Implement replica transformer as patch alternative

plugin/builtin/ReplicaCountTransformer.go

@@ -0,0 +1,57 @@
+// Code generated by pluginator on ReplicaCountTransformer; DO NOT EDIT.
+package builtin
+
+import (
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/replica"
+	"sigs.k8s.io/kustomize/pkg/resid"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/transformers/config"
+	"sigs.k8s.io/yaml"
+)
+
+// Find matching replicas declarations and replace
+// the count.
+type ReplicaCountTransformerPlugin struct {
+	Replica    replica.Replica    `json:"replica,omitempty" yaml:"replica,omitempty"`
+	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
+}
+
+func NewReplicaCountTransformerPlugin() *ReplicaCountTransformerPlugin {
+	return &ReplicaCountTransformerPlugin{}
+}
+
+func (p *ReplicaCountTransformerPlugin) Config(
+	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
+
+	p.Replica = replica.Replica{}
+	p.FieldSpecs = nil
+	return yaml.Unmarshal(c, p)
+}
+
+func (p *ReplicaCountTransformerPlugin) Transform(m resmap.ResMap) error {
+	matcher := func(r resid.ResId) bool {
+		return r.ItemId.Name == p.Replica.Name
+	}
+
+	for _, r := range m.GetMatchingIds(matcher) {
+		kMap := m[r].Kunstructured.Map()
+
+		specInterface, ok := kMap["spec"]
+		if !ok {
+			return errors.New("'spec' not specified, replicas cannot be modified")
+		}
+
+		if spec, ok := specInterface.(map[string]interface{}); ok {
+			spec["replicas"] = p.Replica.Count
+			kMap["spec"] = spec
+		} else {
+			return errors.New("'spec' not structured as expected")
+		}
+
+		m[r].Kunstructured.SetMap(kMap)
+	}
+
+	return nil
+}

plugin/builtin/replicacounttransformer/ReplicaCountTransformer.go

@@ -0,0 +1,58 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+//go:generate go run sigs.k8s.io/kustomize/plugin/pluginator
+package main
+
+import (
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/replica"
+	"sigs.k8s.io/kustomize/pkg/resid"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/transformers/config"
+	"sigs.k8s.io/yaml"
+)
+
+// Find matching replicas declarations and replace the count.
+// Eases the kustomization configuration of replica changes.
+type plugin struct {
+	Replica    replica.Replica    `json:"replica,omitempty" yaml:"replica,omitempty"`
+	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
+}
+
+var KustomizePlugin plugin
+
+func (p *plugin) Config(
+	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
+
+	p.Replica = replica.Replica{}
+	p.FieldSpecs = nil
+	return yaml.Unmarshal(c, p)
+}
+
+func (p *plugin) Transform(m resmap.ResMap) error {
+	matcher := func(r resid.ResId) bool {
+		return r.ItemId.Name == p.Replica.Name
+	}
+
+	for _, r := range m.GetMatchingIds(matcher) {
+		kMap := m[r].Kunstructured.Map()
+
+		specInterface, ok := kMap["spec"]
+		if !ok {
+			return errors.New("'spec' not specified, replicas cannot be modified")
+		}
+
+		if spec, ok := specInterface.(map[string]interface{}); ok {
+			spec["replicas"] = p.Replica.Count
+			kMap["spec"] = spec
+		} else {
+			return errors.New("'spec' not structured as expected")
+		}
+
+		m[r].Kunstructured.SetMap(kMap)
+	}
+
+	return nil
+}

plugin/builtin/replicacounttransformer/ReplicaCountTransformer_test.go

@@ -0,0 +1,49 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package main_test
+
+import (
+	"testing"
+
+	"sigs.k8s.io/kustomize/pkg/kusttest"
+	"sigs.k8s.io/kustomize/plugin"
+)
+
+func TestReplicaCountTransformer(t *testing.T) {
+	tc := plugin.NewEnvForTest(t).Set()
+	defer tc.Reset()
+
+	tc.BuildGoPlugin(
+		"builtin", "", "ReplicaCountTransformer")
+
+	th := kusttest_test.NewKustTestPluginHarness(t, "/app")
+
+	rm := th.LoadAndRunTransformer(`
+apiVersion: builtin
+kind: ReplicaCountTransformer
+metadata:
+  name: notImportantHere
+replica:
+  name: deploy1
+  count: 23
+`, `
+group: apps
+apiVersion: v1
+kind: Deployment
+metadata:
+  name: deploy1
+spec:
+  replicas: 1
+`)
+
+	th.AssertActualEqualsExpected(rm, `
+apiVersion: v1
+group: apps
+kind: Deployment
+metadata:
+  name: deploy1
+spec:
+  replicas: 23
+`)
+}