Merge pull request kubernetes#18956 from deads2k/up-21-componentinstall

Automatic merge from submit-queue.

 make registry installation a component

Demonstrate a simple way of making a component and installing it.  This builds on previous pulls and shows how we can start define an interface.

I think after we switch pieces over, we'll find points of commonality as their entry points.  I suspect they will include:
 1. cluster-admin.kubeconfig
 2. docker helper? We should try to switch this to actually installing with pods.
 3. uninstall API.  Something to remove it anyway.
 4. idempotent.  We will call it *on every cluster up*

/assign @mfojtik
/assign @soltysh

Origin-commit: eb016b358623b0d6c672ba1c3cfcfa1b20f1970b

Author: k8s-publishing-bot

staging/src/k8s.io/client-go/tools/clientcmd/client_config.go

@@ -100,6 +100,26 @@ func NewInteractiveClientConfig(config clientcmdapi.Config, contextName string,
 	return &DirectClientConfig{config, contextName, overrides, fallbackReader, configAccess, promptedCredentials{}}
 }
 
+// NewClientConfigFromBytes takes your kubeconfig and gives you back a ClientConfig
+func NewClientConfigFromBytes(configBytes []byte) (ClientConfig, error) {
+	config, err := Load(configBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	return &DirectClientConfig{*config, "", &ConfigOverrides{}, nil, nil, promptedCredentials{}}, nil
+}
+
+// RESTConfigFromKubeConfig is a convenience method to give back a restconfig from your kubeconfig bytes.
+// For programmatic access, this is what you want 80% of the time
+func RESTConfigFromKubeConfig(configBytes []byte) (*restclient.Config, error) {
+	clientConfig, err := NewClientConfigFromBytes(configBytes)
+	if err != nil {
+		return nil, err
+	}
+	return clientConfig.ClientConfig()
+}
+
 func (config *DirectClientConfig) RawConfig() (clientcmdapi.Config, error) {
 	return config.config, nil
 }