348: initial impl for unsetting kubens

cmd/kubens/flags.go

@@ -51,6 +51,9 @@ func parseArgs(argv []string) Op {
 		if v == "--current" || v == "-c" {
 			return CurrentOp{}
 		}
+		if v == "--unset" || v == "-u" {
+			return UnsetOp{}
+		}
 		if strings.HasPrefix(v, "-") && v != "-" {
 			return UnsupportedOp{Err: fmt.Errorf("unsupported option '%s'", v)}
 		}

cmd/kubens/unset.go

@@ -0,0 +1,48 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"io"
+
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
+	"github.com/pkg/errors"
+)
+
+// UnsetOp indicates intention to remove current namespace preference.
+type UnsetOp struct{}
+
+func (u UnsetOp) Run(_, stderr io.Writer) error {
+	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
+	defer kc.Close()
+	if err := kc.Parse(); err != nil {
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	ctx := kc.GetCurrentContext()
+	if ctx == "" {
+		return errors.New("current-context is not set")
+	}
+	err := kc.UnsetNamespace(ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not unset namespace for the current-context")
+	}
+	if err := kc.Save(); err != nil {
+		return errors.Wrap(err, "failed to save kubeconfig file")
+	}
+
+	err = printer.Success(stderr, "Active namespace is unset")
+	return err
+}

internal/kubeconfig/namespace.go

@@ -14,7 +14,11 @@
 
 package kubeconfig
 
-import "gopkg.in/yaml.v3"
+import (
+	"errors"
+
+	"gopkg.in/yaml.v3"
+)
 
 const (
 	defaultNamespace = "default"
@@ -75,3 +79,31 @@ func (k *Kubeconfig) SetNamespace(ctxName string, ns string) error {
 	}
 	return nil
 }
+
+func (k *Kubeconfig) UnsetNamespace(ctxName string) error {
+	ctxNode, err := k.contextNode(ctxName)
+	if err != nil {
+		return err
+	}
+
+	ctxBodyNode := valueOf(ctxNode, "context")
+	if ctxBodyNode == nil {
+		return errors.New("invalid context key")
+	}
+
+	newKVParis := []*yaml.Node{}
+	if ctxBodyNode.Kind == yaml.MappingNode {
+		for i := 0; i < len(ctxBodyNode.Content); i++ {
+			ch := ctxBodyNode.Content[i]
+			if ch.Kind == yaml.ScalarNode && ch.Value == "namespace" {
+				// Skip the value belonging to `namespace` key
+				i++
+				continue
+			}
+			newKVParis = append(newKVParis, ch)
+		}
+	}
+
+	ctxBodyNode.Content = newKVParis
+	return nil
+}