Introduce LoadRESTConfig function pointer

This way, the way the REST config is loaded is up to the client factory
users. The special "admin" settings are now part of the controller
command, freeing the client factory from any particular way of loading
and setting up the config.

Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>

cmd/controller/controller.go

@@ -58,6 +58,7 @@ import (
 	"github.com/k0sproject/k0s/pkg/token"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"k8s.io/client-go/rest"
 )
 
 type command config.CLIOptions
@@ -162,7 +163,20 @@ func (c *command) start(ctx context.Context) error {
 	}()
 
 	// common factory to get the admin kube client that's needed in many components
-	adminClientFactory := kubernetes.NewAdminClientFactory(c.K0sVars.AdminKubeConfigPath)
+	adminClientFactory := &kubernetes.ClientFactory{LoadRESTConfig: func() (*rest.Config, error) {
+		config, err := kubernetes.ClientConfig(kubernetes.KubeconfigFromFile(c.K0sVars.AdminKubeConfigPath))
+		if err != nil {
+			return nil, err
+		}
+
+		// We're always running the client on the same host as the API, no need to compress
+		config.DisableCompression = true
+		// To mitigate stack applier bursts in startup
+		config.QPS = 40.0
+		config.Burst = 400.0
+
+		return config, nil
+	}}
 
 	certificateManager := certificate.Manager{K0sVars: c.K0sVars}
 

pkg/kubernetes/client.go

@@ -17,7 +17,6 @@ limitations under the License.
 package kubernetes
 
 import (
-	"fmt"
 	"sync"
 
 	k0sclientset "github.com/k0sproject/k0s/pkg/client/clientset"
@@ -44,18 +43,11 @@ type ClientFactoryInterface interface {
 	GetEtcdMemberClient() (etcdMemberClient.EtcdMemberInterface, error) // Deprecated: Use [ClientFactoryInterface.GetK0sClient] instead.
 }
 
-// NewAdminClientFactory creates a new factory that loads the admin kubeconfig based client
-func NewAdminClientFactory(kubeconfigPath string) ClientFactoryInterface {
-	return &ClientFactory{
-		configPath: kubeconfigPath,
-	}
-}
-
 // ClientFactory implements a cached and lazy-loading ClientFactory for all the different types of kube clients we use
 // It's imoplemented as lazy-loading so we can create the factory itself before we have the api, etcd and other components up so we can pass
 // the factory itself to components needing kube clients and creation time.
 type ClientFactory struct {
-	configPath string
+	LoadRESTConfig func() (*rest.Config, error)
 
 	client          kubernetes.Interface
 	dynamicClient   dynamic.Interface
@@ -190,15 +182,10 @@ func (c *ClientFactory) getRESTConfig() (*rest.Config, error) {
 		return c.restConfig, nil
 	}
 
-	config, err := clientcmd.BuildConfigFromFlags("", c.configPath)
+	config, err := c.LoadRESTConfig()
 	if err != nil {
-		return nil, fmt.Errorf("failed to load kubeconfig: %w", err)
+		return nil, err
 	}
-	// We're always running the client on the same host as the API, no need to compress
-	config.DisableCompression = true
-	// To mitigate stack applier bursts in startup
-	config.QPS = 40.0
-	config.Burst = 400.0
 
 	c.restConfig = config