Use forward plugin instead of proxy in the default configuration

cluster/addons/dns/coredns/coredns.yaml.base

@@ -70,7 +70,7 @@ data:
             fallthrough in-addr.arpa ip6.arpa
         }
         prometheus :9153
-        proxy . /etc/resolv.conf
+        forward . /etc/resolv.conf
         cache 30
         loop
         reload

cluster/addons/dns/coredns/coredns.yaml.in

@@ -70,7 +70,7 @@ data:
             fallthrough in-addr.arpa ip6.arpa
         }
         prometheus :9153
-        proxy . /etc/resolv.conf
+        forward . /etc/resolv.conf
         cache 30
         loop
         reload

cluster/addons/dns/coredns/coredns.yaml.sed

@@ -70,7 +70,7 @@ data:
             fallthrough in-addr.arpa ip6.arpa
         }
         prometheus :9153
-        proxy . /etc/resolv.conf
+        forward . /etc/resolv.conf
         cache 30
         loop
         reload

cmd/kubeadm/app/phases/addons/dns/dns.go

@@ -172,7 +172,7 @@ func coreDNSAddon(cfg *kubeadmapi.InitConfiguration, client clientset.Interface)
 		return err
 	}
 
-	stubDomain, err := translateStubDomainOfKubeDNSToProxyCoreDNS(kubeDNSStubDomain, kubeDNSConfigMap)
+	stubDomain, err := translateStubDomainOfKubeDNSToForwardCoreDNS(kubeDNSStubDomain, kubeDNSConfigMap)
 	if err != nil {
 		return err
 	}
@@ -294,9 +294,9 @@ func createDNSService(dnsService *v1.Service, serviceBytes []byte, client client
 	return nil
 }
 
-// translateStubDomainOfKubeDNSToProxyCoreDNS translates StubDomain Data in kube-dns ConfigMap
+// translateStubDomainOfKubeDNSToForwardCoreDNS translates StubDomain Data in kube-dns ConfigMap
 // in the form of Proxy for the CoreDNS Corefile.
-func translateStubDomainOfKubeDNSToProxyCoreDNS(dataField string, kubeDNSConfigMap *v1.ConfigMap) (string, error) {
+func translateStubDomainOfKubeDNSToForwardCoreDNS(dataField string, kubeDNSConfigMap *v1.ConfigMap) (string, error) {
 	if kubeDNSConfigMap == nil {
 		return "", nil
 	}
@@ -316,7 +316,7 @@ func translateStubDomainOfKubeDNSToProxyCoreDNS(dataField string, kubeDNSConfigM
 				{"errors"},
 				{"cache", "30"},
 				{"loop"},
-				append([]string{"proxy", "."}, proxyIP...),
+				append([]string{"forward", "."}, proxyIP...),
 			}
 			proxyStanza = append(proxyStanza, pStanza)
 		}

cmd/kubeadm/app/phases/addons/dns/dns_test.go

@@ -206,28 +206,28 @@ func TestTranslateStubDomainKubeDNSToCoreDNS(t *testing.T) {
        errors
        cache 30
        loop
-       proxy . 1.2.3.4:5300 3.3.3.3
+       forward . 1.2.3.4:5300 3.3.3.3
     }
     
     my.cluster.local:53 {
        errors
        cache 30
        loop
-       proxy . 2.3.4.5
+       forward . 2.3.4.5
     }`,
 			expectTwo: `
     my.cluster.local:53 {
        errors
        cache 30
        loop
-       proxy . 2.3.4.5
+       forward . 2.3.4.5
     }
     
     foo.com:53 {
        errors
        cache 30
        loop
-       proxy . 1.2.3.4:5300 3.3.3.3
+       forward . 1.2.3.4:5300 3.3.3.3
     }`,
 		},
 		{
@@ -257,28 +257,28 @@ func TestTranslateStubDomainKubeDNSToCoreDNS(t *testing.T) {
        errors
        cache 30
        loop
-       proxy . 1.2.3.4:5300
+       forward . 1.2.3.4:5300
     }
     
     my.cluster.local:53 {
        errors
        cache 30
        loop
-       proxy . 2.3.4.5
+       forward . 2.3.4.5
     }`,
 			expectTwo: `
     my.cluster.local:53 {
        errors
        cache 30
        loop
-       proxy . 2.3.4.5
+       forward . 2.3.4.5
     }
     
     foo.com:53 {
        errors
        cache 30
        loop
-       proxy . 1.2.3.4:5300
+       forward . 1.2.3.4:5300
     }`,
 		},
 		{
@@ -296,7 +296,7 @@ func TestTranslateStubDomainKubeDNSToCoreDNS(t *testing.T) {
 		},
 	}
 	for _, testCase := range testCases {
-		out, err := translateStubDomainOfKubeDNSToProxyCoreDNS(kubeDNSStubDomain, testCase.configMap)
+		out, err := translateStubDomainOfKubeDNSToForwardCoreDNS(kubeDNSStubDomain, testCase.configMap)
 		if err != nil {
 			t.Errorf("unexpected error: %v", err)
 		}

cmd/kubeadm/app/phases/addons/dns/manifests.go

@@ -309,7 +309,7 @@ data:
            fallthrough in-addr.arpa ip6.arpa
         }{{ .Federation }}
         prometheus :9153
-        proxy . {{ .UpstreamNameserver }}
+        forward . {{ .UpstreamNameserver }}
         cache 30
         loop
         reload