plugin feature

README.md

@@ -185,3 +185,29 @@ Establish an SSH connection to a Shoot cluster's node.
 ```bash
 gardenctl ssh my-node
 ```
+### Plugins
+To use [plugins](https://pkg.go.dev/plugin) , you have to make a `plugins` directory under `.garden`, and place the plugin files(with a .so extension) within that directory.
+
+example plugin, 
+```
+package main
+
+import (
+	"fmt"
+	"github.com/spf13/cobra"
+)
+
+var NewCmd = &cobra.Command{  //must be `NewCmd` name
+	Use:   "example",
+	Short: "A brief description of your command ",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Println("Test called")
+	},
+}
+
+```
+
+build plugin `.so` file
+```
+go build -buildmode=plugin
+```

internal/gen/markdown.go

@@ -29,6 +29,13 @@ func main() {
 		outDir = "./docs/help"
 	}
 
+	for _, c := range gardenctl.Commands() {
+		_, ok := c.Annotations["plugins"]
+		if ok {
+			gardenctl.RemoveCommand(c)
+		}
+	}
+
 	err := doc.GenMarkdownTree(gardenctl, outDir)
 	if err != nil {
 		log.Fatal(err)

pkg/cmd/cmd.go

@@ -29,6 +29,7 @@ import (
 	cmdsshpatch "github.com/gardener/gardenctl-v2/pkg/cmd/sshpatch"
 	cmdtarget "github.com/gardener/gardenctl-v2/pkg/cmd/target"
 	cmdversion "github.com/gardener/gardenctl-v2/pkg/cmd/version"
+	"github.com/gardener/gardenctl-v2/pkg/plugins"
 )
 
 const (
@@ -124,6 +125,15 @@ Find more information at: https://github.com/gardener/gardenctl-v2/blob/master/R
 	cmd.AddCommand(cmdrc.NewCmdRC(f, ioStreams))
 	cmd.AddCommand(kubeconfig.NewCmdKubeconfig(f, ioStreams))
 
+	for _, c := range plugins.Load() {
+		_, ok := c.Annotations["plugins"]
+		if !ok {
+			c.Annotations = map[string]string{"plugins": "yes"}
+		}
+
+		cmd.AddCommand(c)
+	}
+
 	return cmd
 }
 

pkg/plugins/plugins.go

@@ -0,0 +1,94 @@
+/*
+SPDX-FileCopyrightText: 2023 SAP SE or an SAP affiliate company and Gardener contributors
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package plugins
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"plugin"
+
+	"github.com/mitchellh/go-homedir"
+	"github.com/spf13/cobra"
+)
+
+const (
+	gardenHomeFolder = ".garden"
+	pluginsFolder    = "plugins"
+)
+
+func LoadPlugins(pluginPath string) ([]*cobra.Command, error) {
+	plugins := []string{}
+
+	var b plugin.Symbol
+
+	var cmds []*cobra.Command
+
+	files, err := os.ReadDir(pluginPath)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, file := range files {
+		filePath := filepath.Join(pluginPath, file.Name())
+		ext := path.Ext(filePath)
+
+		if ext == ".so" {
+			plugins = append(plugins, filePath)
+		}
+	}
+
+	if len(plugins) == 0 {
+		return nil, nil
+	}
+
+	for _, item := range plugins {
+		p, err := plugin.Open(item)
+		if err != nil {
+			return nil, fmt.Errorf("plugin open error or invalid file %w", err)
+		}
+
+		b, err = p.Lookup("NewCmd")
+		if err != nil {
+			return nil, fmt.Errorf("plugin cmd name not found %w", err)
+		}
+
+		_, ok := b.(**cobra.Command)
+		if !ok {
+			return nil, fmt.Errorf("type assertion error")
+		}
+
+		cmds = append(cmds, *b.(**cobra.Command))
+	}
+
+	return cmds, nil
+}
+
+func Load() []*cobra.Command {
+	var cmds []*cobra.Command
+
+	home, err := homedir.Dir()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "Plugins Error:", err)
+	}
+
+	pluginsPath := filepath.Join(home, gardenHomeFolder, pluginsFolder)
+
+	if _, err := os.Stat(pluginsPath); err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+	} else {
+		cmds, err = LoadPlugins(pluginsPath)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "Plugins Error:", err)
+		}
+	}
+
+	return cmds
+}

pkg/plugins/plugins_test.go

@@ -0,0 +1,38 @@
+/*
+SPDX-FileCopyrightText: 2023 SAP SE or an SAP affiliate company and Gardener contributors
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package plugins_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/gardener/gardenctl-v2/pkg/plugins"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestPlugins(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Plugins Package Test Suite")
+}
+
+var _ = Describe("plugins", func() {
+	It("should return an error when plugins loading fake example.so", func() {
+		pluginsPath, err := os.MkdirTemp("", "plugins")
+		Expect(err).NotTo(HaveOccurred())
+
+		filename := filepath.Join(pluginsPath, "example.so")
+		_, err = os.Create(filename)
+		Expect(err).NotTo(HaveOccurred())
+
+		_, err = plugins.LoadPlugins(pluginsPath)
+		Expect(err).To(MatchError(MatchRegexp("^plugin open error or invalid file ")))
+		Expect(os.RemoveAll(pluginsPath)).To(Succeed())
+	})
+})