litmus-docs/website/versioned_docs/version-1.8.0/container-kill.md

id	title	sidebar_label	original_id
container-kill	Container Kill Experiment Details	Container Kill	container-kill

---

Experiment Metadata

Type	Description	Tested K8s Platform
Generic	Kill one container in the application pod	GKE, Packet(Kubeadm), Minikube, EKS, AKS

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 container-kill experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. If not, install from here

Entry Criteria

• Application pods are healthy before chaos injection

Exit Criteria

• Application pods are healthy post chaos injection

Details

• litmus lib in docker runtime details
  • It can kill the container of multiple pods in parellel (can be tuned by PODS_AFFECTED_PERC env). It kill the container by sending SIGKILL termination signal to its docker socket (hence docker runtime is required)
  • Containers are killed using the kill command provided by pumba
  • Pumba is run as a pod on the application node. It have ability to kill the application containers multiple times. Which can be varied by TOTAL_CHAOS_DURATION and CHAOS_INTERVAL.
• litmus chaoslib in containerd and crio runtime codetails
  • It can kill the container of multiple pods in parellel (can be tuned by PODS_AFFECTED_PERC env).
  • Containers are killed using the crictl stop command.
  • container-kill is run as a pod on the application node. It have ability to kill the application containers multiple times. Which can be varied by TOTAL_CHAOS_DURATION and CHAOS_INTERVAL.
• Tests deployment sanity (replica availability & uninterrupted service) and recovery workflow of the application
• Good for testing recovery of pods having side-car containers

Integrations

• Container kill is achieved using the litmus chaos library
• The container runtime can be choose via setting CONTAINER_RUNTIME env. supported values: docker, containerd, crio
• The desired pumba and litmus image can be configured in the env variable LIB_IMAGE.

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: container-kill-sa
  namespace: default
  labels:
    name: container-kill-sa
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
metadata:
  name: container-kill-sa
  namespace: default
  labels:
    name: container-kill-sa
rules:
  - apiGroups: ["", "litmuschaos.io", "batch", "apps"]
    resources:
      [
        "pods",
        "jobs",
        "pods/exec",
        "pods/log",
        "events",
        "chaosengines",
        "chaosexperiments",
        "chaosresults",
      ]
    verbs:
      ["create", "list", "get", "patch", "update", "delete", "deletecollection"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
  name: container-kill-sa
  namespace: default
  labels:
    name: container-kill-sa
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: container-kill-sa
subjects:
  - kind: ServiceAccount
    name: container-kill-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
TARGET_CONTAINER	The container to be killed inside the pod	Mandatory	If the TARGET_CONTAINER is not provided it will delete the first container
CHAOS_INTERVAL	Time interval b/w two successive container kill (in sec)	Optional	If the CHAOS_INTERVAL is not provided it will take the default value of 10s
TOTAL_CHAOS_DURATION	The time duration for chaos injection (seconds)	Optional	Defaults to 20s
PODS_AFFECTED_PERC	The Percentage of total pods to target	Optional	Defaults to 0% (corresponds to 1 replica)
TARGET_POD	Name of the application pod subjected to container kill chaos	Optional	If not provided it will select from the app label provided
LIB_IMAGE	LIB Image used to kill the container	Optional	Defaults to `litmuschaos/go-runner:latest`
LIB	The category of lib use to inject chaos	Optional	Default value: litmus, only litmus supported
RAMP_TIME	Period to wait before injection of chaos in sec	Optional
SOCKET_PATH	Path of the containerd/crio socket file	Optional	Defaults to `/run/containerd/containerd.sock`
CONTAINER_RUNTIME	container runtime interface for the cluster	Optional	Defaults to docker, supported values: docker, containerd, crio
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: nginx-chaos
  namespace: default
spec:
  # It can be true/false
  annotationCheck: "true"
  # It can be active/stop
  engineState: "active"
  #ex. values: ns1:name=percona,ns2:run=nginx
  auxiliaryAppInfo: ""
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: container-kill-sa
  monitoring: false
  # It can be delete/retain
  jobCleanUpPolicy: "delete"
  experiments:
    - name: container-kill
      spec:
        components:
          env:
            # specify the name of the container to be killed
            - name: TARGET_CONTAINER
              value: "nginx"

            # provide the chaos interval
            - name: CHAOS_INTERVAL
              value: "10"

            # provide the total chaos duration
            - name: TOTAL_CHAOS_DURATION
              value: "20"

            # provide the name of container runtime
            # it supports docker, containerd, crio
            # default to docker
            - name: CONTAINER_RUNTIME
              value: "docker"

            # provide the socket file path
            # applicable only for containerd runtime
            - name: SOCKET_PATH
              value: "/run/containerd/containerd.sock"

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 restart count 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 application is resilient to the container kill, once the experiment (job) is completed. The ChaosResult resource name is derived like this: <ChaosEngine-Name>-<ChaosExperiment-Name>.

  kubectl describe chaosresult nginx-chaos-container-kill -n <application-namespace>

Application Container Kill Demo

• A sample recording of this experiment execution is provided here.