Add support for -c/--current

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

cmd/kubectx/current.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pkg/errors"
+)
+
+func printCurrentContext(w io.Writer) error {
+	cfgPath, err := kubeconfigPath()
+	if err != nil {
+		return errors.Wrap(err, "failed to determine kubeconfig path")
+	}
+
+	cfg, err := parseKubeconfig(cfgPath)
+	if err != nil {
+		return errors.Wrap(err, "failed to read kubeconfig file")
+	}
+
+	v := cfg.CurrentContext
+	if v == "" {
+		return errors.New("current-context is not set")
+	}
+	_, err = fmt.Fprintln(w, v)
+	return err
+}

cmd/kubectx/flags.go

@@ -10,6 +10,9 @@ type HelpOp struct{}
 // ListOp describes listing contexts.
 type ListOp struct{}
 
+// CurrentOp prints the current context
+type CurrentOp struct{}
+
 // SwitchOp indicates intention to switch contexts.
 type SwitchOp struct {
 	Target string // '-' for back and forth, or NAME
@@ -30,6 +33,9 @@ func parseArgs(argv []string) Op {
 		if v == "--help" || v == "-h" {
 			return HelpOp{}
 		}
+		if v == "--current" || v == "-c" {
+			return CurrentOp{}
+		}
 
 		if strings.HasPrefix(v, "-") && v != "-" {
 			return UnknownOp{argv}

cmd/kubectx/flags_test.go

@@ -24,6 +24,12 @@ func Test_parseArgs_new(t *testing.T) {
 		{name: "help long form",
 			args: []string{"--help"},
 			want: HelpOp{}},
+		{name: "current shorthand",
+			args: []string{"-c"},
+			want: CurrentOp{}},
+		{name: "current long form",
+			args: []string{"--current"},
+			want: CurrentOp{}},
 		{name: "switch by name",
 			args: []string{"foo"},
 			want: SwitchOp{Target: "foo"}},

cmd/kubectx/list.go

@@ -31,7 +31,6 @@ func printListContexts(out io.Writer) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to read kubeconfig file")
 	}
-	_ = cfg
 
 	ctxs := make([]string, 0, len(cfg.Contexts))
 	for _, c := range cfg.Contexts {

cmd/kubectx/main.go

@@ -17,8 +17,16 @@ func main() {
 	switch v := op.(type) {
 	case HelpOp:
 		printHelp(os.Stdout)
+	case CurrentOp:
+		if err := printCurrentContext(os.Stdout); err != nil {
+			printError(err.Error())
+			os.Exit(1)
+		}
 	case ListOp:
-		printListContexts(os.Stdout)
+		if err := printListContexts(os.Stdout); err != nil {
+			printError(err.Error())
+			os.Exit(1)
+		}
 	case SwitchOp:
 		var newCtx string
 		var err error