Make kubectl commands return errors and centralize exit handling

pkg/kubectl/cmd/rollingupdate.go

@@ -49,73 +49,8 @@ func (f *Factory) NewCmdRollingUpdate(out io.Writer) *cobra.Command {
 		Long:    rollingupdate_long,
 		Example: rollingupdate_example,
 		Run: func(cmd *cobra.Command, args []string) {
-			filename := util.GetFlagString(cmd, "filename")
-			if len(filename) == 0 {
-				usageError(cmd, "Must specify filename for new controller")
-			}
-			period := util.GetFlagDuration(cmd, "update-period")
-			interval := util.GetFlagDuration(cmd, "poll-interval")
-			timeout := util.GetFlagDuration(cmd, "timeout")
-			if len(args) != 1 {
-				usageError(cmd, "Must specify the controller to update")
-			}
-			oldName := args[0]
-			schema, err := f.Validator(cmd)
+			err := RunRollingUpdate(f, out, cmd, args)
 			util.CheckErr(err)
-
-			clientConfig, err := f.ClientConfig(cmd)
-			util.CheckErr(err)
-			cmdApiVersion := clientConfig.Version
-
-			mapper, typer := f.Object(cmd)
-			// TODO: use resource.Builder instead
-			mapping, namespace, newName, data := util.ResourceFromFile(filename, typer, mapper, schema, cmdApiVersion)
-			if mapping.Kind != "ReplicationController" {
-				usageError(cmd, "%s does not specify a valid ReplicationController", filename)
-			}
-			if oldName == newName {
-				usageError(cmd, "%s cannot have the same name as the existing ReplicationController %s",
-					filename, oldName)
-			}
-
-			cmdNamespace, err := f.DefaultNamespace(cmd)
-			util.CheckErr(err)
-			// TODO: use resource.Builder instead
-			err = util.CompareNamespace(cmdNamespace, namespace)
-			util.CheckErr(err)
-
-			client, err := f.Client(cmd)
-			util.CheckErr(err)
-
-			obj, err := mapping.Codec.Decode(data)
-			util.CheckErr(err)
-			newRc := obj.(*api.ReplicationController)
-
-			updater := kubectl.NewRollingUpdater(cmdNamespace, client)
-
-			// fetch rc
-			oldRc, err := client.ReplicationControllers(cmdNamespace).Get(oldName)
-			util.CheckErr(err)
-
-			var hasLabel bool
-			for key, oldValue := range oldRc.Spec.Selector {
-				if newValue, ok := newRc.Spec.Selector[key]; ok && newValue != oldValue {
-					hasLabel = true
-					break
-				}
-			}
-			if !hasLabel {
-				usageError(cmd, "%s must specify a matching key with non-equal value in Selector for %s",
-					filename, oldName)
-			}
-			// TODO: handle resizes during rolling update
-			if newRc.Spec.Replicas == 0 {
-				newRc.Spec.Replicas = oldRc.Spec.Replicas
-			}
-			err = updater.Update(out, oldRc, newRc, period, interval, timeout)
-			util.CheckErr(err)
-
-			fmt.Fprintf(out, "%s\n", newName)
 		},
 	}
 	cmd.Flags().String("update-period", updatePeriod, `Time to wait between updating pods. Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".`)
@@ -124,3 +59,93 @@ func (f *Factory) NewCmdRollingUpdate(out io.Writer) *cobra.Command {
 	cmd.Flags().StringP("filename", "f", "", "Filename or URL to file to use to create the new controller.")
 	return cmd
 }
+
+func RunRollingUpdate(f *Factory, out io.Writer, cmd *cobra.Command, args []string) error {
+	filename := util.GetFlagString(cmd, "filename")
+	if len(filename) == 0 {
+		return util.UsageError(cmd, "Must specify filename for new controller")
+	}
+	period := util.GetFlagDuration(cmd, "update-period")
+	interval := util.GetFlagDuration(cmd, "poll-interval")
+	timeout := util.GetFlagDuration(cmd, "timeout")
+	if len(args) != 1 {
+		return util.UsageError(cmd, "Must specify the controller to update")
+	}
+	oldName := args[0]
+	schema, err := f.Validator(cmd)
+	if err != nil {
+		return err
+	}
+
+	clientConfig, err := f.ClientConfig(cmd)
+	if err != nil {
+		return err
+	}
+	cmdApiVersion := clientConfig.Version
+
+	mapper, typer := f.Object(cmd)
+	// TODO: use resource.Builder instead
+	mapping, namespace, newName, data, err := util.ResourceFromFile(filename, typer, mapper, schema, cmdApiVersion)
+	if err != nil {
+		return err
+	}
+	if mapping.Kind != "ReplicationController" {
+		return util.UsageError(cmd, "%s does not specify a valid ReplicationController", filename)
+	}
+	if oldName == newName {
+		return util.UsageError(cmd, "%s cannot have the same name as the existing ReplicationController %s",
+			filename, oldName)
+	}
+
+	cmdNamespace, err := f.DefaultNamespace(cmd)
+	if err != nil {
+		return err
+	}
+	// TODO: use resource.Builder instead
+	err = util.CompareNamespace(cmdNamespace, namespace)
+	if err != nil {
+		return err
+	}
+
+	client, err := f.Client(cmd)
+	if err != nil {
+		return err
+	}
+
+	obj, err := mapping.Codec.Decode(data)
+	if err != nil {
+		return err
+	}
+	newRc := obj.(*api.ReplicationController)
+
+	updater := kubectl.NewRollingUpdater(cmdNamespace, client)
+
+	// fetch rc
+	oldRc, err := client.ReplicationControllers(cmdNamespace).Get(oldName)
+	if err != nil {
+		return err
+	}
+
+	var hasLabel bool
+	for key, oldValue := range oldRc.Spec.Selector {
+		if newValue, ok := newRc.Spec.Selector[key]; ok && newValue != oldValue {
+			hasLabel = true
+			break
+		}
+	}
+	if !hasLabel {
+		return util.UsageError(cmd, "%s must specify a matching key with non-equal value in Selector for %s",
+			filename, oldName)
+	}
+	// TODO: handle resizes during rolling update
+	if newRc.Spec.Replicas == 0 {
+		newRc.Spec.Replicas = oldRc.Spec.Replicas
+	}
+	err = updater.Update(out, oldRc, newRc, period, interval, timeout)
+	if err != nil {
+		return err
+	}
+
+	fmt.Fprintf(out, "%s\n", newName)
+	return nil
+}