kubepods

README

kubepods

Name

kubepods - create records for Kubernetes Pods.

Description

kubepods synthesizes A, AAAA, and PTR records for Pod addresses.

By default, this plugin requires ...

• The kubeapi plugin to make a connection to the Kubernetes API.
• CoreDNS's Service Account has list/watch permission to the Pods API.

This plugin can only be used once per Server Block.

Syntax

kubepods [ZONES...] {
    names MODE
    ttl TTL
    fallthrough [ZONES...]
}

• names MODE sets the record naming scheme to MODE. The following modes are available:
  • name - Default. Use the Pod's name and namespace. e.g. pod1.default.pod.cluster.local.
  • ip - Use the Pod's IP addresses and namespace. e.g. 1-2-3-4.default.pod.cluster.local.
  • name-and-ip - Use both modes name and ip, as above.
  • echo-ip - Like ip, but do not validate the Pod's existence and just echo the IP in the query to the response. Included only for backward compatibility, this implements the deprecated and insecure Pod records specification from Kubernetes DNS-Based Service Discovery. In this mode PTR records cannot be synthesized. This mode is considered insecure because it does not validate the existence of a Pod matching the IP. No connection to the API is required in this mode.
• ttl allows you to set a custom TTL for responses. The default is 5 seconds. The minimum TTL allowed is 0 seconds, and the maximum is capped at 3600 seconds. Setting TTL to 0 will prevent records from being cached. All endpoint queries and headless service queries will result in an NXDOMAIN.
• fallthrough [ZONES...] If a query for a record in the zones for which the plugin is authoritative results in NXDOMAIN, normally that is what the response will be. However, if you specify this option, the query will instead be passed on down the plugin chain, which can include another plugin to handle the query. If [ZONES...] is omitted, then fallthrough happens for all zones for which the plugin is authoritative. If specific zones are listed (for example in-addr.arpa and ip6.arpa), then only queries for those zones will be subject to fallthrough.

External Plugin

To use this plugin, compile CoreDNS with this plugin added to the plugin.cfg. It should be positioned before the kubernetes plugin if kubepods is using the same zone or a superzone of kubernetes. This plugin also requires the kubeapi plugin, which should be added to the end of plugin.cfg.

Metadata

The kubepods plugin will publish the following metadata if the metadata plugin is also enabled:

• kubepods/client-namespace: the client pod's namespace
• kubepods/client-pod-name: the client pod's name
• kubepods/client-pod-annotation-X: the client pod's annotations, where X is the annotation name

This metadata is not available in echo-ip mode.

Ready

This plugin reports that it is ready to the ready plugin once it has received the complete list of Pods from the Kubernetes API.

Examples

Use Pods' names and IP addresses to answer forward and reverse lookups in the zone pod.cluster.local.. Fallthrough to the next plugin for reverse lookups that don't match any Pod addresses.

kubeapi
kubepods pod.cluster.local in-addr.arpa ip6.arpa {
  fallthrough in-addr.arpa ip6.arpa
}

Documentation

Index

• type KubePods
  • func New(zones []string) *KubePods
  • func (k *KubePods) AutoPath(state request.Request) []string
  • func (k *KubePods) Metadata(ctx context.Context, state request.Request) context.Context
  • func (k *KubePods) Name() string
  • func (k *KubePods) Ready() bool
  • func (k *KubePods) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

Types

type KubePods

type KubePods struct {
	Next  plugin.Handler
	Zones []string

	Fall fall.F
	// contains filtered or unexported fields
}

KubePods is a plugin that creates records for a Kubernetes cluster's Pods.

func New

func New(zones []string) *KubePods

New returns a initialized KubePods.

func (*KubePods) AutoPath

func (k *KubePods) AutoPath(state request.Request) []string

AutoPath implements AutoPather

func (*KubePods) Metadata

func (k *KubePods) Metadata(ctx context.Context, state request.Request) context.Context

Metadata implements the metadata.Provider interface.

func (*KubePods) Name

func (k *KubePods) Name() string

Name implements the Handler interface.

func (*KubePods) Ready

func (k *KubePods) Ready() bool

Ready implements the ready.Readiness interface.

func (*KubePods) ServeDNS

func (k *KubePods) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the plugin.Handler interface.