Merge pull request kubernetes#61287 from deads2k/client-03-clientconfig

Automatic merge from submit-queue (batch tested with PRs 61644, 61624, 61743, 61019, 61287). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

provide easy methods for direct kubeconfig loading from bytes

Adds a `RESTConfigFromKubeConfig([]byte)` method for taking a kubeconfig and getting back the rest.Config.  There are ways to do this now, but it takes a fair amount of wiring that is a pain.

As kube starts dropping `--master` flags from its commands, it will be able to use this.  For current consumers, this will be a big simplification.

```release-note
NONE
```

Author: Kubernetes Submit Queue

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
 }