Kubernetes Config Update: Prioritize InClusterConfig function

cmd/controller/main.go

@@ -49,7 +49,6 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/client-go/tools/leaderelection"
 	"k8s.io/client-go/tools/leaderelection/resourcelock"
 )
@@ -133,8 +132,8 @@ func main() {
 		logger.Fatal("Could not create controller from environment or flags")
 	}
 
-	// if the kubeconfig fails BuildConfigFromFlags will try in cluster config
-	clientConf, err := clientcmd.BuildConfigFromFlags("", ctlConf.KubeConfig)
+	// if the kubeconfig fails InClusterBuildConfig will try in cluster config
+	clientConf, err := runtime.InClusterBuildConfig(ctlConf.KubeConfig)
 	if err != nil {
 		logger.WithError(err).Fatal("Could not create in cluster config")
 	}

cmd/extensions/main.go

@@ -48,7 +48,6 @@ import (
 	"gopkg.in/natefinch/lumberjack.v2"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/tools/clientcmd"
 )
 
 const (
@@ -114,8 +113,8 @@ func main() {
 	logger.WithField("version", pkg.Version).WithField("featureGates", runtime.EncodeFeatures()).
 		WithField("ctlConf", ctlConf).Info("starting extensions operator...")
 
-	// if the kubeconfig fails BuildConfigFromFlags will try in cluster config
-	clientConf, err := clientcmd.BuildConfigFromFlags("", ctlConf.KubeConfig)
+	// if the kubeconfig fails InClusterBuildConfig will try in cluster config
+	clientConf, err := runtime.InClusterBuildConfig(ctlConf.KubeConfig)
 	if err != nil {
 		logger.WithError(err).Fatal("Could not create in cluster config")
 	}

cmd/sdk-server/main.go

@@ -42,7 +42,6 @@ import (
 	"google.golang.org/grpc/credentials/insecure"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
-	"k8s.io/client-go/tools/clientcmd"
 )
 
 const (
@@ -119,8 +118,8 @@ func main() {
 		}
 	default:
 		var config *rest.Config
-		// if the kubeconfig fails BuildConfigFromFlags will try in cluster config
-		config, err := clientcmd.BuildConfigFromFlags("", ctlConf.KubeConfig)
+		// if the kubeconfig fails InClusterBuildConfig will try in cluster config
+		config, err := runtime.InClusterBuildConfig(ctlConf.KubeConfig)
 		if err != nil {
 			logger.WithError(err).Fatal("Could not create in cluster config")
 		}

pkg/util/runtime/runtime.go

@@ -25,6 +25,9 @@ import (
 	"github.com/sirupsen/logrus"
 	"google.golang.org/protobuf/encoding/protojson"
 	"k8s.io/apimachinery/pkg/util/runtime"
+	restclient "k8s.io/client-go/rest"
+	clientcmd "k8s.io/client-go/tools/clientcmd"
+	"k8s.io/klog"
 )
 
 const sourceKey = "source"
@@ -110,3 +113,24 @@ func NewServerMux() *gwruntime.ServeMux {
 	)
 	return mux
 }
+
+// InClusterBuildConfig is a helper function that first attempts to build configurations
+// using InClusterConfig(). If InClusterConfig is unsuccessful, it then tries to build
+// configurations from a kubeconfigPath. This path is typically passed in as a command line
+// flag for cluster components. If neither the InClusterConfig nor the kubeconfigPath
+// are successful, the function logs a warning and falls back to a default configuration.
+func InClusterBuildConfig(kubeconfigPath string) (*restclient.Config, error) {
+	kubeconfig, err := restclient.InClusterConfig()
+	if err == nil {
+		return kubeconfig, nil
+	}
+	klog.Warning("error creating inClusterConfig, trying to build config from flags", err)
+
+	if kubeconfigPath == "" {
+		klog.Warning("No kubeconfigPath provided. Attempting to use a default configuration.")
+	}
+
+	return clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
+		&clientcmd.ClientConfigLoadingRules{ExplicitPath: kubeconfigPath},
+		&clientcmd.ConfigOverrides{}).ClientConfig()
+}

test/e2e/framework/framework.go

@@ -53,7 +53,6 @@ import (
 
 	// required to use gcloud login see: https://github.com/kubernetes/client-go/issues/242
 	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
-	"k8s.io/client-go/tools/clientcmd"
 )
 
 // special labels that can be put on pods to trigger automatic cleanup.
@@ -81,7 +80,7 @@ type Framework struct {
 }
 
 func newFramework(kubeconfig string, qps float32, burst int) (*Framework, error) {
-	config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
+	config, err := runtime.InClusterBuildConfig(kubeconfig)
 	if err != nil {
 		return nil, errors.Wrap(err, "build config from flags failed")
 	}

test/eviction/evictpod.go

@@ -22,10 +22,10 @@ import (
 	"log"
 	"path/filepath"
 
+	"agones.dev/agones/pkg/util/runtime"
 	policy "k8s.io/api/policy/v1"
 	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/tools/clientcmd"
 	"k8s.io/client-go/util/homedir"
 )
 
@@ -50,7 +50,7 @@ func main() {
 		log.Fatal("--pod must be non-empty")
 	}
 
-	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
+	config, err := runtime.InClusterBuildConfig(*kubeconfig)
 	if err != nil {
 		log.Fatalf("Could not build config: %v", err)
 	}