This is a huge commit, it does following things:

1. refactor kubesphere dependency service client creation, we can
disable dependency by config
2. dependencies can be configured by configuration file
3. refactor cmd package using cobra.Command, so we can use hypersphere
to invoke command sepearately. Later we only need to build one image to
contains all kubesphere core components. One command to rule them all!
4. live reloading configuration currently not implemented

pkg/simple/client/k8s/options.go

@@ -0,0 +1,59 @@
+package k8s
+
+import (
+	"github.com/spf13/pflag"
+	"kubesphere.io/kubesphere/pkg/utils/reflectutils"
+	"os"
+)
+
+type KubernetesOptions struct {
+	// kubeconfig path, if not specified, will use
+	// in cluster way to create clientset
+	KubeConfig string `json:"kubeconfig" yaml:"kubeconfig"`
+
+	// kubernetes apiserver public address, used to generate kubeconfig
+	// for downloading, default to host defined in kubeconfig
+	// +optional
+	Master string `json:"master,omitempty" yaml:"master,omitempty"`
+
+	// kubernetes clientset qps
+	// +optional
+	QPS float32 `json:"qps,omitemtpy" yaml:"qps,omitempty"`
+
+	// kubernetes clientset burst
+	// +optional
+	Burst int `json:"burst,omitempty" yaml:"burst,omitempty"`
+}
+
+// NewKubernetesOptions returns a `zero` instance
+func NewKubernetesOptions() *KubernetesOptions {
+	return &KubernetesOptions{
+		KubeConfig: "",
+		QPS:        1e6,
+		Burst:      1e6,
+	}
+}
+
+func (k *KubernetesOptions) Validate() []error {
+	errors := []error{}
+
+	if k.KubeConfig != "" {
+		if _, err := os.Stat(k.KubeConfig); err != nil {
+			errors = append(errors, err)
+		}
+	}
+	return errors
+}
+
+func (k *KubernetesOptions) ApplyTo(options *KubernetesOptions) {
+	reflectutils.Override(options, k)
+}
+
+func (k *KubernetesOptions) AddFlags(fs *pflag.FlagSet) {
+	fs.StringVar(&k.KubeConfig, "kubeconfig", k.KubeConfig, ""+
+		"Path for kubernetes kubeconfig file, if left blank, will use "+
+		"in cluster way.")
+
+	fs.StringVar(&k.Master, "master", k.Master, ""+
+		"Used to generate kubeconfig for downloading, if not specified, will use host in kubeconfig.")
+}