feat(kubens): added force flag to switch namespaces even if it doesn't exist

README.md

@@ -46,6 +46,15 @@ Active namespace is "kube-system".
 $ kubens -
 Context "test" set.
 Active namespace is "default".
+
+# change the active namespace even if it doesn't exist
+$ kubens not-found-namespace --force
+Context "test" set.
+Active namespace is "not-found-namespace".
+---
+$ kubens not-found-namespace --f
+Context "test" set.
+Active namespace is "not-found-namespace".
 ```
 
 If you have [`fzf`](https://github.com/junegunn/fzf) installed, you can also

cmd/kubens/flags.go

@@ -33,15 +33,23 @@ func (op UnsupportedOp) Run(_, _ io.Writer) error {
 // parseArgs looks at flags (excl. executable name, i.e. argv[0])
 // and decides which operation should be taken.
 func parseArgs(argv []string) Op {
-	if len(argv) == 0 {
+	n := len(argv)
+
+	if n == 0 {
 		if cmdutil.IsInteractiveMode(os.Stdout) {
 			return InteractiveSwitchOp{SelfCmd: os.Args[0]}
 		}
 		return ListOp{}
 	}
 
-	if len(argv) == 1 {
+	if n == 1 || n == 2 {
 		v := argv[0]
+		force := false
+
+		if n == 2 {
+			force = argv[1] == "--force" || argv[1] == "-f"
+		}
+
 		if v == "--help" || v == "-h" {
 			return HelpOp{}
 		}
@@ -54,7 +62,7 @@ func parseArgs(argv []string) Op {
 		if strings.HasPrefix(v, "-") && v != "-" {
 			return UnsupportedOp{Err: fmt.Errorf("unsupported option '%s'", v)}
 		}
-		return SwitchOp{Target: argv[0]}
+		return SwitchOp{Target: argv[0], Force: force}
 	}
 	return UnsupportedOp{Err: fmt.Errorf("too many arguments")}
 }

cmd/kubens/fzf.go

@@ -65,7 +65,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 	if choice == "" {
 		return errors.New("you did not choose any of the options")
 	}
-	name, err := switchNamespace(kc, choice)
+	name, err := switchNamespace(kc, choice, false)
 	if err != nil {
 		return errors.Wrap(err, "failed to switch namespace")
 	}

cmd/kubens/help.go

@@ -35,6 +35,8 @@ func printUsage(out io.Writer) error {
 	help := `USAGE:
   %PROG%                    : list the namespaces in the current context
   %PROG% <NAME>             : change the active namespace of current context
+  %PROG% <NAME> --force     : force change the active namespace of current context (even if it doesn't exist)
+  %PROG% <NAME> --f     : force change the active namespace of current context (even if it doesn't exist)
   %PROG% -                  : switch to the previous namespace in this context
   %PROG% -c, --current      : show the current namespace
   %PROG% -h,--help          : show this message

cmd/kubens/switch.go

@@ -29,6 +29,7 @@ import (
 
 type SwitchOp struct {
 	Target string // '-' for back and forth, or NAME
+	Force  bool   // force switch even if the namespace doesn't exist
 }
 
 func (s SwitchOp) Run(_, stderr io.Writer) error {
@@ -38,7 +39,7 @@ func (s SwitchOp) Run(_, stderr io.Writer) error {
 		return errors.Wrap(err, "kubeconfig error")
 	}
 
-	toNS, err := switchNamespace(kc, s.Target)
+	toNS, err := switchNamespace(kc, s.Target, s.Force)
 	if err != nil {
 		return err
 	}
@@ -46,7 +47,7 @@ func (s SwitchOp) Run(_, stderr io.Writer) error {
 	return err
 }
 
-func switchNamespace(kc *kubeconfig.Kubeconfig, ns string) (string, error) {
+func switchNamespace(kc *kubeconfig.Kubeconfig, ns string, force bool) (string, error) {
 	ctx := kc.GetCurrentContext()
 	if ctx == "" {
 		return "", errors.New("current-context is not set")
@@ -69,12 +70,14 @@ func switchNamespace(kc *kubeconfig.Kubeconfig, ns string) (string, error) {
 		ns = prev
 	}
 
-	ok, err := namespaceExists(kc, ns)
-	if err != nil {
-		return "", errors.Wrap(err, "failed to query if namespace exists (is cluster accessible?)")
-	}
-	if !ok {
-		return "", errors.Errorf("no namespace exists with name \"%s\"", ns)
+	if !force {
+		ok, err := namespaceExists(kc, ns)
+		if err != nil {
+			return "", errors.Wrap(err, "failed to query if namespace exists (is cluster accessible?)")
+		}
+		if !ok {
+			return "", errors.Errorf("no namespace exists with name \"%s\"", ns)
+		}
 	}
 
 	if err := kc.SetNamespace(ctx, ns); err != nil {