Pod Network Duplication Experiment Details
Experiment Metadata
Type | Description | Tested K8s Platform |
---|---|---|
Generic | Inject Packet Duplication Into Application Pod | GKE, Packet(Kubeadm), EKS, Minikube > v1.6.0, 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
pod-network-duplication
experiment resource is available in the cluster by executingkubectl get chaosexperiments
in the desired namespace. If not, install from hereNOTE: 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
apiVersion: v1
kind: ServiceAccount
metadata:
name: pod-network-duplication-sa
namespace: default
labels:
name: pod-network-duplication-sa
app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
name: pod-network-duplication-sa
namespace: default
labels:
name: pod-network-duplication-sa
app.kubernetes.io/part-of: litmus
rules:
- apiGroups: ["","litmuschaos.io","batch"]
resources: ["pods","jobs","events","pods/log","chaosengines","chaosexperiments","chaosresults"]
verbs: ["create","list","get","patch","update","delete","deletecollection"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: pod-network-duplication-sa
namespace: default
labels:
name: pod-network-duplication-sa
app.kubernetes.io/part-of: litmus
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
Supported Experiment Tunables
Variables | Description | Specify In ChaosEngine | Notes |
---|---|---|---|
NETWORK_INTERFACE | Name of ethernet interface considered for shaping traffic | Mandatory | |
TARGET_CONTAINER | Name of container which is subjected to network latency | Optional | By default it will take the first container of the target application pod |
NETWORK_PACKET_DUPLICATION_PERCENTAGE | The packet duplication in percentage | Optional | Default to 100 percentage |
TOTAL_CHAOS_DURATION | The time duration for chaos insertion (seconds) | Optional | Default (60s) |
PODS_AFFECTED_PERC | The Percentage of total pods to target | Optional | Defaults to 0% (corresponds to 1 replica) |
CONTAINER_RUNTIME | container runtime interface for the cluster | Optional | Defaults to docker, supported values: docker, containerd, crio |
SOCKET_PATH | Path of the containerd/crio socket file | Optional | Defaults to `/run/containerd/containerd.sock` |
TARGET_POD | Name of the application pod subjected to pod network duplication chaos | Optional | If not provided it will select from the appLabel provided | If not provided it will select from the app label provided |
TARGET_IPs | IP addresses of the services or pods, the accessibility to which, is impacted | Optional | if not provided, it will induce network chaos for all ips/destinations |
TARGET_HOSTS | DNS Names/FQDN names of the services, the accessibility to which, is impacted | Optional | if not provided, it will induce network chaos for all ips/destinations or TARGET_IPs if already defined |
LIB | The chaos lib used to inject the chaos | Optional | Defaults to litmus, only litmus supported |
TC_IMAGE | Image used for traffic control in linux | Optional | default value is `gaiadocker/iproute2` |
LIB_IMAGE | Image used to run the netem command | Optional | Defaults to `litmuschaos/go-runner:latest` |
RAMP_TIME | Period to wait before and after injection of chaos in sec | Optional | |
SEQUENCE | It defines sequence of chaos execution for multiple target pods | Optional | Default value: parallel. Supported: serial, parallel |
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
# 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: 'litmuschaos/go-runner:latest'
#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: ''
# 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 and crio 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 network latency by setting up a ping on the affected pod from the cluster nodes
ping <pod_ip_address>
Abort/Restart the Chaos Experiment
To stop the pod-network-duplication 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 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.