add cli plugin example repo

staging/src/BUILD

@@ -211,6 +211,8 @@ filegroup(
         "//staging/src/k8s.io/metrics/pkg/client/custom_metrics:all-srcs",
         "//staging/src/k8s.io/metrics/pkg/client/external_metrics:all-srcs",
         "//staging/src/k8s.io/sample-apiserver:all-srcs",
+        "//staging/src/k8s.io/sample-cli-plugin/cmd:all-srcs",
+        "//staging/src/k8s.io/sample-cli-plugin/pkg/cmd:all-srcs",
         "//staging/src/k8s.io/sample-controller:all-srcs",
     ],
     tags = ["automanaged"],

staging/src/k8s.io/sample-cli-plugin/CONTRIBUTING.md

+# Contributing guidelines
+
+Do not open pull requests directly against this repository, they will be ignored. Instead, please open pull requests against [kubernetes/kubernetes](https://git.k8s.io/kubernetes/).  Please follow the same [contributing guide](https://git.k8s.io/kubernetes/CONTRIBUTING.md) you would follow for any other pull request made to kubernetes/kubernetes.
+
+This repository is published from [kubernetes/kubernetes/staging/src/k8s.io/sample-cli-plugin](https://git.k8s.io/kubernetes/staging/src/k8s.io/sample-cli-plugin) by the [kubernetes publishing-bot](https://git.k8s.io/publishing-bot).
+
+Please see [Staging Directory and Publishing](https://git.k8s.io/community/contributors/devel/staging.md) for more information

staging/src/k8s.io/sample-cli-plugin/Godeps/OWNERS

+approvers:
+- juanvallejo
+- soltysh

staging/src/k8s.io/sample-cli-plugin/Godeps/Readme

+This directory tree is generated automatically by godep.
+
+Please do not edit.
+
+See https://github.com/tools/godep for more information.

staging/src/k8s.io/sample-cli-plugin/OWNERS

+approvers:
+- juanvallejo
+- soltysh
+reviewers:
+- seans3
+- deads2k
+- soltysh
+- juanvallejo
+labels:
+- sig/cli

staging/src/k8s.io/sample-cli-plugin/README.md

+# sample-cli-plugin
+
+This repository implements a single kubectl plugin for switching the namespace
+that the current KUBECONFIG context points to. In order to remain as indestructive
+as possible, no existing contexts are modified.
+
+**Note:** go-get or vendor this package as `k8s.io/sample-cli-plugin`.
+
+This particular example demonstrates how to perform basic operations such as:
+
+* How to create a new custom command that follows kubectl patterns
+* How to obtain a user's KUBECONFIG settings and modify them
+* How to make general use of the provided "cli-runtime" set of helpers for kubectl and third-party plugins
+
+It makes use of the genericclioptions in [k8s.io/cli-runtime](https://github.com/kubernetes/cli-runtime)
+to generate a set of configuration flags which are in turn used to generate a raw representation of
+the user's KUBECONFIG, as well as to obtain configuration which can be used with RESTClients when sending
+requests to a kubernetes api server.
+
+## Details
+
+The sample cli plugin uses the [client-go library](https://github.com/kubernetes/client-go/tree/master/tools/clientcmd) to patch an existing KUBECONFIG file in a user's environment in order to update context information to point the client to a new or existing namespace.
+
+In order to be as non-destructive as possible, no existing contexts are modified in any way. Rather, the current context is examined, and matched against existing contexts to find a context containing the same "AuthInfo" and "Cluster" information, but with the newly desired namespace requested by the user.
+
+## Purpose
+
+This is an example of how to build a kubectl plugin using the same set of tools and helpers available to kubectl.
+
+## Running
+
+```sh
+# assumes you have a working KUBECONFIG
+$ go build cmd/kubectl-ns.go
+# place the built binary somewhere in your PATH
+$ cp ./kubectl-ns /usr/local/bin
+
+# you can now begin using this plugin as a regular kubectl command:
+# update your configuration to point to "new-namespace"
+$ kubectl ns new-namespace
+# any kubectl commands you perform from now on will use "new-namespace"
+$ kubectl get pod
+NAME                READY     STATUS    RESTARTS   AGE
+new-namespace-pod   1/1       Running   0          1h
+
+# list all of the namespace in use by contexts in your KUBECONFIG
+$ kubectl ns --list
+
+# show the namespace that the currently set context in your KUBECONFIG points to
+$ kubectl ns
+```
+
+## Use Cases
+
+This plugin can be used as a developer tool, in order to quickly view or change the current namespace
+that kubectl points to.
+
+It can also be used as a means of showcasing usage of the cli-runtime set of utilities to aid in
+third-party plugin development.
+
+## Cleanup
+
+You can "uninstall" this plugin from kubectl by simply removing it from your PATH:
+
+    $ rm /usr/local/bin/kubectl-ns
+
+## Compatibility
+
+HEAD of this repository will match HEAD of k8s.io/apimachinery and
+k8s.io/client-go.
+
+## Where does it come from?
+
+`sample-cli-plugin` is synced from
+https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/sample-cli-plugin.
+Code changes are made in that location, merged into k8s.io/kubernetes and
+later synced here.

staging/src/k8s.io/sample-cli-plugin/SECURITY_CONTACTS

+# Defined below are the security contacts for this repo.
+#
+# They are the contact point for the Product Security Team to reach out
+# to for triaging and handling of incoming issues.
+#
+# The below names agree to abide by the
+# [Embargo Policy](https://github.com/kubernetes/sig-release/blob/master/security-release-process-documentation/security-release-process.md#embargo-policy)
+# and will be removed and replaced if they violate that agreement.
+#
+# DO NOT REPORT SECURITY VULNERABILITIES DIRECTLY TO THESE NAMES, FOLLOW THE
+# INSTRUCTIONS AT https://kubernetes.io/security/
+
+cjcullen
+jessfraz
+liggitt
+philips
+tallclair

staging/src/k8s.io/sample-cli-plugin/cmd/BUILD

+load("@io_bazel_rules_go//go:def.bzl", "go_binary", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["kubectl-ns.go"],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/sample-cli-plugin/cmd",
+    importpath = "k8s.io/sample-cli-plugin/cmd",
+    visibility = ["//visibility:private"],
+    deps = [
+        "//staging/src/k8s.io/cli-runtime/pkg/genericclioptions:go_default_library",
+        "//staging/src/k8s.io/sample-cli-plugin/pkg/cmd:go_default_library",
+        "//vendor/github.com/spf13/pflag:go_default_library",
+    ],
+)
+
+go_binary(
+    name = "cmd",
+    embed = [":go_default_library"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

staging/src/k8s.io/sample-cli-plugin/cmd/kubectl-ns.go

+package main
+
+import (
+	"os"
+
+	"github.com/spf13/pflag"
+
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/sample-cli-plugin/pkg/cmd"
+)
+
+func main() {
+	flags := pflag.NewFlagSet("kubectl-ns", pflag.ExitOnError)
+	pflag.CommandLine = flags
+
+	root := cmd.NewCmdNamespace(genericclioptions.IOStreams{In: os.Stdin, Out: os.Stdout, ErrOut: os.Stderr})
+	if err := root.Execute(); err != nil {
+		os.Exit(1)
+	}
+}

staging/src/k8s.io/sample-cli-plugin/pkg/cmd/BUILD

+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["ns.go"],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/sample-cli-plugin/pkg/cmd",
+    importpath = "k8s.io/sample-cli-plugin/pkg/cmd",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//staging/src/k8s.io/cli-runtime/pkg/genericclioptions:go_default_library",
+        "//staging/src/k8s.io/client-go/tools/clientcmd:go_default_library",
+        "//staging/src/k8s.io/client-go/tools/clientcmd/api:go_default_library",
+        "//vendor/github.com/spf13/cobra:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

staging/src/k8s.io/sample-cli-plugin/pkg/cmd/ns.go

+package cmd
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/client-go/tools/clientcmd/api"
+
+	"k8s.io/cli-runtime/pkg/genericclioptions"
+)
+
+var (
+	namespace_example = `
+	# view the current namespace in your KUBECONFIG
+	%[1]s ns
+
+	# view all of the namespaces in use by contexts in your KUBECONFIG
+	%[1] ns --list
+
+	# switch your current-context to one that contains the desired namespace
+	%[1]s ns foo
+`
+)
+
+type NamespaceOptions struct {
+	configFlags *genericclioptions.ConfigFlags
+
+	rawConfig      api.Config
+	listNamespaces bool
+	args           []string
+
+	genericclioptions.IOStreams
+}
+
+func NewNamespaceOptions(streams genericclioptions.IOStreams) *NamespaceOptions {
+	return &NamespaceOptions{
+		configFlags: genericclioptions.NewConfigFlags(),
+
+		IOStreams: streams,
+	}
+}
+
+func NewCmdNamespace(streams genericclioptions.IOStreams) *cobra.Command {
+	o := NewNamespaceOptions(streams)
+
+	cmd := &cobra.Command{
+		Use:          "ns [new-namespace] [flags]",
+		Short:        "View or set the current namespace",
+		Example:      namespace_example,
+		SilenceUsage: true,
+		RunE: func(c *cobra.Command, args []string) error {
+			if err := o.Complete(args); err != nil {
+				return err
+			}
+			if err := o.Validate(); err != nil {
+				return err
+			}
+			if err := o.Run(); err != nil {
+				return err
+			}
+
+			return nil
+		},
+	}
+
+	cmd.Flags().BoolVar(&o.listNamespaces, "list", o.listNamespaces, "if true, print the list of all namespaces in the current KUBECONFIG")
+	o.configFlags.AddFlags(cmd.Flags())
+
+	return cmd
+}
+
+func (o *NamespaceOptions) Complete(args []string) error {
+	var err error
+	o.rawConfig, err = o.configFlags.ToRawKubeConfigLoader().RawConfig()
+	if err != nil {
+		return err
+	}
+
+	o.args = args
+	return nil
+}
+
+func (o *NamespaceOptions) Validate() error {
+	if len(o.rawConfig.CurrentContext) == 0 {
+		return fmt.Errorf("no context is currently set in your configuration")
+	}
+	if len(o.args) > 1 {
+		return fmt.Errorf("either one or no arguments are allowed")
+	}
+
+	return nil
+}
+
+func (o *NamespaceOptions) Run() error {
+	if len(o.args) > 0 && len(o.args[0]) > 0 {
+		return o.setNamespace(o.args[0])
+	}
+
+	namespaces := map[string]bool{}
+
+	for name, c := range o.rawConfig.Contexts {
+		if !o.listNamespaces && name == o.rawConfig.CurrentContext {
+			if len(c.Namespace) == 0 {
+				return fmt.Errorf("no namespace is set for your current context: %q", name)
+			}
+
+			fmt.Fprintf(o.Out, "%s\n", c.Namespace)
+			return nil
+		}
+
+		// skip if dealing with a namespace we have already seen
+		// or if the namespace for the current context is empty
+		if len(c.Namespace) == 0 {
+			continue
+		}
+		if namespaces[c.Namespace] {
+			continue
+		}
+
+		namespaces[c.Namespace] = true
+	}
+
+	if !o.listNamespaces {
+		return fmt.Errorf("unable to find information for the current namespace in your configuration")
+	}
+
+	for n := range namespaces {
+		fmt.Fprintf(o.Out, "%s\n", n)
+	}
+
+	return nil
+}
+
+func (o *NamespaceOptions) setNamespace(newNamespace string) error {
+	if len(newNamespace) == 0 {
+		return fmt.Errorf("a non-empty namespace must be provided")
+	}
+
+	existingCtx, ok := o.rawConfig.Contexts[o.rawConfig.CurrentContext]
+	if !ok {
+		return fmt.Errorf("unable to gather information about the current context")
+	}
+
+	if existingCtx.Namespace == newNamespace {
+		fmt.Fprintf(o.Out, "already using namespace %q\n", newNamespace)
+		return nil
+	}
+
+	// determine if a context exists for the new namespace
+	existingCtxName := ""
+	for name, c := range o.rawConfig.Contexts {
+		if c.Namespace != newNamespace || c.Cluster != existingCtx.Cluster || c.AuthInfo != existingCtx.AuthInfo {
+			continue
+		}
+
+		existingCtxName = name
+		break
+	}
+
+	if len(existingCtxName) == 0 {
+		newCtx := api.NewContext()
+		newCtx.AuthInfo = existingCtx.AuthInfo
+		newCtx.Cluster = existingCtx.Cluster
+		newCtx.Namespace = newNamespace
+
+		newCtxName := newNamespace
+		if len(existingCtx.Cluster) > 0 {
+			newCtxName = fmt.Sprintf("%s/%s", newCtxName, existingCtx.Cluster)
+		}
+		if len(existingCtx.AuthInfo) > 0 {
+			cleanAuthInfo := strings.Split(existingCtx.AuthInfo, "/")[0]
+			newCtxName = fmt.Sprintf("%s/%s", newCtxName, cleanAuthInfo)
+		}
+
+		o.rawConfig.Contexts[newCtxName] = newCtx
+		existingCtxName = newCtxName
+	}
+
+	configAccess := clientcmd.NewDefaultPathOptions()
+	o.rawConfig.CurrentContext = existingCtxName
+
+	if err := clientcmd.ModifyConfig(configAccess, o.rawConfig, true); err != nil {
+		return err
+	}
+
+	fmt.Fprintf(o.Out, "namespace changed to %q\n", newNamespace)
+	return nil
+}

vendor/k8s.io/sample-cli-plugin

+../../staging/src/k8s.io/sample-cli-plugin
\ No newline at end of file