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

id	title	sidebar_label	original_id
pod-network-latency	Pod Network Latency Experiment Details	Pod Network Latency	pod-network-latency

---

Experiment Metadata

Type	Description	Tested K8s Platform
Generic	Inject Network Latency 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-latency experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. . If not, install from here

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.
• Causes flaky access to application replica by injecting network delay using pumba.
• Injects latency on the specified container by starting a traffic control (tc) process with netem rules to add egress delays
• Latency is injected via pumba library with command pumba netem delay by passing the relevant network interface, latency, 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
TOTAL_CHAOS_DURATION	The time duration for chaos insertion in milliseconds	Optional	Default (60000ms)
NETWORK_LATENCY	The latency/delay in milliseconds	Optional	Default (60000ms)
LIB	The chaos lib used to inject the chaos eg. Pumba	Optional
CHAOSENGINE	ChaosEngine CR name associated with the experiment instance	Optional
CHAOS_SERVICE_ACCOUNT	Service account used by the pumba daemonset Optional	Optional

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-latency
      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
          - name: LIB_IMAGE
            value: gaiaadm/pumba:0.6.5
          - name: NETWORK_LATENCY
            value: "2000"
          - name: TOTAL_CHAOS_DURATION
            value: "60000"
          - name: LIB
            value: pumba

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 network latency by setting up a ping on the affected pod from the cluster nodes

  ping <pod_ip_address>

Check Chaos Experiment Result

• Check whether the application is resilient to the Pod Network Latency, 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 Latency Demo

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