Pod Network Latency Experiment Details
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 kubectlget chaosexperiments
in the desired namespace. . If not, install from here
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: 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
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_LATENCY | The latency/delay in milliseconds | Optional | Default (60000ms) |
TOTAL_CHAOS_DURATION | The time duration for chaos insertion (seconds) | Optional | Default (60000ms) |
LIB | The chaos lib used to inject the chaos | Optional | only `pumba` supported currently |
LIB_IMAGE | The pumba image used to run the kill command | Optional | Defaults to `gaiaadm/pumba:0.6.5` |
RAMP_TIME | Period to wait before and after injection of chaos in sec | Optional | |
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. | Ensure that the overall length of the chaosresult CR is still < 64 characters |
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 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.