Added kubernetes provider singleton (#599)

agent/pkg/providers/kubernetes_provider.go

@@ -0,0 +1,27 @@
+package providers
+
+import (
+	"github.com/up9inc/mizu/shared/kubernetes"
+	"sync"
+)
+
+var lock = &sync.Mutex{}
+
+var kubernetesProvider *kubernetes.Provider
+
+func GetKubernetesProvider() (*kubernetes.Provider, error) {
+	if kubernetesProvider == nil {
+		lock.Lock()
+		defer lock.Unlock()
+
+		if kubernetesProvider == nil {
+			var err error
+			kubernetesProvider, err = kubernetes.NewProviderInCluster()
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return kubernetesProvider, nil
+}