Limit the type for kubectl expose command

pkg/kubectl/cmd/util/factory.go

@@ -86,6 +86,8 @@ type Factory struct {
 	DefaultNamespace func() (string, bool, error)
 	// Returns the generator for the provided generator name
 	Generator func(name string) (kubectl.Generator, bool)
+	// Check whether the kind of resources could be exposed
+	CanBeExposed func(kind string) error
 }
 
 // NewFactory creates a factory with the default Kubernetes resources defined
@@ -246,6 +248,12 @@ func NewFactory(optionalClientConfig clientcmd.ClientConfig) *Factory {
 			generator, ok := generators[name]
 			return generator, ok
 		},
+		CanBeExposed: func(kind string) error {
+			if kind != "ReplicationController" && kind != "Service" && kind != "Pod" {
+				return fmt.Errorf("invalid resource provided: %v, only a replication controller, service or pod is accepted", kind)
+			}
+			return nil
+		},
 	}
 }
 

pkg/kubectl/cmd/util/factory_test.go

@@ -165,6 +165,33 @@ func TestLabelsForObject(t *testing.T) {
 	}
 }
 
+func TestCanBeExposed(t *testing.T) {
+	factory := NewFactory(nil)
+	tests := []struct {
+		kind      string
+		expectErr bool
+	}{
+		{
+			kind:      "ReplicationController",
+			expectErr: false,
+		},
+		{
+			kind:      "Node",
+			expectErr: true,
+		},
+	}
+
+	for _, test := range tests {
+		err := factory.CanBeExposed(test.kind)
+		if test.expectErr && err == nil {
+			t.Error("unexpected non-error")
+		}
+		if !test.expectErr && err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+	}
+}
+
 func TestFlagUnderscoreRenaming(t *testing.T) {
 	factory := NewFactory(nil)