only load kubeconfig files one time

pkg/client/unversioned/clientcmd/client_config.go

@@ -67,25 +67,25 @@ type DirectClientConfig struct {
 
 // NewDefaultClientConfig creates a DirectClientConfig using the config.CurrentContext as the context name
 func NewDefaultClientConfig(config clientcmdapi.Config, overrides *ConfigOverrides) ClientConfig {
-	return DirectClientConfig{config, config.CurrentContext, overrides, nil}
+	return &DirectClientConfig{config, config.CurrentContext, overrides, nil}
 }
 
 // NewNonInteractiveClientConfig creates a DirectClientConfig using the passed context name and does not have a fallback reader for auth information
 func NewNonInteractiveClientConfig(config clientcmdapi.Config, contextName string, overrides *ConfigOverrides) ClientConfig {
-	return DirectClientConfig{config, contextName, overrides, nil}
+	return &DirectClientConfig{config, contextName, overrides, nil}
 }
 
 // NewInteractiveClientConfig creates a DirectClientConfig using the passed context name and a reader in case auth information is not provided via files or flags
 func NewInteractiveClientConfig(config clientcmdapi.Config, contextName string, overrides *ConfigOverrides, fallbackReader io.Reader) ClientConfig {
-	return DirectClientConfig{config, contextName, overrides, fallbackReader}
+	return &DirectClientConfig{config, contextName, overrides, fallbackReader}
 }
 
-func (config DirectClientConfig) RawConfig() (clientcmdapi.Config, error) {
+func (config *DirectClientConfig) RawConfig() (clientcmdapi.Config, error) {
 	return config.config, nil
 }
 
 // ClientConfig implements ClientConfig
-func (config DirectClientConfig) ClientConfig() (*client.Config, error) {
+func (config *DirectClientConfig) ClientConfig() (*client.Config, error) {
 	if err := config.ConfirmUsable(); err != nil {
 		return nil, err
 	}
@@ -217,7 +217,7 @@ func canIdentifyUser(config client.Config) bool {
 }
 
 // Namespace implements KubeConfig
-func (config DirectClientConfig) Namespace() (string, bool, error) {
+func (config *DirectClientConfig) Namespace() (string, bool, error) {
 	if err := config.ConfirmUsable(); err != nil {
 		return "", false, err
 	}
@@ -237,7 +237,7 @@ func (config DirectClientConfig) Namespace() (string, bool, error) {
 
 // ConfirmUsable looks a particular context and determines if that particular part of the config is useable.  There might still be errors in the config,
 // but no errors in the sections requested or referenced.  It does not return early so that it can find as many errors as possible.
-func (config DirectClientConfig) ConfirmUsable() error {
+func (config *DirectClientConfig) ConfirmUsable() error {
 	validationErrors := make([]error, 0)
 	validationErrors = append(validationErrors, validateAuthInfo(config.getAuthInfoName(), config.getAuthInfo())...)
 	validationErrors = append(validationErrors, validateClusterInfo(config.getClusterName(), config.getCluster())...)
@@ -249,7 +249,7 @@ func (config DirectClientConfig) ConfirmUsable() error {
 	return newErrConfigurationInvalid(validationErrors)
 }
 
-func (config DirectClientConfig) getContextName() string {
+func (config *DirectClientConfig) getContextName() string {
 	if len(config.overrides.CurrentContext) != 0 {
 		return config.overrides.CurrentContext
 	}
@@ -260,21 +260,21 @@ func (config DirectClientConfig) getContextName() string {
 	return config.config.CurrentContext
 }
 
-func (config DirectClientConfig) getAuthInfoName() string {
+func (config *DirectClientConfig) getAuthInfoName() string {
 	if len(config.overrides.Context.AuthInfo) != 0 {
 		return config.overrides.Context.AuthInfo
 	}
 	return config.getContext().AuthInfo
 }
 
-func (config DirectClientConfig) getClusterName() string {
+func (config *DirectClientConfig) getClusterName() string {
 	if len(config.overrides.Context.Cluster) != 0 {
 		return config.overrides.Context.Cluster
 	}
 	return config.getContext().Cluster
 }
 
-func (config DirectClientConfig) getContext() clientcmdapi.Context {
+func (config *DirectClientConfig) getContext() clientcmdapi.Context {
 	contexts := config.config.Contexts
 	contextName := config.getContextName()
 
@@ -287,7 +287,7 @@ func (config DirectClientConfig) getContext() clientcmdapi.Context {
 	return mergedContext
 }
 
-func (config DirectClientConfig) getAuthInfo() clientcmdapi.AuthInfo {
+func (config *DirectClientConfig) getAuthInfo() clientcmdapi.AuthInfo {
 	authInfos := config.config.AuthInfos
 	authInfoName := config.getAuthInfoName()
 
@@ -300,7 +300,7 @@ func (config DirectClientConfig) getAuthInfo() clientcmdapi.AuthInfo {
 	return mergedAuthInfo
 }
 
-func (config DirectClientConfig) getCluster() clientcmdapi.Cluster {
+func (config *DirectClientConfig) getCluster() clientcmdapi.Cluster {
 	clusterInfos := config.config.Clusters
 	clusterInfoName := config.getClusterName()
 

pkg/client/unversioned/clientcmd/loader.go

@@ -117,23 +117,41 @@ func (rules *ClientConfigLoadingRules) Load() (*clientcmdapi.Config, error) {
 
 	} else {
 		kubeConfigFiles = append(kubeConfigFiles, rules.Precedence...)
+	}
 
+	kubeconfigs := []*clientcmdapi.Config{}
+	// read and cache the config files so that we only look at them once
+	for _, filename := range kubeConfigFiles {
+		if len(filename) == 0 {
+			// no work to do
+			continue
+		}
+
+		config, err := LoadFromFile(filename)
+		if os.IsNotExist(err) {
+			// skip missing files
+			continue
+		}
+		if err != nil {
+			errlist = append(errlist, fmt.Errorf("Error loading config file \"%s\": %v", filename, err))
+			continue
+		}
+
+		kubeconfigs = append(kubeconfigs, config)
 	}
 
 	// first merge all of our maps
 	mapConfig := clientcmdapi.NewConfig()
-	for _, file := range kubeConfigFiles {
+	for _, kubeconfig := range kubeconfigs {
-		if err := mergeConfigWithFile(mapConfig, file); err != nil {
+		mergo.Merge(mapConfig, kubeconfig)
-			errlist = append(errlist, err)
-		}
 	}
 
 	// merge all of the struct values in the reverse order so that priority is given correctly
 	// errors are not added to the list the second time
 	nonMapConfig := clientcmdapi.NewConfig()
-	for i := len(kubeConfigFiles) - 1; i >= 0; i-- {
+	for i := len(kubeconfigs) - 1; i >= 0; i-- {
-		file := kubeConfigFiles[i]
+		kubeconfig := kubeconfigs[i]
-		mergeConfigWithFile(nonMapConfig, file)
+		mergo.Merge(nonMapConfig, kubeconfig)
 	}
 
 	// since values are overwritten, but maps values are not, we can merge the non-map config on top of the map config and
@@ -198,25 +216,6 @@ func (rules *ClientConfigLoadingRules) Migrate() error {
 	return nil
 }
 
-func mergeConfigWithFile(startingConfig *clientcmdapi.Config, filename string) error {
-	if len(filename) == 0 {
-		// no work to do
-		return nil
-	}
-
-	config, err := LoadFromFile(filename)
-	if os.IsNotExist(err) {
-		return nil
-	}
-	if err != nil {
-		return fmt.Errorf("Error loading config file \"%s\": %v", filename, err)
-	}
-
-	mergo.Merge(startingConfig, config)
-
-	return nil
-}
-
 // LoadFromFile takes a filename and deserializes the contents into Config object
 func LoadFromFile(filename string) (*clientcmdapi.Config, error) {
 	kubeconfigBytes, err := ioutil.ReadFile(filename)

pkg/client/unversioned/clientcmd/merged_client_builder.go

@@ -19,6 +19,7 @@ package clientcmd
 import (
 	"io"
 	"reflect"
+	"sync"
 
 	"github.com/golang/glog"
 
@@ -35,19 +36,27 @@ type DeferredLoadingClientConfig struct {
 	loadingRules   *ClientConfigLoadingRules
 	overrides      *ConfigOverrides
 	fallbackReader io.Reader
+
+	clientConfig ClientConfig
+	loadingLock  sync.Mutex
 }
 
 // NewNonInteractiveDeferredLoadingClientConfig creates a ConfigClientClientConfig using the passed context name
 func NewNonInteractiveDeferredLoadingClientConfig(loadingRules *ClientConfigLoadingRules, overrides *ConfigOverrides) ClientConfig {
-	return DeferredLoadingClientConfig{loadingRules, overrides, nil}
+	return &DeferredLoadingClientConfig{loadingRules: loadingRules, overrides: overrides}
 }
 
 // NewInteractiveDeferredLoadingClientConfig creates a ConfigClientClientConfig using the passed context name and the fallback auth reader
 func NewInteractiveDeferredLoadingClientConfig(loadingRules *ClientConfigLoadingRules, overrides *ConfigOverrides, fallbackReader io.Reader) ClientConfig {
-	return DeferredLoadingClientConfig{loadingRules, overrides, fallbackReader}
+	return &DeferredLoadingClientConfig{loadingRules: loadingRules, overrides: overrides, fallbackReader: fallbackReader}
 }
 
-func (config DeferredLoadingClientConfig) createClientConfig() (ClientConfig, error) {
+func (config *DeferredLoadingClientConfig) createClientConfig() (ClientConfig, error) {
+	if config.clientConfig == nil {
+		config.loadingLock.Lock()
+		defer config.loadingLock.Unlock()
+
+		if config.clientConfig == nil {
 			mergedConfig, err := config.loadingRules.Load()
 			if err != nil {
 				return nil, err
@@ -60,10 +69,14 @@ func (config DeferredLoadingClientConfig) createClientConfig() (ClientConfig, er
 				mergedClientConfig = NewNonInteractiveClientConfig(*mergedConfig, config.overrides.CurrentContext, config.overrides)
 			}
 
-	return mergedClientConfig, nil
+			config.clientConfig = mergedClientConfig
+		}
+	}
+
+	return config.clientConfig, nil
 }
 
-func (config DeferredLoadingClientConfig) RawConfig() (clientcmdapi.Config, error) {
+func (config *DeferredLoadingClientConfig) RawConfig() (clientcmdapi.Config, error) {
 	mergedConfig, err := config.createClientConfig()
 	if err != nil {
 		return clientcmdapi.Config{}, err
@@ -73,7 +86,7 @@ func (config DeferredLoadingClientConfig) RawConfig() (clientcmdapi.Config, erro
 }
 
 // ClientConfig implements ClientConfig
-func (config DeferredLoadingClientConfig) ClientConfig() (*client.Config, error) {
+func (config *DeferredLoadingClientConfig) ClientConfig() (*client.Config, error) {
 	mergedClientConfig, err := config.createClientConfig()
 	if err != nil {
 		return nil, err
@@ -94,7 +107,7 @@ func (config DeferredLoadingClientConfig) ClientConfig() (*client.Config, error)
 }
 
 // Namespace implements KubeConfig
-func (config DeferredLoadingClientConfig) Namespace() (string, bool, error) {
+func (config *DeferredLoadingClientConfig) Namespace() (string, bool, error) {
 	mergedKubeConfig, err := config.createClientConfig()
 	if err != nil {
 		return "", false, err