pkg/apihelpers: split out loading of kubeconfig to a separate function

Make kubeconfig loading and parsing re-usable for multiple clients.

pkg/apihelper/k8shelpers.go

@@ -31,24 +31,11 @@ import (
 
 // Implements APIHelpers
 type K8sHelpers struct {
-	Kubeconfig string
+	Kubeconfig *restclient.Config
 }
 
 func (h K8sHelpers) GetClient() (*k8sclient.Clientset, error) {
-	// Set up an in-cluster K8S client.
-	var config *restclient.Config
-	var err error
-
-	if h.Kubeconfig == "" {
-		config, err = restclient.InClusterConfig()
-	} else {
-		config, err = clientcmd.BuildConfigFromFlags("", h.Kubeconfig)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	clientset, err := k8sclient.NewForConfig(config)
+	clientset, err := k8sclient.NewForConfig(h.Kubeconfig)
 	if err != nil {
 		return nil, err
 	}
@@ -56,20 +43,7 @@ func (h K8sHelpers) GetClient() (*k8sclient.Clientset, error) {
 }
 
 func (h K8sHelpers) GetTopologyClient() (*topologyclientset.Clientset, error) {
-	// Set up an in-cluster K8S client.
-	var config *restclient.Config
-	var err error
-
-	if h.Kubeconfig == "" {
-		config, err = restclient.InClusterConfig()
-	} else {
-		config, err = clientcmd.BuildConfigFromFlags("", h.Kubeconfig)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	topologyClient, err := topologyclientset.NewForConfig(config)
+	topologyClient, err := topologyclientset.NewForConfig(h.Kubeconfig)
 	if err != nil {
 		return nil, err
 	}
@@ -132,3 +106,10 @@ func (h K8sHelpers) GetPod(cli *k8sclient.Clientset, namespace string, podName s
 
 	return pod, nil
 }
+
+func GetKubeconfig(path string) (*restclient.Config, error) {
+	if path == "" {
+		return restclient.InClusterConfig()
+	}
+	return clientcmd.BuildConfigFromFlags("", path)
+}

pkg/nfd-client/topology-updater/nfd-topology-updater.go

@@ -91,7 +91,15 @@ func (w *nfdTopologyUpdater) Run() error {
 		return fmt.Errorf("failed to get PodResource Client: %w", err)
 	}
 
-	kubeApihelper := apihelper.K8sHelpers{Kubeconfig: w.args.KubeConfigFile}
+	var kubeApihelper apihelper.K8sHelpers
+	if !w.args.NoPublish {
+		kubeconfig, err := apihelper.GetKubeconfig(w.args.KubeConfigFile)
+		if err != nil {
+			return err
+		}
+		kubeApihelper = apihelper.K8sHelpers{Kubeconfig: kubeconfig}
+	}
+
 	var resScan resourcemonitor.ResourcesScanner
 
 	resScan, err = resourcemonitor.NewPodResourcesScanner(w.resourcemonitorArgs.Namespace, podResClient, kubeApihelper)

pkg/nfd-master/nfd-master.go

@@ -39,6 +39,7 @@ import (
 	api "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	restclient "k8s.io/client-go/rest"
 	"k8s.io/klog/v2"
 
 	"sigs.k8s.io/node-feature-discovery/pkg/apihelper"
@@ -110,6 +111,7 @@ type nfdMaster struct {
 	stop         chan struct{}
 	ready        chan bool
 	apihelper    apihelper.APIHelpers
+	kubeconfig   *restclient.Config
 }
 
 // Create new NfdMaster server instance.
@@ -145,7 +147,13 @@ func NewNfdMaster(args *Args) (NfdMaster, error) {
 	}
 
 	// Initialize Kubernetes API helpers
-	nfd.apihelper = apihelper.K8sHelpers{Kubeconfig: args.Kubeconfig}
+	if !args.NoPublish {
+		kubeconfig, err := nfd.getKubeconfig()
+		if err != nil {
+			return nfd, err
+		}
+		nfd.apihelper = apihelper.K8sHelpers{Kubeconfig: kubeconfig}
+	}
 
 	return nfd, nil
 }
@@ -519,6 +527,14 @@ func (m *nfdMaster) annotationName(name string) string {
 	return path.Join(m.annotationNs, name)
 }
 
+func (m *nfdMaster) getKubeconfig() (*restclient.Config, error) {
+	var err error
+	if m.kubeconfig == nil {
+		m.kubeconfig, err = apihelper.GetKubeconfig(m.args.Kubeconfig)
+	}
+	return m.kubeconfig, err
+}
+
 // Remove any labels having the given prefix
 func removeLabelsWithPrefix(n *api.Node, search string) []apihelper.JsonPatch {
 	var p []apihelper.JsonPatch