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Version: release-0.7

Simulate DNS faults

DNSChaos is used to simulate wrong DNS responses. For example, DNSChaos can return an error or return a random IP address when receiving a DNS request.

Deploy Chaos DNS server

Check whether Chaos DNS Server is deployed by running the following command:

kubectl get pods -n chaos-mesh -l app.kubernetes.io/component=chaos-dns-server

Make sure that the Pod status is Running.

Notes

  1. Currently, DNSChaos only supports record types A and AAAA.

  2. The Chaos DNS service runs CoreDNS with the k8s_dns_chaos plugin. If the CoreDNS service in your Kubernetes cluster contains some special configurations, you can edit configMap dns-server-config to make the configuration of the chaos DNS service consistent with that of the K8s CoreDNS service using the following command:

    kubectl edit configmap dns-server-config -n chaos-mesh

Simulate fault injections by kbcli

DNS faults can be simulated as random and error. You can select one type for DNS fault injection.

--pattern selects a domain template that matches faults and it is required. Placeholder ? and wildcard * are supported.

DNS random

Run the command below to inject DNS faults into all Pods in the default namespace, which means a random IP address will be returned when a DNS request is sent to the specified domains.

kbcli fault network dns random --patterns=google.com --duration=1m

DNS error

Run the command below to inject DNS faults into all Pods in the default namespace, which means an error will be returned when a DNS request is sent to the specified domains.

kbcli fault network dns error --patterns=google.com --duration=1m

Simulate fault injections by YAML file

This section introduces the YAML configuration file examples. You can view the YAML file by adding --dry-run at the end of the above kbcli commands. Meanwhile, you can also refer to the Chaos Mesh official docs for details.

DNS-random example

  1. Write the experiment configuration to the dns-random.yaml file.

    In the following example, Chaos Mesh injects DNS faults into all Pods in the default namespace, which means an IP address will be returned when a DNS request is sent to the specified domains.

    apiVersion: chaos-mesh.org/v1alpha1
    kind: DNSChaos
    metadata:
    creationTimestamp: null
    generateName: dns-chaos-
    namespace: default
    spec:
    action: random
    duration: 1m
    mode: all
    patterns:
    - google.com
    selector:
    namespaces:
    - default
  2. Run kubectl to start an experiment.

    kubectl apply -f ./dns-random.yaml

DNS-error example

  1. Write the experiment configuration to the dns-error.yaml file.

    In the following example, Chaos Mesh injects DNS faults into all Pods in the default namespace, which means an error will be returned when a DNS request is sent to the specified domains.

    apiVersion: chaos-mesh.org/v1alpha1
    kind: DNSChaos
    metadata:
    creationTimestamp: null
    generateName: dns-chaos-
    namespace: default
    spec:
    action: error
    duration: 1m
    mode: all
    patterns:
    - google.com
    selector:
    namespaces:
    - default
  2. Run kubectl to start an experiment.

    kubectl apply -f ./network-partition.yaml

Field description

ParameterTypeDescriptionDefault valueRequiredExample
actionstringDefines the behavior of DNS fault. Optional values: random or error. When the value is random, DNS service returns a random IP address; when the value is error, DNS service returns an error.NoneYesrandom or error
patternsString arraySelects a domain template that matches faults. Placeholder ? and wildcard * are supported.[]Nogoogle.com, chaos-mesh.org, github.com
modestringSpecifies the mode of the experiment. The mode options include one (selecting a random Pod), all (selecting all eligible Pods), fixed (selecting a specified number of eligible Pods), fixed-percent (selecting a specified percentage of Pods from the eligible Pods), and random-max-percent (selecting the maximum percentage of Pods from the eligible Pods).NoneYesone
valuestringProvides parameters for the mode configuration, depending on mode. For example, when mode is set to fixed-percent, value specifies the percentage of Pods.NoneNo1
selectorstructSpecifies the target Pod.NoneYes