Update eviction util implementation.

pkg/rescheduler/evictions/utils/utils.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2017 The Kubernetes 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 utils
+
+import (
+	"k8s.io/kubernetes/pkg/client/clientset_generated/clientset"
+)
+
+const (
+	EvictionKind        = "Eviction"
+	EvictionSubresource = "pods/eviction"
+)
+
+// SupportEviction uses Discovery API to find out if the server support eviction subresource
+// If support, it will return its groupVersion; Otherwise, it will return ""
+func SupportEviction(clientset clientset.Interface) (string, error) {
+	discoveryClient := clientset.Discovery()
+	groupList, err := discoveryClient.ServerGroups()
+	if err != nil {
+		return "", err
+	}
+	foundPolicyGroup := false
+	var policyGroupVersion string
+	for _, group := range groupList.Groups {
+		if group.Name == "policy" {
+			foundPolicyGroup = true
+			policyGroupVersion = group.PreferredVersion.GroupVersion
+			break
+		}
+	}
+	if !foundPolicyGroup {
+		return "", nil
+	}
+	resourceList, err := discoveryClient.ServerResourcesForGroupVersion("v1")
+	if err != nil {
+		return "", err
+	}
+	for _, resource := range resourceList.APIResources {
+		if resource.Name == EvictionSubresource && resource.Kind == EvictionKind {
+			return policyGroupVersion, nil
+		}
+	}
+	return "", nil
+}