k8s_dns_chaos

Description

This plugin implements the Kubernetes DNS-Based Service Discovery Specification.

CoreDNS running with the k8s_dns_chaos plugin can be used to do chaos tests on DNS.

This plugin can only be used once per Server Block.

Syntax

k8s_dns_chaos [ZONES...]

The k8s_dns_chaos supports all options in plugin kubernetes, besides, it also supports other configuration items for chaos.

kubernetes [ZONES...] {
    endpoint URL
    tls CERT KEY CACERT
    kubeconfig KUBECONFIG CONTEXT
    namespaces NAMESPACE...
    labels EXPRESSION
    pods POD-MODE
    endpoint_pod_names
    ttl TTL
    noendpoints
    transfer to ADDRESS...
    fallthrough [ZONES...]
    ignore empty_service

    chaos ACTION SCOPE [PODS...]
    grpcport PORT
}

Only [ZONES...], chaos and grpcport is different with plugin with kubernetes:

• [ZONES...] defines which zones of the host will be treated as internal hosts in the Kubernetes cluster.

• chaos ACTION SCOPE [PODS…] set the behavior and scope of chaos.

  Valid value for Action:

  • random: return random IP for DNS request.
  • error: return error for DNS request.

  Valid value for SCOPE:

  • inner: chaos only works on the inner host of the Kubernetes cluster.
  • outer: chaos only works on the outer host of the Kubernetes cluster.
  • all: chaos works on all the hosts.

  [PODS…] defines which Pods will take effect, the format is Namespace.PodName.

• grpcport PORT sets the port of GRPC service, which is used for the hot update of the chaos rules. The default value is 9288. The interface of the GRPC service is defined in dns.proto.

Examples

All DNS requests in Pod busybox.busybox-0 will get error:

    k8s_dns_chaos cluster.local in-addr.arpa ip6.arpa {
        pods insecure
        fallthrough in-addr.arpa ip6.arpa
        ttl 30
        chaos error all busybox.busybox-0
    }

The shell command below will execute failed:

    kubectl exec busybox-0 -it -n busybox -- ping -c 1 google.com
    ping: bad address 'google.com'