Concurrency safe client factory

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}
 
@@ -561,7 +575,11 @@ func (c *command) start(ctx context.Context) error {
 		EnableWorker:       c.EnableWorker,
 	})
 
-	apClientFactory, err := apclient.NewClientFactory(adminClientFactory.GetRESTConfig())
+	restConfig, err := adminClientFactory.GetRESTConfig()
+	if err != nil {
+		return err
+	}
+	apClientFactory, err := apclient.NewClientFactory(restConfig)
 	if err != nil {
 		return err
 	}

internal/testutil/kube_client.go

@@ -17,11 +17,11 @@ limitations under the License.
 package testutil
 
 import (
-	"errors"
 	"reflect"
 	"strings"
 
 	"github.com/k0sproject/k0s/internal/testutil/fakeclient"
+	k0sclientset "github.com/k0sproject/k0s/pkg/client/clientset"
 	k0sfake "github.com/k0sproject/k0s/pkg/client/clientset/fake"
 	k0sscheme "github.com/k0sproject/k0s/pkg/client/clientset/scheme"
 	etcdv1beta1 "github.com/k0sproject/k0s/pkg/client/clientset/typed/etcd/v1beta1"
@@ -69,20 +69,18 @@ func NewFakeClientFactory(objects ...runtime.Object) *FakeClientFactory {
 	k0sClients := fakeclient.NewClientset[k0sfake.Clientset](fakeDiscovery, tracker)
 
 	return &FakeClientFactory{
-		DynamicClient:    fakeDynamic,
-		Client:           kubeClients,
-		DiscoveryClient:  memory.NewMemCacheClient(fakeDiscovery),
-		ConfigClient:     k0sClients.K0sV1beta1().ClusterConfigs(constant.ClusterConfigNamespace),
-		EtcdMemberClient: k0sClients.EtcdV1beta1().EtcdMembers(),
+		DynamicClient:   fakeDynamic,
+		Client:          kubeClients,
+		DiscoveryClient: memory.NewMemCacheClient(fakeDiscovery),
+		K0sClient:       k0sClients,
 	}
 }
 
 type FakeClientFactory struct {
-	DynamicClient    *dynamicfake.FakeDynamicClient
-	Client           kubernetes.Interface
-	DiscoveryClient  discovery.CachedDiscoveryInterface
-	ConfigClient     k0sv1beta1.ClusterConfigInterface
-	EtcdMemberClient etcdv1beta1.EtcdMemberInterface
+	DynamicClient   *dynamicfake.FakeDynamicClient
+	Client          kubernetes.Interface
+	DiscoveryClient discovery.CachedDiscoveryInterface
+	K0sClient       k0sclientset.Interface
 }
 
 func (f *FakeClientFactory) GetClient() (kubernetes.Interface, error) {
@@ -97,20 +95,22 @@ func (f *FakeClientFactory) GetDiscoveryClient() (discovery.CachedDiscoveryInter
 	return f.DiscoveryClient, nil
 }
 
-func (f *FakeClientFactory) GetConfigClient() (k0sv1beta1.ClusterConfigInterface, error) {
-	return f.ConfigClient, nil
+func (f *FakeClientFactory) GetK0sClient() (k0sclientset.Interface, error) {
+	return f.K0sClient, nil
 }
 
-func (f *FakeClientFactory) GetRESTClient() (rest.Interface, error) {
-	return nil, errors.ErrUnsupported
+// Deprecated: Use [FakeClientFactory.GetK0sClient] instead.
+func (f *FakeClientFactory) GetConfigClient() (k0sv1beta1.ClusterConfigInterface, error) {
+	return f.K0sClient.K0sV1beta1().ClusterConfigs(constant.ClusterConfigNamespace), nil
 }
 
-func (f FakeClientFactory) GetRESTConfig() *rest.Config {
-	return &rest.Config{}
+func (f FakeClientFactory) GetRESTConfig() (*rest.Config, error) {
+	panic("GetRESTConfig not implemented for FakeClientFactory")
 }
 
+// Deprecated: Use [FakeClientFactory.GetK0sClient] instead.
 func (f FakeClientFactory) GetEtcdMemberClient() (etcdv1beta1.EtcdMemberInterface, error) {
-	return f.EtcdMemberClient, nil
+	return f.K0sClient.EtcdV1beta1().EtcdMembers(), nil
 }
 
 // Extracts all kinds from scheme and builds API resource lists for fake discovery clients.

pkg/applier/stack.go

@@ -155,7 +155,11 @@ func (s *Stack) Apply(ctx context.Context, prune bool) error {
 
 // waitForCRD waits 5 seconds for a CRD to become established on a best-effort basis.
 func (s *Stack) waitForCRD(ctx context.Context, crdName string) {
-	client, err := extensionsclient.NewForConfig(s.Clients.GetRESTConfig())
+	config, err := s.Clients.GetRESTConfig()
+	if err != nil {
+		return
+	}
+	client, err := extensionsclient.NewForConfig(config)
 	if err != nil {
 		return
 	}

pkg/autopilot/checks/checks.go

@@ -42,11 +42,7 @@ func CanUpdate(ctx context.Context, log logrus.FieldLogger, clientFactory kubern
 		}
 	}
 
-	metaClient, err := metadata.NewForConfig(clientFactory.GetRESTConfig())
-	if err != nil {
-		return err
-	}
-
+	var metaClient metadata.Interface
 	for _, r := range resources {
 		gv, err := schema.ParseGroupVersion(r.GroupVersion)
 		if err != nil {
@@ -69,6 +65,17 @@ func CanUpdate(ctx context.Context, log logrus.FieldLogger, clientFactory kubern
 				continue
 			}
 
+			if metaClient == nil {
+				restConfig, err := clientFactory.GetRESTConfig()
+				if err != nil {
+					return err
+				}
+
+				if metaClient, err = metadata.NewForConfig(restConfig); err != nil {
+					return err
+				}
+			}
+
 			metas, err := metaClient.Resource(gv.WithResource(ar.Name)).
 				Namespace(metav1.NamespaceAll).
 				List(ctx, metav1.ListOptions{})

pkg/component/controller/autopilot.go

@@ -46,7 +46,11 @@ func (a *Autopilot) Init(ctx context.Context) error {
 func (a *Autopilot) Start(ctx context.Context) error {
 	log := logrus.WithFields(logrus.Fields{"component": "autopilot"})
 
-	autopilotClientFactory, err := apcli.NewClientFactory(a.AdminClientFactory.GetRESTConfig())
+	restConfig, err := a.AdminClientFactory.GetRESTConfig()
+	if err != nil {
+		return fmt.Errorf("creating autopilot client factory error: %w", err)
+	}
+	autopilotClientFactory, err := apcli.NewClientFactory(restConfig)
 	if err != nil {
 		return fmt.Errorf("creating autopilot client factory error: %w", err)
 	}

pkg/component/controller/etcd_member_reconciler.go

@@ -126,8 +126,10 @@ func (e *EtcdMemberReconciler) Stop() error {
 }
 
 func (e *EtcdMemberReconciler) waitForCRD(ctx context.Context) error {
-	rc := e.clientFactory.GetRESTConfig()
-
+	rc, err := e.clientFactory.GetRESTConfig()
+	if err != nil {
+		return err
+	}
 	ec, err := extclient.NewForConfig(rc)
 	if err != nil {
 		return err

pkg/component/controller/metrics.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"net/http"
 	"os"
@@ -32,7 +33,7 @@ import (
 	"github.com/k0sproject/k0s/pkg/apis/k0s/v1beta1"
 	"github.com/k0sproject/k0s/pkg/component/manager"
 	"github.com/k0sproject/k0s/pkg/config"
-	"github.com/k0sproject/k0s/pkg/kubernetes"
+	kubeutil "github.com/k0sproject/k0s/pkg/kubernetes"
 	"github.com/sirupsen/logrus"
 )
 
@@ -60,15 +61,20 @@ var _ manager.Component = (*Metrics)(nil)
 var _ manager.Reconciler = (*Metrics)(nil)
 
 // NewMetrics creates new Metrics reconciler
-func NewMetrics(k0sVars *config.CfgVars, saver manifestsSaver, clientCF kubernetes.ClientFactoryInterface, storageType v1beta1.StorageType) (*Metrics, error) {
+func NewMetrics(k0sVars *config.CfgVars, saver manifestsSaver, clientCF kubeutil.ClientFactoryInterface, storageType v1beta1.StorageType) (*Metrics, error) {
 	hostname, err := os.Hostname()
 	if err != nil {
 		return nil, err
 	}
 
-	restClient, err := clientCF.GetRESTClient()
-	if err != nil {
+	var restClient rest.Interface
+	if client, err := clientCF.GetDiscoveryClient(); err != nil {
 		return nil, fmt.Errorf("error getting REST client for metrics: %w", err)
+	} else {
+		restClient = client.RESTClient()
+	}
+	if restClient == nil {
+		return nil, errors.New("no REST client for metrics")
 	}
 
 	return &Metrics{