Allow initializing the Kubernetes client with a kubeconfig

This makes it so that the API server will first try the in-cluster
configuration and fallback to a kubeconfig. This is helpful when the API
server is running outside of the cluster (e.g. locally) so you don't
need to create token files.

Signed-off-by: mprahl <[email protected]>

backend/src/apiserver/client/util.go

@@ -15,15 +15,15 @@
 package client
 
 import (
+	"os"
+
 	"github.com/kubeflow/pipelines/backend/src/common/util"
 	"github.com/pkg/errors"
 	"k8s.io/client-go/kubernetes"
-	"k8s.io/client-go/rest"
-	"os"
 )
 
 func getKubernetesClientset(clientParams util.ClientParameters) (*kubernetes.Clientset, error) {
-	restConfig, err := rest.InClusterConfig()
+	restConfig, err := util.GetKubernetesConfig()
 	if err != nil {
 		return nil, errors.Wrap(err, "Failed to initialize kubernetes client")
 	}

backend/src/common/util/execution_client.go

@@ -87,7 +87,7 @@ func NewExecutionClientOrFatal(execType ExecutionType, initConnectionTimeout tim
 	case ArgoWorkflow:
 		var argoProjClient *argoclient.Clientset
 		operation := func() error {
-			restConfig, err := rest.InClusterConfig()
+			restConfig, err := GetKubernetesConfig()
 			if err != nil {
 				return errors.Wrap(err, "Failed to initialize the RestConfig")
 			}

backend/src/common/util/service.go

@@ -50,6 +50,26 @@ func WaitForAPIAvailable(initializeTimeout time.Duration, basePath string, apiAd
 	return errors.Wrapf(err, "Waiting for ml pipeline API server failed after all attempts.")
 }
 
+// GetKubernetesConfig will first try an in-cluster configuration but fallback to using a kubeconfig.
+func GetKubernetesConfig() (*rest.Config, error) {
+	restConfig, errInCluster := rest.InClusterConfig()
+	if errInCluster == nil {
+		return restConfig, nil
+	}
+
+	// Fallback to using a kubeconfig
+	clientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
+		clientcmd.NewDefaultClientConfigLoadingRules(), &clientcmd.ConfigOverrides{},
+	)
+
+	restConfig, errKubeconfig := clientConfig.ClientConfig()
+	if errKubeconfig != nil {
+		return nil, fmt.Errorf("%w; %w", errInCluster, errKubeconfig)
+	}
+
+	return restConfig, nil
+}
+
 func GetKubernetesClientFromClientConfig(clientConfig clientcmd.ClientConfig) (
 	*kubernetes.Clientset, *rest.Config, string, error,
 ) {