litmus-docs/pod-network-latency.md at e67110a933930d584fb9b3befecb9db3e267ae4c

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id	title	sidebar_label	original_id
version-1.6.0-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), 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-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 [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/generic/pod-network-latency/rbac.yaml yaml) ```yaml

apiVersion: v1 kind: ServiceAccount metadata: name: pod-network-latency-sa namespace: default labels: name: pod-network-latency-sa

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

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

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

kind: ServiceAccount name: pod-network-latency-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> Type </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> Mandatory </td>
    <td> </td>
  </tr>
  <tr>
    <td> NETWORK_LATENCY </td>
    <td> The latency/delay in milliseconds </td>
    <td> Optional </td>
    <td> Default (60000ms) </td>
  </tr>
  <tr>
    <td> TOTAL_CHAOS_DURATION </td>
    <td> The time duration for chaos insertion (seconds) </td>
    <td> Optional </td>
    <td> Default (60000ms) </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> Ensure that the overall length of the chaosresult CR is still < 64 characters </td>
    <td> </td>
  </tr>

</table>

#### Sample ChaosEngine Manifest

[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/generic/pod-network-latency/engine.yaml yaml)
```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-latency-sa
  experiments:
    - name: pod-network-latency
      spec:
        components:
          env:
            #Container name where chaos has to be injected
            - name: TARGET_CONTAINER
              value: 'nginx' 

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

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

            - name: NETWORK_LATENCY
              value: '60000'

            - name: TOTAL_CHAOS_DURATION
              value: '60' # in seconds

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 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.

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