add comments in refvar transformer

Refactor change

pkg/app/application.go

@@ -79,7 +79,7 @@ func (a *applicationImpl) Resources() (resmap.ResMap, error) {
 	if err != nil {
 		return nil, err
 	}
-	t, err := a.getHashAndReferenceTransformer(res)
+	t, err := a.newHashAndReferenceTransformer(res)
 	if err != nil {
 		return nil, err
 	}
@@ -125,7 +125,7 @@ func (a *applicationImpl) SemiResources() (resmap.ResMap, error) {
 		return nil, errs
 	}
 
-	t, err := a.getTransformer(patches)
+	t, err := a.newTransformer(patches)
 	if err != nil {
 		return nil, err
 	}
@@ -144,7 +144,7 @@ func (a *applicationImpl) RawResources() (resmap.ResMap, error) {
 	if err != nil {
 		return nil, err
 	}
-	t, err := a.getHashAndReferenceTransformer(res)
+	t, err := a.newHashAndReferenceTransformer(res)
 	if err != nil {
 		return nil, err
 	}
@@ -220,12 +220,12 @@ func (a *applicationImpl) subApp() ([]Application, error) {
 	return apps, nil
 }
 
-// getTransformer generates the following transformers:
+// newTransformer generates the following transformers:
 // 1) apply overlay
 // 2) name prefix
 // 3) apply labels
 // 4) apply annotations
-func (a *applicationImpl) getTransformer(patches []*resource.Resource) (transformers.Transformer, error) {
+func (a *applicationImpl) newTransformer(patches []*resource.Resource) (transformers.Transformer, error) {
 	ts := []transformers.Transformer{}
 
 	ot, err := transformers.NewOverlayTransformer(patches)
@@ -257,11 +257,11 @@ func (a *applicationImpl) getTransformer(patches []*resource.Resource) (transfor
 	return transformers.NewMultiTransformer(ts), nil
 }
 
-// getHashAndReferenceTransformer generates the following transformers:
+// newHashAndReferenceTransformer generates the following transformers:
 // 1) name hash for configmap and secrests
 // 2) apply name reference
 // 3) apply reference variables
-func (a *applicationImpl) getHashAndReferenceTransformer(allRes resmap.ResMap) (transformers.Transformer, error) {
+func (a *applicationImpl) newHashAndReferenceTransformer(allRes resmap.ResMap) (transformers.Transformer, error) {
 	ts := []transformers.Transformer{}
 	nht := transformers.NewNameHashTransformer()
 	ts = append(ts, nht)
@@ -271,7 +271,7 @@ func (a *applicationImpl) getHashAndReferenceTransformer(allRes resmap.ResMap) (
 		return nil, err
 	}
 	ts = append(ts, nrt)
-	t, err := a.getVariableReferenceTransformer(allRes)
+	t, err := a.newVariableReferenceTransformer(allRes)
 	if err != nil {
 		return nil, err
 	}
@@ -280,7 +280,7 @@ func (a *applicationImpl) getHashAndReferenceTransformer(allRes resmap.ResMap) (
 	return transformers.NewMultiTransformer(ts), nil
 }
 
-func (a *applicationImpl) getVariableReferenceTransformer(allRes resmap.ResMap) (transformers.Transformer, error) {
+func (a *applicationImpl) newVariableReferenceTransformer(allRes resmap.ResMap) (transformers.Transformer, error) {
 	refvars, err := a.resolveRefVars(allRes)
 	if err != nil {
 		return nil, err
@@ -314,9 +314,9 @@ func (a *applicationImpl) resolveRefVars(resources resmap.ResMap) (map[string]st
 	}
 
 	for _, refvar := range vars {
-		refGVKN := gvkn(refvar)
+		refGVKN := resource.NewResId(refvar.ObjRef.GroupVersionKind(), refvar.ObjRef.Name)
 		if r, found := resources[refGVKN]; found {
-			s, err := getFieldAsString(r.Unstruct().UnstructuredContent(), strings.Split(refvar.FieldRef.FieldPath, "."))
+			s, err := resource.GetFieldValue(r.Unstruct().UnstructuredContent(), strings.Split(refvar.FieldRef.FieldPath, "."))
 			if err != nil {
 				return nil, fmt.Errorf("failed to resolve referred var: %+v", refvar)
 			}

pkg/app/var.go

@@ -1,54 +0,0 @@
-/*
-Copyright 2018 The Kubernetes Authors.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-package app
-
-import (
-	"fmt"
-
-	"github.com/kubernetes-sigs/kustomize/pkg/resource"
-	"github.com/kubernetes-sigs/kustomize/pkg/types"
-)
-
-func gvkn(rv types.Var) resource.ResId {
-	return resource.NewResId(rv.ObjRef.GroupVersionKind(), rv.ObjRef.Name)
-}
-
-func getFieldAsString(m map[string]interface{}, pathToField []string) (string, error) {
-	if len(pathToField) == 0 {
-		return "", fmt.Errorf("Field not found")
-	}
-
-	if len(pathToField) == 1 {
-		if v, found := m[pathToField[0]]; found {
-			if s, ok := v.(string); ok {
-				return s, nil
-			}
-			return "", fmt.Errorf("value at fieldpath is not of string type")
-		}
-		return "", fmt.Errorf("field at given fieldpath does not exist")
-	}
-
-	curr, rest := pathToField[0], pathToField[1]
-
-	v := m[curr]
-	switch typedV := v.(type) {
-	case map[string]interface{}:
-		return getFieldAsString(typedV, []string{rest})
-	default:
-		return "", fmt.Errorf("%#v is not expected to be a primitive type", typedV)
-	}
-}

pkg/resource/resource.go

@@ -18,6 +18,7 @@ package resource
 
 import (
 	"encoding/json"
+	"fmt"
 
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -108,3 +109,29 @@ func newUnstructuredFromObject(in runtime.Object) (*unstructured.Unstructured, e
 	err = out.UnmarshalJSON(marshaled)
 	return &out, err
 }
+
+func GetFieldValue(m map[string]interface{}, pathToField []string) (string, error) {
+	if len(pathToField) == 0 {
+		return "", fmt.Errorf("Field not found")
+	}
+
+	if len(pathToField) == 1 {
+		if v, found := m[pathToField[0]]; found {
+			if s, ok := v.(string); ok {
+				return s, nil
+			}
+			return "", fmt.Errorf("value at fieldpath is not of string type")
+		}
+		return "", fmt.Errorf("field at given fieldpath does not exist")
+	}
+
+	curr, rest := pathToField[0], pathToField[1]
+
+	v := m[curr]
+	switch typedV := v.(type) {
+	case map[string]interface{}:
+		return GetFieldValue(typedV, []string{rest})
+	default:
+		return "", fmt.Errorf("%#v is not expected to be a primitive type", typedV)
+	}
+}

pkg/resource/resource_test.go

@@ -14,10 +14,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package app
+package resource
 
 import (
-	"strings"
 	"testing"
 )
 
@@ -31,21 +30,37 @@ func TestGetFieldAsString(t *testing.T) {
 			"name": "service-name",
 		},
 	}
-	p := []string{"Kind"}
-	s, _ := getFieldAsString(m, p)
-	if s != "Service" {
-		t.Errorf("Expected to get Service, but actually got %s", s)
+
+	tests := []struct {
+		pathToField   []string
+		expectedName  string
+		expectedError bool
+	}{
+		{
+			pathToField:   []string{"Kind"},
+			expectedName:  "Service",
+			expectedError: false,
+		},
+		{
+			pathToField:   []string{"metadata", "name"},
+			expectedName:  "service-name",
+			expectedError: false,
+		},
+		{
+			pathToField:   []string{"metadata", "non-existing-field"},
+			expectedName:  "",
+			expectedError: true,
+		},
 	}
 
-	p = []string{"metadata", "name"}
-	s, _ = getFieldAsString(m, p)
-	if s != "service-name" {
-		t.Errorf("Expected to get service-name, but actually got %s", s)
-	}
-
-	p = []string{"metadata", "non-existing-field"}
-	s, err := getFieldAsString(m, p)
-	if !strings.HasSuffix(err.Error(), "field at given fieldpath does not exist") {
-		t.Errorf("Unexpected failure due to incorrect error message %s", err.Error())
+	for _, test := range tests {
+		s, err := GetFieldValue(m, test.pathToField)
+		if test.expectedError && err == nil {
+			t.Fatalf("should return error, but no error returned")
+		} else {
+			if test.expectedName != s {
+				t.Fatalf("Got:%s expected:%s", s, test.expectedName)
+			}
+		}
 	}
 }

pkg/transformers/refvars.go

@@ -13,6 +13,7 @@ type refvarTransformer struct {
 	vars        map[string]string
 }
 
+// NewRefVarTransformer returns a Trasformer that replaces $(VAR) style variables with values.
 func NewRefVarTransformer(vars map[string]string) (Transformer, error) {
 	return &refvarTransformer{
 		vars: vars,
@@ -33,17 +34,16 @@ func NewRefVarTransformer(vars map[string]string) (Transformer, error) {
 	}, nil
 }
 
+// Transform determines the final values of variables:
+//
+// 1.  Determine the final value of each variable:
+//     a.  If the variable's Value is set, expand the `$(var)` references to other
+//         variables in the .Value field; the sources of variables are the declared
+//         variables of the container and the service environment variables
+//     b.  If a source is defined for an environment variable, resolve the source
+// 2.  Create the container's environment in the order variables are declared
+// 3.  Add remaining service environment vars
 func (rv *refvarTransformer) Transform(resources resmap.ResMap) error {
-	// Determine the final values of variables:
-	//
-	// 1.  Determine the final value of each variable:
-	//     a.  If the variable's Value is set, expand the `$(var)` references to other
-	//         variables in the .Value field; the sources of variables are the declared
-	//         variables of the container and the service environment variables
-	//     b.  If a source is defined for an environment variable, resolve the source
-	// 2.  Create the container's environment in the order variables are declared
-	// 3.  Add remaining service environment vars
-
 	for GVKn := range resources {
 		obj := resources[GVKn].Unstruct()
 		objMap := obj.UnstructuredContent()

pkg/types/defaulting.go

@@ -1,27 +0,0 @@
-/*
-Copyright 2017 The Kubernetes Authors.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-package types
-
-import (
-	corev1 "k8s.io/api/core/v1"
-)
-
-func (v *Var) Defaulting() {
-	if (corev1.ObjectFieldSelector{}) == v.FieldRef {
-		v.FieldRef = corev1.ObjectFieldSelector{FieldPath: "metadata.name"}
-	}
-}

pkg/types/kustomization.go

@@ -16,10 +16,6 @@ limitations under the License.
 
 package types
 
-import (
-	corev1 "k8s.io/api/core/v1"
-)
-
 // Kustomization holds the information needed to generate customized k8s api resources.
 type Kustomization struct {
 	// NamePrefix will prefix the names of all resources mentioned in the kustomization
@@ -136,23 +132,3 @@ type DataSources struct {
 	// i.e. a Docker .env file or a .ini file.
 	EnvSource string `json:"env,omitempty" yaml:"env,omitempty"`
 }
-
-// Var represents a variable whose value will be sourced
-// from a field in a Kubernetes object.
-type Var struct {
-	// Value of identifier name e.g. FOO used in container args, annotations
-	// Appears in pod template as $(FOO)
-	Name string `json:"name" yaml:"name"`
-
-	// ObjRef must refer to a Kubernetes resource under the
-	// purview of this kustomization. ObjRef should use the
-	// raw name of the object (the name specified in its YAML,
-	// before addition of a namePrefix).
-	ObjRef corev1.ObjectReference `json:"objref" yaml:"objref"`
-
-	// FieldRef refers to the field of the object referred to by
-	// ObjRef whose value will be extracted for use in
-	// replacing $(FOO).
-	// If unspecified, this defaults to fieldpath: metadata.name
-	FieldRef corev1.ObjectFieldSelector `json:"fieldref,omitempty" yaml:"objref,omitempty"`
-}

pkg/types/var.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package types
+
+import (
+	corev1 "k8s.io/api/core/v1"
+)
+
+// Var represents a variable whose value will be sourced
+// from a field in a Kubernetes object.
+type Var struct {
+	// Value of identifier name e.g. FOO used in container args, annotations
+	// Appears in pod template as $(FOO)
+	Name string `json:"name" yaml:"name"`
+
+	// ObjRef must refer to a Kubernetes resource under the
+	// purview of this kustomization. ObjRef should use the
+	// raw name of the object (the name specified in its YAML,
+	// before addition of a namePrefix).
+	ObjRef corev1.ObjectReference `json:"objref" yaml:"objref"`
+
+	// FieldRef refers to the field of the object referred to by
+	// ObjRef whose value will be extracted for use in
+	// replacing $(FOO).
+	// If unspecified, this defaults to fieldpath: metadata.name
+	FieldRef corev1.ObjectFieldSelector `json:"fieldref,omitempty" yaml:"objref,omitempty"`
+}
+
+func (v *Var) Defaulting() {
+	if (corev1.ObjectFieldSelector{}) == v.FieldRef {
+		v.FieldRef = corev1.ObjectFieldSelector{FieldPath: "metadata.name"}
+	}
+}