Updating the federation cluster controller to use secretRef to contact the server

federation/pkg/federation-controller/cluster/cluster_client.go

@@ -17,7 +17,9 @@ limitations under the License.
 package cluster
 
 import (
+	"fmt"
 	"net"
+	"os"
 	"strings"
 
 	federation_v1alpha1 "k8s.io/kubernetes/federation/apis/federation/v1alpha1"
@@ -25,14 +27,17 @@ import (
 	"k8s.io/kubernetes/pkg/api/v1"
 	"k8s.io/kubernetes/pkg/client/restclient"
 	"k8s.io/kubernetes/pkg/client/typed/discovery"
+	client "k8s.io/kubernetes/pkg/client/unversioned"
 	"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
+	clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
 	utilnet "k8s.io/kubernetes/pkg/util/net"
 )
 
 const (
-	UserAgentName = "Cluster-Controller"
-	KubeAPIQPS    = 20.0
-	KubeAPIBurst  = 30
+	UserAgentName           = "Cluster-Controller"
+	KubeAPIQPS              = 20.0
+	KubeAPIBurst            = 30
+	KubeconfigSecretDataKey = "kubeconfig"
 )
 
 type ClusterClient struct {
@@ -59,7 +64,29 @@ func NewClusterClientSet(c *federation_v1alpha1.Cluster) (*ClusterClient, error)
 	}
 	var clusterClientSet = ClusterClient{}
 	if serverAddress != "" {
-		clusterConfig, err := clientcmd.BuildConfigFromFlags(serverAddress, "")
+		// Get a client to talk to the k8s apiserver, to fetch secrets from it.
+		client, err := client.NewInCluster()
+		if err != nil {
+			return nil, fmt.Errorf("error in creating in-cluster client: %s", err)
+		}
+		kubeconfigGetter := func() (*clientcmdapi.Config, error) {
+			// Get the namespace this is running in from the env variable.
+			namespace := os.Getenv("POD_NAMESPACE")
+			if namespace == "" {
+				return nil, fmt.Errorf("unexpected: POD_NAMESPACE env var returned empty string")
+			}
+			secret, err := client.Secrets(namespace).Get(c.Spec.SecretRef.Name)
+			if err != nil {
+				return nil, fmt.Errorf("error in fetching secret: %s", err)
+			}
+			data, ok := secret.Data[KubeconfigSecretDataKey]
+			if !ok {
+				return nil, fmt.Errorf("secret does not have data with key: %s", KubeconfigSecretDataKey)
+			}
+			return clientcmd.Load(data)
+		}
+
+		clusterConfig, err := clientcmd.BuildConfigFromKubeconfigGetter(serverAddress, kubeconfigGetter)
 		if err != nil {
 			return nil, err
 		}

pkg/client/unversioned/clientcmd/client_config.go

@@ -399,3 +399,12 @@ func BuildConfigFromFlags(masterUrl, kubeconfigPath string) (*restclient.Config,
 		&ClientConfigLoadingRules{ExplicitPath: kubeconfigPath},
 		&ConfigOverrides{ClusterInfo: clientcmdapi.Cluster{Server: masterUrl}}).ClientConfig()
 }
+
+// BuildConfigFromKubeconfigGetter is a helper function that builds configs from a master
+// url and a kubeconfigGetter.
+func BuildConfigFromKubeconfigGetter(masterUrl string, kubeconfigGetter KubeconfigGetter) (*restclient.Config, error) {
+	cc := NewNonInteractiveDeferredLoadingClientConfig(
+		&ClientConfigGetter{kubeconfigGetter: kubeconfigGetter},
+		&ConfigOverrides{ClusterInfo: clientcmdapi.Cluster{Server: masterUrl}})
+	return cc.ClientConfig()
+}

pkg/client/unversioned/clientcmd/loader.go

@@ -63,6 +63,40 @@ func currentMigrationRules() map[string]string {
 	return migrationRules
 }
 
+type ClientConfigLoader interface {
+	ConfigAccess
+	Load() (*clientcmdapi.Config, error)
+}
+
+type KubeconfigGetter func() (*clientcmdapi.Config, error)
+
+type ClientConfigGetter struct {
+	kubeconfigGetter KubeconfigGetter
+}
+
+// ClientConfigGetter implements the ClientConfigLoader interface.
+var _ ClientConfigLoader = &ClientConfigGetter{}
+
+func (g *ClientConfigGetter) Load() (*clientcmdapi.Config, error) {
+	return g.kubeconfigGetter()
+}
+
+func (g *ClientConfigGetter) GetLoadingPrecedence() []string {
+	return nil
+}
+func (g *ClientConfigGetter) GetStartingConfig() (*clientcmdapi.Config, error) {
+	return nil, nil
+}
+func (g *ClientConfigGetter) GetDefaultFilename() string {
+	return ""
+}
+func (g *ClientConfigGetter) IsExplicitFile() bool {
+	return false
+}
+func (g *ClientConfigGetter) GetExplicitFile() string {
+	return ""
+}
+
 // ClientConfigLoadingRules is an ExplicitPath and string slice of specific locations that are used for merging together a Config
 // Callers can put the chain together however they want, but we'd recommend:
 // EnvVarPathFiles if set (a list of files if set) OR the HomeDirectoryPath
@@ -80,6 +114,9 @@ type ClientConfigLoadingRules struct {
 	DoNotResolvePaths bool
 }
 
+// ClientConfigLoadingRules implements the ClientConfigLoader interface.
+var _ ClientConfigLoader = &ClientConfigLoadingRules{}
+
 // NewDefaultClientConfigLoadingRules returns a ClientConfigLoadingRules object with default fields filled in.  You are not required to
 // use this constructor
 func NewDefaultClientConfigLoadingRules() *ClientConfigLoadingRules {

pkg/client/unversioned/clientcmd/merged_client_builder.go

@@ -27,13 +27,13 @@ import (
 	clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
 )
 
-// DeferredLoadingClientConfig is a ClientConfig interface that is backed by a set of loading rules
+// DeferredLoadingClientConfig is a ClientConfig interface that is backed by a client config loader.
 // It is used in cases where the loading rules may change after you've instantiated them and you want to be sure that
 // the most recent rules are used.  This is useful in cases where you bind flags to loading rule parameters before
 // the parse happens and you want your calling code to be ignorant of how the values are being mutated to avoid
 // passing extraneous information down a call stack
 type DeferredLoadingClientConfig struct {
-	loadingRules   *ClientConfigLoadingRules
+	loader         ClientConfigLoader
 	overrides      *ConfigOverrides
 	fallbackReader io.Reader
 
@@ -42,13 +42,13 @@ type DeferredLoadingClientConfig struct {
 }
 
 // NewNonInteractiveDeferredLoadingClientConfig creates a ConfigClientClientConfig using the passed context name
-func NewNonInteractiveDeferredLoadingClientConfig(loadingRules *ClientConfigLoadingRules, overrides *ConfigOverrides) ClientConfig {
-	return &DeferredLoadingClientConfig{loadingRules: loadingRules, overrides: overrides}
+func NewNonInteractiveDeferredLoadingClientConfig(loader ClientConfigLoader, overrides *ConfigOverrides) ClientConfig {
+	return &DeferredLoadingClientConfig{loader: loader, 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: loadingRules, overrides: overrides, fallbackReader: fallbackReader}
+func NewInteractiveDeferredLoadingClientConfig(loader ClientConfigLoader, overrides *ConfigOverrides, fallbackReader io.Reader) ClientConfig {
+	return &DeferredLoadingClientConfig{loader: loader, overrides: overrides, fallbackReader: fallbackReader}
 }
 
 func (config *DeferredLoadingClientConfig) createClientConfig() (ClientConfig, error) {
@@ -57,16 +57,16 @@ func (config *DeferredLoadingClientConfig) createClientConfig() (ClientConfig, e
 		defer config.loadingLock.Unlock()
 
 		if config.clientConfig == nil {
-			mergedConfig, err := config.loadingRules.Load()
+			mergedConfig, err := config.loader.Load()
 			if err != nil {
 				return nil, err
 			}
 
 			var mergedClientConfig ClientConfig
 			if config.fallbackReader != nil {
-				mergedClientConfig = NewInteractiveClientConfig(*mergedConfig, config.overrides.CurrentContext, config.overrides, config.fallbackReader, config.loadingRules)
+				mergedClientConfig = NewInteractiveClientConfig(*mergedConfig, config.overrides.CurrentContext, config.overrides, config.fallbackReader, config.loader)
 			} else {
-				mergedClientConfig = NewNonInteractiveClientConfig(*mergedConfig, config.overrides.CurrentContext, config.overrides, config.loadingRules)
+				mergedClientConfig = NewNonInteractiveClientConfig(*mergedConfig, config.overrides.CurrentContext, config.overrides, config.loader)
 			}
 
 			config.clientConfig = mergedClientConfig
@@ -118,5 +118,5 @@ func (config *DeferredLoadingClientConfig) Namespace() (string, bool, error) {
 
 // ConfigAccess implements ClientConfig
 func (config *DeferredLoadingClientConfig) ConfigAccess() ConfigAccess {
-	return config.loadingRules
+	return config.loader
 }