Use direct function call.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/constants/constants.go

@@ -0,0 +1,26 @@
+/*
+Copyright 2018 The Containerd Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package constants
+
+// TODO(random-liu): Merge annotations package into this package.
+
+const (
+	// K8sContainerdNamespace is the namespace we use to connect containerd.
+	K8sContainerdNamespace = "k8s.io"
+	// CRIVersion is the CRI version supported by the CRI plugin.
+	CRIVersion = "v1alpha2"
+)