kubenodes

Description

kubenodes watches the Kubernetes API and synthesizes A, AAAA, and PTR records for Node addresses.

This plugin requires …

• the kubeapi plugin to create a connection to the Kubernetes API. (http://github.com/coredns/kubeapi)
• list/watch permission to the Nodes API.

This plugin can only be used once per Server Block.

Syntax

kubenodes [ZONES...] {
    external
    ttl TTL
    fallthrough [ZONES...]
}

• external will build records using Nodes' external addresses. If omitted, kubenodes will build records using Nodes' internal addresses.
• 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 kubenode 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.

Ready

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

Examples

Use Nodes' internal addresses to answer forward and reverse lookups in the zone node.cluster.local.. Fallthrough to the next plugin for reverse lookups that don’t match any Nodes' internal IP addresses.

kubeapi
kubenodes node.cluster.local in-addr.arpa ip6.arpa {
  fallthrough in-addr.arpa ip6.arpa
}

Use Nodes' external addresses to answer forward and reverse lookups in the zone example.. Fallthrough to the next plugin for reverse lookups that don’t match any Nodes' external IP addresses.

kubeapi
kubenodes example in-addr.arpa ip6.arpa {
  external
  fallthrough in-addr.arpa ip6.arpa
}