Merge pull request #2327 from mortent/StrategicMergeTransformer

Add strategic merge patch filter based on kyaml libraries

api/builtins/PatchStrategicMergeTransformer.go

@@ -4,11 +4,16 @@
 package builtins
 
 import (
+	"encoding/json"
 	"fmt"
 
+	kyaml "sigs.k8s.io/kustomize/kyaml/yaml"
+
+	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
 	"sigs.k8s.io/kustomize/api/types"
+	"sigs.k8s.io/kustomize/kyaml/filtersutil"
 	"sigs.k8s.io/yaml"
 )
 
@@ -17,6 +22,8 @@ type PatchStrategicMergeTransformerPlugin struct {
 	loadedPatches []*resource.Resource
 	Paths         []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
 	Patches       string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
+
+	YAMLSupport bool `json:"yamlSupport,omitempty" yaml:"yamlSupport,omitempty"`
 }
 
 func (p *PatchStrategicMergeTransformerPlugin) Config(
@@ -69,22 +76,42 @@ func (p *PatchStrategicMergeTransformerPlugin) Transform(m resmap.ResMap) error
 		if err != nil {
 			return err
 		}
-		err = target.Patch(patch.Kunstructured)
-		if err != nil {
-			return err
-		}
-		// remove the resource from resmap
-		// when the patch is to $patch: delete that target
-		if len(target.Map()) == 0 {
-			err = m.Remove(target.CurId())
+		if !p.YAMLSupport {
+			err = target.Patch(patch.Kunstructured)
 			if err != nil {
 				return err
 			}
+			// remove the resource from resmap
+			// when the patch is to $patch: delete that target
+			if len(target.Map()) == 0 {
+				err = m.Remove(target.CurId())
+				if err != nil {
+					return err
+				}
+			}
+		} else {
+			node, err := getRNode(patch)
+			if err != nil {
+				return err
+			}
+			err = filtersutil.ApplyToJSON(patchstrategicmerge.Filter{
+				Patch: node,
+			}, target.Kunstructured)
 		}
 	}
 	return nil
 }
 
+//TODO: Remove this once the next version of kyaml is released which
+// exposes GetRNode from the filutersutil package.
+func getRNode(k json.Marshaler) (*kyaml.RNode, error) {
+	j, err := k.MarshalJSON()
+	if err != nil {
+		return nil, err
+	}
+	return kyaml.Parse(string(j))
+}
+
 func NewPatchStrategicMergeTransformerPlugin() resmap.TransformerPlugin {
 	return &PatchStrategicMergeTransformerPlugin{}
 }

api/filters/patchstrategicmerge/doc.go

@@ -0,0 +1,6 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Package patchstrategicmerge contains a kio.Filter implementation of the
+// kustomize strategic merge patch transformer.
+package patchstrategicmerge

api/filters/patchstrategicmerge/example_test.go

@@ -0,0 +1,49 @@
+// Copyright 2020 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package patchstrategicmerge
+
+import (
+	"bytes"
+	"log"
+	"os"
+
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func ExampleFilter() {
+	err := kio.Pipeline{
+		Inputs: []kio.Reader{&kio.ByteReader{Reader: bytes.NewBufferString(`
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+spec:
+  replicas: 3
+`)}},
+		Filters: []kio.Filter{Filter{
+			Patch: yaml.MustParse(`
+spec:
+  template:
+    containers:
+    - image: nginx
+`),
+		}},
+		Outputs: []kio.Writer{kio.ByteWriter{Writer: os.Stdout}},
+	}.Execute()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Output:
+	// apiVersion: example.com/v1
+	// kind: Foo
+	// metadata:
+	//   name: instance
+	// spec:
+	//   replicas: 3
+	//   template:
+	//     containers:
+	//     - image: nginx
+}

api/filters/patchstrategicmerge/patchstrategicmerge.go

@@ -0,0 +1,21 @@
+package patchstrategicmerge
+
+import (
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+	"sigs.k8s.io/kustomize/kyaml/yaml/merge2"
+)
+
+type Filter struct {
+	Patch *yaml.RNode
+}
+
+var _ kio.Filter = Filter{}
+
+func (pf Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	return kio.FilterAll(yaml.FilterFunc(pf.run)).Filter(nodes)
+}
+
+func (pf Filter) run(node *yaml.RNode) (*yaml.RNode, error) {
+	return merge2.Merge(pf.Patch, node)
+}

api/filters/patchstrategicmerge/patchstrategicmerge_test.go

@@ -0,0 +1,82 @@
+package patchstrategicmerge
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	filtertest "sigs.k8s.io/kustomize/api/testutils/filtertest"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func TestFilter(t *testing.T) {
+	testCases := map[string]struct {
+		input    string
+		patch    *yaml.RNode
+		expected string
+	}{
+		"simple patch": {
+			input: `
+apiVersion: apps/v1
+metadata:
+  name: myDeploy
+kind: Deployment
+`,
+			patch: yaml.MustParse(`
+metadata:
+  name: yourDeploy
+`),
+			expected: `
+apiVersion: apps/v1
+metadata:
+  name: yourDeploy
+kind: Deployment
+`,
+		},
+		"nested patch": {
+			input: `
+apiVersion: apps/v1
+metadata:
+  name: myDeploy
+kind: Deployment
+spec:
+  containers:
+  - name: nginx
+    args:
+    - abc
+`,
+			patch: yaml.MustParse(`
+spec:
+  containers:
+  - name: nginx
+    args:
+    - def
+`),
+			expected: `
+apiVersion: apps/v1
+metadata:
+  name: myDeploy
+kind: Deployment
+spec:
+  containers:
+  - name: nginx
+    args:
+    - def
+`,
+		},
+	}
+
+	for tn, tc := range testCases {
+		t.Run(tn, func(t *testing.T) {
+			f := Filter{
+				Patch: tc.patch,
+			}
+			if !assert.Equal(t,
+				strings.TrimSpace(tc.expected),
+				strings.TrimSpace(
+					filtertest.RunFilter(t, tc.input, f))) {
+				t.FailNow()
+			}
+		})
+	}
+}