Move list merge into plugin manager

cmd/kn/main.go

@@ -25,8 +25,6 @@ import (
 	"knative.dev/client/pkg/kn/config"
 	"knative.dev/client/pkg/kn/plugin"
 	"knative.dev/client/pkg/kn/root"
-
-	pkgplugin "knative.dev/client-pkg/pkg/kn/plugin"
 )
 
 func main() {
@@ -64,11 +62,6 @@ func run(args []string) error {
 
 	pluginManager := plugin.NewManager(config.GlobalConfig.PluginsDir(), config.GlobalConfig.LookupPluginsInPath())
 
-	// Merge plugins that implements client-pkg Plugin type to the same manager instance
-	for _, p := range pkgplugin.InternalPlugins {
-		pluginManager.AppendPlugin(p)
-	}
-
 	// Create kn root command and all sub-commands
 	rootCmd, err := root.NewRootCommand(pluginManager.HelpTemplateFuncs())
 	if err != nil {

pkg/kn/plugin/manager.go

@@ -17,6 +17,7 @@ package plugin
 import (
 	"errors"
 	"fmt"
+	pkgplugin "knative.dev/client-pkg/pkg/kn/plugin"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -32,6 +33,8 @@ import (
 // Allow plugins to register to this slice for inlining
 var InternalPlugins PluginList
 
+var synced bool
+
 // Interface describing a plugin
 type Plugin interface {
 	// Get the name of the plugin (the file name without extensions)
@@ -104,10 +107,17 @@ func (p PluginList) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
 
 // NewManager creates a new manager for looking up plugins on the file system
 func NewManager(pluginDir string, lookupInPath bool) *Manager {
-	return &Manager{
+	m := &Manager{
 		pluginsDir:   pluginDir,
 		lookupInPath: lookupInPath,
 	}
+	if !synced {
+		for _, p := range pkgplugin.InternalPlugins {
+			m.AppendPlugin(p)
+		}
+		synced = true
+	}
+	return m
 }
 
 func (manager *Manager) AppendPlugin(plugin Plugin) {