litmus-docs/website/versioned_docs/version-1.0.0/pod-network-corruption.md

id	title	sidebar_label	original_id
pod-network-corruption	Pod Network Corruption Experiment Details	Pod Network Corruption	pod-network-corruption

---

Experiment Metadata

Type	Description	Tested K8s Platform
Generic	Inject Network Packet Corruption Into Application Pod	GKE, Packet(Kubeadm), Minikube > v1.6.0

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-network-corruption experiment resource is available in the cluster by kubectl get chaosexperiments command. If not, install from here
• Cluster must run docker container runtime

NOTE: Experiment is supported only on Docker Runtime. Support for containerd/CRIO runtimes will be added in subsequent releases.

Entry Criteria

• Application pods are healthy before chaos injection

Exit Criteria

• Application pods are healthy post chaos injection

Details

• The application pod should be healthy once chaos is stopped. Service-requests should be served despite chaos.
• Injects packet corruption on the specified container by starting a traffic control (tc) process with netem rules to add egress packet corruption
• Corruption is injected via pumba library with command pumba netem corruption by passing the relevant network interface, packet-corruption-percentage, chaos duration and regex filter for container name
• Can test the application's resilience to lossy/flaky network

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
• Override the experiment tunables if desired

Supported Experiment Tunables

Variables	Description	Type	Notes
NETWORK_INTERFACE	Name of ethernet interface considered for shaping traffic	Mandatory
TARGET_CONTAINER	Name of container which is subjected to network latency	Mandatory
NETWORK_PACKET_CORRUPTION_PERCENTAGE	Packet corruption in percentage	Mandatory	Default (100)
LIB	The chaos lib used to inject the chaos eg. Pumba	Optional	only pumba supported currently
CHAOSENGINE	ChaosEngine CR name associated with the experiment instance	Optional
CHAOS_SERVICE_ACCOUNT	Service account used by the pumba daemonset Optional	Optional
TOTAL_CHAOS_DURATION	The time duration for chaos insertion in milliseconds	Optional	Default (60000ms)
LIB_IMAGE	The pumba image used to run the kill command	Optional	Defaults to gaiaadm/pumba:0.6.5

Sample ChaosEngine Manifest

apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: nginx-network-chaos
  namespace: default
spec:
  # It can be delete/retain
  jobCleanUpPolicy: delete
  # It can be app/infra
  chaosType: "app"
  #ex. values: ns1:name=percona,ns2:run=nginx
  auxiliaryAppInfo: ""
  monitoring: false
  components:
    runner:
      image: "litmuschaos/chaos-executor:1.0.0"
      type: "go"
  appinfo:
    appns: default
    # FYI, To see app label, apply kubectl get pods --show-labels
    applabel: "app=nginx"
    appkind: deployment
  chaosServiceAccount: nginx-sa
  experiments:
    - name: pod-network-corruption
      spec:
        components:
          - name: ANSIBLE_STDOUT_CALLBACK
            value: default
          - name: TARGET_CONTAINER
            #Container name where chaos has to be injected
            value: "nginx"
          - name: NETWORK_INTERFACE
            #Network interface inside target container
            value: eth0

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

• View impact of network packet corruption on the affected pod from the cluster nodes (alternate is to setup ping to a remote IP from inside the target pod)

  ping <pod_ip_address>

Check Chaos Experiment Result

• Check whether the application is resilient to the Pod Network Packet Corruption, once the experiment (job) is completed. The ChaosResult resource name is derived like this: <ChaosEngine-Name>-<ChaosExperiment-Name>.

  kubectl describe chaosresult <ChaosEngine-Name>-<ChaosExperiment-Name> -n <application-namespace>

Application Pod Network Packet Corruption Demo

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