Add kustomize build flag --enable_managedby_label

kustomize/go.mod

@@ -23,3 +23,5 @@ exclude (
 	github.com/russross/blackfriday v2.0.0+incompatible
 	sigs.k8s.io/kustomize/api v0.2.0
 )
+
+replace sigs.k8s.io/kustomize/api => ../api

kustomize/internal/commands/build/build.go

@@ -77,6 +77,7 @@ func NewCmdBuild(out io.Writer) *cobra.Command {
 	addFlagLoadRestrictor(cmd.Flags())
 	addFlagEnablePlugins(cmd.Flags())
 	addFlagReorderOutput(cmd.Flags())
+	addFlagEnableManagedbyLabel(cmd.Flags())
 	return cmd
 }
 
@@ -114,6 +115,9 @@ func (o *Options) makeOptions() *krusty.Options {
 	} else {
 		opts.PluginConfig = konfig.DisabledPluginConfig()
 	}
+	if isManagedbyLabelEnabled() {
+		opts.AddManagedbyLabel = true
+	}
 	return opts
 }
 

kustomize/internal/commands/build/flagaddmanagedby.go

@@ -0,0 +1,38 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package build
+
+import (
+	"os"
+
+	"github.com/spf13/pflag"
+
+	"sigs.k8s.io/kustomize/api/konfig"
+)
+
+const (
+	flagEnableManagedbyLabelName = "enable_managedby_label"
+	flagEnableManagedbyLabelHelp = `enable adding ` + konfig.ManagedbyLabelKey
+)
+
+var (
+	flagEnableManagedbyLabelValue = false
+)
+
+func addFlagEnableManagedbyLabel(set *pflag.FlagSet) {
+	set.BoolVar(
+		&flagEnableManagedbyLabelValue, flagEnableManagedbyLabelName,
+		false, flagEnableManagedbyLabelHelp)
+}
+
+func isManagedbyLabelEnabled() bool {
+	if flagEnableManagedbyLabelValue {
+		return true
+	}
+	enableLabel, isSet := os.LookupEnv(konfig.EnableManagedbyLabelEnv)
+	if isSet && enableLabel == "on" {
+		return true
+	}
+	return false
+}