litmus-docs/Versioned_docs_and_sidebars/versioned_docs/version-1.6.0/pod-network-duplication.md

id	title	sidebar_label	original_id
version-1.6.0-pod-network-duplication	Pod Network Duplication Experiment Details	Pod Network Duplication	pod-network-duplication

## Experiment Metadata

Type	Description	Tested K8s Platform
Generic	Inject Packet Duplication Into Application Pod	GKE, Packet(Kubeadm), EKS, Minikube, AKS > 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-duplication 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 - pod-network-duplication injects chaos to disrupt network connectivity to kubernetes pods. - The application pod should be healthy once chaos is stopped. Service-requests should be served despite chaos. - Causes Injection of network duplication on the specified container by starting a traffic control (tc) process with netem rules to add egress delays. It Can test the application's resilience to duplicate 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 [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/generic/pod-network-duplication/rbac.yaml yaml) ```yaml apiVersion: v1 kind: ServiceAccount metadata: name: pod-network-duplication-sa namespace: default labels: name: pod-network-duplication-sa

apiVersion: rbac.authorization.k8s.io/v1beta1 kind: Role metadata: name: pod-network-duplication-sa namespace: default labels: name: pod-network-duplication-sa rules:

• apiGroups: ["","litmuschaos.io","batch"] resources: ["pods","jobs","events","pods/log","chaosengines","chaosexperiments","chaosresults"] verbs: ["create","list","get","patch","update","delete"]

---

apiVersion: rbac.authorization.k8s.io/v1beta1 kind: RoleBinding metadata: name: pod-network-duplication-sa namespace: default labels: name: pod-network-duplication-sa roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: pod-network-duplication-sa subjects:

• kind: ServiceAccount name: pod-network-duplication-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](chaosengine-concepts.md)

#### Supported Experiment Tunables

<table>
  <tr>
    <th> Variables </th>
    <th> Description  </th>
    <th> Specify In ChaosEngine </th>
    <th> Notes </th>
  </tr>
  <tr>
    <td> NETWORK_INTERFACE </td>
    <td> Name of ethernet interface considered for shaping traffic  </td>
    <td> Mandatory </td>
    <td> </td>
  </tr>
  <tr>
    <td> TARGET_CONTAINER  </td>
    <td> Name of container which is subjected to network latency </td>
    <td> Optional </td>
     <td> By default it will take the first container of the target application pod </td>
  </tr>
  <tr>
    <td> NETWORK_PACKET_DUPLICATION_PERCENTAGE </td>
    <td> The packet duplication in percentage </td>
    <td> Optional </td>
    <td> Default to 100 percentage </td>
  </tr>
  <tr>
    <td> TOTAL_CHAOS_DURATION </td>
    <td> The time duration for chaos insertion (seconds) </td>
    <td> Optional </td>
    <td> Default (60s) </td>
  </tr>
  <tr>
    <td> LIB </td>
    <td> The chaos lib used to inject the chaos </td>
    <td> Optional  </td>
    <td> only `pumba` supported currently </td>
  </tr>
  <tr>
    <td> LIB_IMAGE  </td>
    <td> The pumba image used to run the kill command </td>
    <td> Optional  </td>
    <td> Defaults to `gaiaadm/pumba:0.6.5` </td>
  </tr>
  <tr>
    <td> RAMP_TIME </td>
    <td> Period to wait before and after injection of chaos in sec </td>
    <td> Optional  </td>
    <td> </td>
  </tr>
  <tr>
    <td> INSTANCE_ID </td>
    <td> 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.</td>
    <td> Optional  </td>
    <td> Ensure that the overall length of the chaosresult CR is still < 64 characters </td>
  </tr>

</table>

#### Sample ChaosEngine Manifest

[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/generic/pod-network-duplication/engine.yaml yaml)
```yaml
# chaosengine.yaml
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: nginx-network-chaos
  namespace: default
spec:
  # It can be delete/retain
  jobCleanUpPolicy: 'delete'
  # It can be true/false
  annotationCheck: 'true'
  # It can be active/stop
  engineState: 'active'
  #ex. values: ns1:name=percona,ns2:run=nginx 
  auxiliaryAppInfo: ''
  monitoring: false
  appinfo: 
    appns: 'default'
    # FYI, To see app label, apply kubectl get pods --show-labels
    applabel: 'app=nginx'
    appkind: 'deployment'
  chaosServiceAccount: pod-network-duplication-sa 
  experiments:
    - name: pod-network-duplication
      spec:
        components:
          env:
            - name: TOTAL_CHAOS_DURATION
              value: '60' # in seconds

            - name: LIB_IMAGE
              value: 'gaiaadm/pumba:0.6.5'

            #Network interface inside target container
            - name: NETWORK_INTERFACE
              value: 'eth0'    

            - name: NETWORK_PACKET_DUPLICATION_PERCENTAGE
              value: '100'
            
            #If not provided it will take the first container of the target pod
            - name: TARGET_CONTAINER
              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 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 Duplication, 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 Duplication Demo

• A sample recording of this experiment execution will be provided very soon.