support for zone transfer for kubernetes (#1259)

* plugin/kubernetes: axfr

Hook up dynamic SOA serial by setting ResourceEventHandlerFuncs in
dnsController.

Add prototype of returns msg.Services via the Transfer function. Leave
expanding this to RRs out of scope for a bit.

* plugin/kubernetes: axfr

Respond to AXFR queries

* Fixing race condition

* Fixing instantiation of dnstest writer

* Updates from review

1 files changed, 10 insertions, 0 deletions

diff --git a/plugin/kubernetes/setup.go b/plugin/kubernetes/setup.go
index e8fc484bf..f79724dee 100644
--- a/plugin/kubernetes/setup.go
+++ b/plugin/kubernetes/setup.go
@@ -10,6 +10,7 @@ import (
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/pkg/dnsutil"
+	"github.com/coredns/coredns/plugin/pkg/parse"
 	"github.com/coredns/coredns/plugin/proxy"
 
 	"github.com/mholt/caddy"
@@ -197,6 +198,15 @@ func kubernetesParse(c *caddy.Controller) (*Kubernetes, dnsControlOpts, error) {
 					return nil, opts, c.Errf("ttl must be in range [5, 3600]: %d", t)
 				}
 				k8s.ttl = uint32(t)
+			case "transfer":
+				tos, froms, err := parse.Transfer(c, false)
+				if err != nil {
+					return nil, opts, err
+				}
+				if len(froms) != 0 {
+					return nil, opts, c.Errf("transfer from is not supported with this plugin")
+				}
+				k8s.TransferTo = tos
 			default:
 				return nil, opts, c.Errf("unknown property '%s'", c.Val())
 			}