult nginx-chaos-pod-cpu-hog -n <application-namespace>
Pod CPU Hog Experiment Demo
- A sample recording of this experiment execution is provided here.