middleware/kubernetes: autopath in sub package (#848)

Put the autopath stuff in a separate sub package. Tests are still
included in the main kubernetes directory.

Next steps (after this is merged), is pulling the autopath handling
into the subpackage and fixing the tests.

middleware/kubernetes/kubernetes.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/coredns/coredns/middleware"
 	"github.com/coredns/coredns/middleware/etcd/msg"
+	"github.com/coredns/coredns/middleware/kubernetes/autopath"
 	"github.com/coredns/coredns/middleware/pkg/dnsutil"
 	dnsstrings "github.com/coredns/coredns/middleware/pkg/strings"
 	"github.com/coredns/coredns/middleware/proxy"
@@ -45,17 +46,9 @@ type Kubernetes struct {
 	PodMode       string
 	ReverseCidrs  []net.IPNet
 	Fallthrough   bool
-	AutoPath
-	interfaceAddrsFunc func() net.IP
-}
 
-// AutoPath enables server side search path lookups for pods
-type AutoPath struct {
-	Enabled        bool
-	NDots          int
-	ResolvConfFile string
-	HostSearchPath []string
-	OnNXDOMAIN     int
+	autoPath           *autopath.AutoPath
+	interfaceAddrsFunc func() net.IP
 }
 
 const (
@@ -259,7 +252,7 @@ func (k *Kubernetes) InitKubeCache() (err error) {
 	}
 
 	opts := dnsControlOpts{
-		initPodCache: (k.PodMode == PodModeVerified || k.AutoPath.Enabled),
+		initPodCache: (k.PodMode == PodModeVerified || (k.autoPath != nil)),
 	}
 	k.APIConn = newdnsController(kubeClient, k.ResyncPeriod, k.Selector, opts)
 
@@ -468,7 +461,7 @@ func (k *Kubernetes) getRecordsForK8sItems(services []service, pods []pod, r rec
 }
 
 func (k *Kubernetes) findPodWithIP(ip string) (p *api.Pod) {
-	if !k.AutoPath.Enabled {
+	if k.autoPath == nil {
 		return nil
 	}
 	objList := k.APIConn.PodIndex(ip)