add bind-api and a getter for kube client

This adds the bind API plus a getter for the kube client and makes
the NewMetricsExtender return a pointer.

Signed-off-by: Ukri Niemimuukko <ukri.niemimuukko@intel.com>

Author: uniemimu

extender/client.go

@@ -0,0 +1,26 @@
+package extender
+
+import (
+	"log"
+
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+// GetKubeClient returns the kube client interface with its config.
+func GetKubeClient(kubeConfig string) (kubernetes.Interface, *rest.Config, error) {
+	clientConfig, err := rest.InClusterConfig()
+	if err != nil {
+		log.Print("not in cluster - trying file-based configuration")
+		clientConfig, err = clientcmd.BuildConfigFromFlags("", kubeConfig)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	kubeClient, err := kubernetes.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, nil, err
+	}
+	return kubeClient, clientConfig, nil
+}

extender/go.mod

@@ -2,4 +2,9 @@ module github.com/intel/platform-aware-scheduling/extender
 
 go 1.15
 
-require k8s.io/api v0.20.2
+require (
+	k8s.io/api v0.20.2
+	k8s.io/apimachinery v0.20.2
+	k8s.io/client-go v0.20.2
+	k8s.io/klog/v2 v2.4.0
+)