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COREDNS-K8S_EXTERNAL(7)		CoreDNS	Plugins	       COREDNS-K8S_EXTERNAL(7)

NAME
       k8s_external - resolves load balancer and external IPs from outside Ku-
       bernetes	clusters.

DESCRIPTION
       This  plugin  allows  an	additional zone	to resolve the external	IP ad-
       dress(es) of a Kubernetes service. This plugin is only  useful  if  the
       kubernetes plugin is also loaded.

       The plugin uses an external zone	to resolve in-cluster IP addresses. It
       only  handles queries for A, AAAA and SRV records; all others result in
       NODATA responses. To make it a proper DNS zone, it handles SOA  and  NS
       queries for the apex of the zone.

       By  default the apex of the zone	will look like the following (assuming
       the zone	used is	example.org):

	      example.org.    5	IN    SOA ns1.dns.example.org. hostmaster.example.org. (
			      12345	 ; serial
			      14400	 ; refresh (4 hours)
			      3600	 ; retry (1 hour)
			      604800	 ; expire (1 week)
			      5		 ; minimum (4 hours)
			      )
	      example.org	 5 IN	 NS ns1.dns.example.org.

	      ns1.dns.example.org.  5 IN  A    ....
	      ns1.dns.example.org.  5 IN  AAAA ....

       Note that we use	the dns	subdomain for the records DNS needs  (see  the
       apex  directive).  Also	note the SOA's serial number is	static.	The IP
       addresses of the	nameserver records are those of	the CoreDNS service.

       The k8s_external	plugin handles the subdomain dns and the apex  of  the
       zone  itself;  all other	queries	are resolved to	addresses in the clus-
       ter.

SYNTAX
	      k8s_external [ZONE...]

       •   ZONES zones k8s_external should be authoritative for.

       If you want to change the apex domain or	use a different	 TTL  for  the
       returned	records	you can	use this extended syntax.

	      k8s_external [ZONE...] {
		  apex APEX
		  ttl TTL
	      }

       •   APEX	 is  the  name (DNS label) to use for the apex records;	it de-
	   faults to dns.

       •   ttl allows you to set a custom TTL for responses. The default is  5
	   (seconds).

EXAMPLES
       Enable  names  under  example.org  to be	resolved to in-cluster DNS ad-
       dresses.

	      .	{
		 kubernetes cluster.local
		 k8s_external example.org
	      }

       With the	Corefile above,	the following Service will get an A record for
       test.default.example.org	with the IP address 192.168.200.123.

	      apiVersion: v1
	      kind: Service
	      metadata:
	       name: test
	       namespace: default
	      spec:
	       clusterIP: None
	       externalIPs:
	       - 192.168.200.123
	       type: ClusterIP

       For   some    background	   see	  resolve    external	 IP    address
       <https://github.com/kubernetes/dns/issues/242>.	And A records for ser-
       vices  with  Load  Balancer  IP <https://github.com/coredns/coredns/is-
       sues/1851>.

       PTR queries for the reverse zone	is not supported.

CoreDNS				  March	2021	       COREDNS-K8S_EXTERNAL(7)

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