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/mysql/options.go

@@ -0,0 +1,43 @@
+package mysql
+
+import (
+	"github.com/spf13/pflag"
+	reflectutils "kubesphere.io/kubesphere/pkg/utils/reflectutils"
+	"time"
+)
+
+type MySQLOptions struct {
+	Host                  string        `json:"host,omitempty" yaml:"host,omitempty" description:"MySQL service host address"`
+	Username              string        `json:"username,omitempty" yaml:"username,omitempty"`
+	Password              string        `json:"-" yaml:"password,omitempty"`
+	MaxIdleConnections    int           `json:"maxIdleConnections,omitempty" yaml:"maxIdleConnections,omitempty"`
+	MaxOpenConnections    int           `json:"maxOpenConnections,omitempty" yaml:"maxOpenConnections,omitempty"`
+	MaxConnectionLifeTime time.Duration `json:"maxConnectionLifeTime,omitempty" yaml:"maxConnectionLifeTime,omitempty"`
+}
+
+// NewMySQLOptions create a `zero` value instance
+func NewMySQLOptions() *MySQLOptions {
+	return &MySQLOptions{}
+}
+
+func (m *MySQLOptions) Validate() []error {
+	errors := []error{}
+
+	return errors
+}
+
+func (m *MySQLOptions) ApplyTo(options *MySQLOptions) {
+	reflectutils.Override(options, m)
+}
+
+func (m *MySQLOptions) AddFlags(fs *pflag.FlagSet) {
+
+	fs.StringVar(&m.Host, "mysql-host", m.Host, ""+
+		"MySQL service host address. If left blank, following options will be ignored.")
+
+	fs.StringVar(&m.Username, "mysql-username", m.Username, ""+
+		"Username for access to mysql service.")
+
+	fs.StringVar(&m.Password, "mysql-password", m.Password, ""+
+		"Password for access to mysql, should be used pair with password.")
+}