Add BackupConfiguration Controller (#671)

- [x]  Add `BackupConfiguration` Controller
- [x]  Ensure Sidecar and CronJob 
- [x] Ensure RBAC for CronJob
- [x] Create a CronJob which will create `BackupInstance` crd
- [x] Rename BackupInstance to BackupSession

Fixes:  stashed/stash#649

backup_session.go

@@ -0,0 +1,50 @@
+package cmds
+
+import (
+	"github.com/appscode/go/log"
+	cs "github.com/appscode/stash/client/clientset/versioned"
+	"github.com/appscode/stash/pkg/backupsession"
+	"github.com/spf13/cobra"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/clientcmd"
+	"kmodules.xyz/client-go/meta"
+)
+
+func NewBackupSession() *cobra.Command {
+	var (
+		masterURL      string
+		kubeconfigPath string
+
+		opt = backupsession.Options{
+			Namespace: meta.Namespace(),
+		}
+	)
+
+	cmd := &cobra.Command{
+		Use:               "backup-session",
+		Short:             "create a BackupSession",
+		DisableAutoGenTag: true,
+		Run: func(cmd *cobra.Command, args []string) {
+			config, err := clientcmd.BuildConfigFromFlags(masterURL, kubeconfigPath)
+			if err != nil {
+				log.Fatalf("Could not get Kubernetes config: %s", err)
+			}
+			kubeClient := kubernetes.NewForConfigOrDie(config)
+			stashClient := cs.NewForConfigOrDie(config)
+
+			ctrl := backupsession.New(kubeClient, stashClient, opt)
+			err = ctrl.CreateBackupSession()
+			if err != nil {
+				log.Fatal(err)
+			}
+
+		},
+	}
+
+	cmd.Flags().StringVar(&masterURL, "master", "", "The address of the Kubernetes API server (overrides any value in kubeconfig)")
+	cmd.Flags().StringVar(&kubeconfigPath, "kubeconfig", "", "Path to kubeconfig file with authorization information (the master location is set by the master flag).")
+	cmd.Flags().StringVar(&opt.Name, "backupsession.name", "", "Set BackupSession Name")
+	cmd.Flags().StringVar(&opt.Namespace, "backupsession.namespace", opt.Namespace, "Set BackupSession Namespace")
+
+	return cmd
+}

root.go

@@ -48,6 +48,7 @@ func NewRootCmd() *cobra.Command {
 	rootCmd.AddCommand(NewCmdScaleDown())
 	rootCmd.AddCommand(NewCmdSnapshots())
 	rootCmd.AddCommand(NewCmdForget())
+	rootCmd.AddCommand(NewBackupSession())
 
 	return rootCmd
 }