WIP safe getrestclient without a map again

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

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"
@@ -48,30 +47,34 @@ type ClientFactoryInterface interface {
 func NewAdminClientFactory(kubeconfigPath string) ClientFactoryInterface {
 	return &clientFactory{
 		configPath: kubeconfigPath,
-		cache:      make(map[any]any, 8),
 	}
 }
 
 // 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
+// It's implemented 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
 
+	client          *kubernetes.Clientset
+	dynamicClient   *dynamic.DynamicClient
+	discoveryClient discovery.CachedDiscoveryInterface
+	k0sClient       *k0sclientset.Clientset
+	restConfig      *rest.Config
+
 	mutex sync.Mutex
-	cache map[any]any
 }
 
 func (c *clientFactory) GetClient() (kubernetes.Interface, error) {
-	return getOrCreateClient(c, kubernetes.NewForConfig)
+	return getOrCreateClient(c, &c.client, kubernetes.NewForConfig)
 }
 
 func (c *clientFactory) GetDynamicClient() (dynamic.Interface, error) {
-	return getOrCreateClient(c, dynamic.NewForConfig)
+	return getOrCreateClient(c, &c.dynamicClient, dynamic.NewForConfig)
 }
 
 func (c *clientFactory) GetDiscoveryClient() (discovery.CachedDiscoveryInterface, error) {
-	return getOrCreateClient(c, func(c *rest.Config) (discovery.CachedDiscoveryInterface, error) {
+	return getOrCreateClient(c, &c.discoveryClient, func(c *rest.Config) (discovery.CachedDiscoveryInterface, error) {
 		discoveryClient, err := discovery.NewDiscoveryClientForConfig(c)
 		if err != nil {
 			return nil, err
@@ -81,10 +84,10 @@ func (c *clientFactory) GetDiscoveryClient() (discovery.CachedDiscoveryInterface
 }
 
 func (c *clientFactory) GetK0sClient() (k0sclientset.Interface, error) {
-	return getOrCreateClient(c, k0sclientset.NewForConfig)
+	return getOrCreateClient(c, &c.k0sClient, k0sclientset.NewForConfig)
 }
 
-// Deprecated: Use [ClientFactory.GetK0sClient] instead.
+// Deprecated: Use [clientFactory.GetK0sClient] instead.
 func (c *clientFactory) GetConfigClient() (cfgClient.ClusterConfigInterface, error) {
 	k0sClient, err := c.GetK0sClient()
 	if err != nil {
@@ -94,7 +97,7 @@ func (c *clientFactory) GetConfigClient() (cfgClient.ClusterConfigInterface, err
 	return k0sClient.K0sV1beta1().ClusterConfigs(constant.ClusterConfigNamespace), nil
 }
 
-// Deprecated: Use [ClientFactory.GetK0sClient] instead.
+// Deprecated: Use [clientFactory.GetK0sClient] instead.
 func (c *clientFactory) GetEtcdMemberClient() (etcdMemberClient.EtcdMemberInterface, error) {
 	k0sClient, err := c.GetK0sClient()
 	if err != nil {
@@ -107,25 +110,53 @@ func (c *clientFactory) GetEtcdMemberClient() (etcdMemberClient.EtcdMemberInterf
 func (c *clientFactory) GetRESTConfig() (*rest.Config, error) {
 	c.mutex.Lock()
 	defer c.mutex.Unlock()
-	return c.getRESTConfig()
+	config, err := c.getRESTConfig()
+	if err != nil {
+		return nil, err
+	}
+	return rest.CopyConfig(config), nil
 }
 
 func (c *clientFactory) getRESTConfig() (*rest.Config, error) {
-	return getOrCreate(c, func() (*rest.Config, error) {
-		restConfig, err := clientcmd.BuildConfigFromFlags("", c.configPath)
+	return getOrCreate(&c.restConfig, func() (*rest.Config, error) {
+		config, err := ClientConfig(KubeconfigFromFile(c.configPath))
 		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
-		restConfig.DisableCompression = true
+		config.DisableCompression = true
 		// To mitigate stack applier bursts in startup
-		restConfig.QPS = 40.0
-		restConfig.Burst = 400.0
+		config.QPS = 40.0
+		config.Burst = 400.0
+
+		return config, nil
+	})
+}
+
+func getOrCreateClient[T comparable](cf *clientFactory, loaded *T, newForConfig func(*rest.Config) (T, error)) (T, error) {
+	cf.mutex.Lock()
+	defer cf.mutex.Unlock()
 
-		return restConfig, nil
+	return getOrCreate(loaded, func() (t T, _ error) {
+		config, err := cf.getRESTConfig()
+		if err != nil {
+			return t, err
+		}
+		return newForConfig(config)
 	})
 }
 
+func getOrCreate[T comparable](loaded *T, load func() (T, error)) (t T, err error) {
+	if *loaded == t {
+		t, err = load()
+		if err == nil {
+			*loaded = t
+		}
+	}
+	return *loaded, err
+}
+
 // KubeconfigFromFile returns a [clientcmd.KubeconfigGetter] that tries to load
 // a kubeconfig from the given path.
 func KubeconfigFromFile(path string) clientcmd.KubeconfigGetter {
@@ -158,32 +189,3 @@ func NewClient(getter clientcmd.KubeconfigGetter) (kubernetes.Interface, error)
 
 	return kubernetes.NewForConfig(config)
 }
-
-func getOrCreateClient[T any](c *clientFactory, newForConfig func(*rest.Config) (T, error)) (T, error) {
-	c.mutex.Lock()
-	defer c.mutex.Unlock()
-
-	return getOrCreate(c, func() (t T, _ error) {
-		c, err := c.getRESTConfig()
-		if err != nil {
-			return t, err
-		}
-		return newForConfig(c)
-	})
-}
-
-func getOrCreate[T any](c *clientFactory, create func() (T, error)) (T, error) {
-	// A unique key based on the type of a value.
-	type keyType[T any] struct{}
-
-	k := keyType[T]{}
-	if stored, ok := c.cache[k].(*T); ok && stored != nil {
-		return *stored, nil
-	}
-
-	loaded, err := create()
-	if err == nil {
-		c.cache[k] = &loaded
-	}
-	return loaded, err
-}