Add calvin duplicator example plugin.

plugin/someteam.example.com/v1/calvinduplicator/CalvinDuplicator.go

@@ -0,0 +1,47 @@
+// Copyright 2021 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"fmt"
+	"sigs.k8s.io/kustomize/api/resmap"
+	"sigs.k8s.io/yaml"
+)
+
+const calvinName = "calvin"
+
+// Look for resources named $Name, and duplicate them N times,
+// leaving resources named ${Name}-1, ..., ${Name}-N.
+type plugin struct {
+	// Name of resource to duplicate.
+	Name string `json:"name,omitempty" yaml:"name,omitempty"`
+
+	// Count is how many duplicates to make.
+	Count int `json:"count,omitempty" yaml:"count,omitempty"`
+}
+
+//nolint: golint
+//noinspection GoUnusedGlobalVariable
+var KustomizePlugin plugin
+
+func (p *plugin) Config(_ *resmap.PluginHelpers, c []byte) error {
+	return yaml.Unmarshal(c, p)
+}
+
+func (p *plugin) Transform(m resmap.ResMap) error {
+	list := m.Resources()
+	m.Clear()
+	for _, r := range list {
+		if r.GetName() == p.Name {
+			for i := 1; i <= p.Count; i++ {
+				c := r.DeepCopy()
+				c.SetName(fmt.Sprintf("%s-%d", p.Name, i))
+				m.Append(c)
+			}
+		} else {
+			m.Append(r)
+		}
+	}
+	return nil
+}