Add ability to resolve service FQDNs from host during 'minikube tunnel' (MacOS only for now)

Author: ceason

pkg/minikube/tunnel/cluster_inspector.go

@@ -18,6 +18,7 @@ package tunnel
 
 import (
 	"fmt"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"net"
 
 	"github.com/docker/machine/libmachine"
@@ -93,9 +94,14 @@ func getRoute(host *host.Host, clusterConfig config.Config) (*Route, error) {
 	if ip == nil {
 		return nil, fmt.Errorf("invalid IP for host %s", hostDriverIP)
 	}
-
+	dnsIp, err := constants.GetDNSIP(ipNet.String())
+	if err != nil {
+		return nil, err
+	}
 	return &Route{
-		Gateway:  ip,
-		DestCIDR: ipNet,
+		Gateway:       ip,
+		DestCIDR:      ipNet,
+		ClusterDomain: clusterConfig.KubernetesConfig.DNSDomain,
+		ClusterDNSIP:  dnsIp,
 	}, nil
 }

pkg/minikube/tunnel/route_darwin.go

@@ -18,7 +18,9 @@ package tunnel
 
 import (
 	"fmt"
+	"io/ioutil"
 	"net"
+	"os"
 	"os/exec"
 	"regexp"
 	"strings"
@@ -34,6 +36,9 @@ func (router *osRouter) EnsureRouteIsAdded(route *Route) error {
 	if exists {
 		return nil
 	}
+	if err := writeResolverFile(route); err != nil {
+		return fmt.Errorf("could not write /etc/resolver/{cluster_domain} file: %s", err)
+	}
 
 	serviceCIDR := route.DestCIDR.String()
 	gatewayIP := route.Gateway.String()
@@ -162,5 +167,37 @@ func (router *osRouter) Cleanup(route *Route) error {
 	if !re.MatchString(message) {
 		return fmt.Errorf("error deleting route: %s, %d", message, len(strings.Split(message, "\n")))
 	}
+	// idempotent removal of cluster domain dns
+	resolverFile := fmt.Sprintf("/etc/resolver/%s", route.ClusterDomain)
+	command = exec.Command("sudo", "rm", "-f", resolverFile)
+	if err := command.Run(); err != nil {
+		return fmt.Errorf("could not remove %s: %s", resolverFile, err)
+	}
+	return nil
+}
+
+func writeResolverFile(route *Route) error {
+	resolverFile := "/etc/resolver/" + route.ClusterDomain
+	content := fmt.Sprintf("nameserver %s\nsearch_order 1\n", route.ClusterDNSIP)
+	// write resolver content into tmpFile, then copy it to /etc/resolver/clusterDomain
+	tmpFile, err := ioutil.TempFile("", "minikube-tunnel-resolver-")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(tmpFile.Name())
+	if _, err = tmpFile.WriteString(content); err != nil {
+		return err
+	}
+	if err = tmpFile.Close(); err != nil {
+		return err
+	}
+	command := exec.Command("sudo", "mkdir", "-p", "/etc/resolver")
+	if err := command.Run(); err != nil {
+		return err
+	}
+	command = exec.Command("sudo", "cp", "-f", tmpFile.Name(), resolverFile)
+	if err := command.Run(); err != nil {
+		return err
+	}
 	return nil
 }

pkg/minikube/tunnel/types.go

@@ -58,8 +58,10 @@ func (t *Status) String() string {
 }
 
 type Route struct {
-	Gateway  net.IP
-	DestCIDR *net.IPNet
+	Gateway       net.IP
+	DestCIDR      *net.IPNet
+	ClusterDomain string
+	ClusterDNSIP  net.IP
 }
 
 func (r *Route) String() string {