Maintain resources in order loaded.

2026-07-17 01:39:06 +00:00 · 2019-06-03 11:22:53 -07:00
parent af57fc3ece
commit 4162dbc2d8
39 changed files with 1074 additions and 617 deletions
--- a/pkg/resmap/factory.go
+++ b/pkg/resmap/factory.go
@@ -1,27 +1,13 @@
-/*
-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.
-*/
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0

 package resmap

 import (
-	"fmt"
-
 	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/internal/kusterr"
 	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/resid"
 	"sigs.k8s.io/kustomize/pkg/resource"
 	"sigs.k8s.io/kustomize/pkg/types"
 )
@@ -41,11 +27,17 @@ func (rmF *Factory) RF() *resource.Factory {
 	return rmF.resF
 }

+func New() ResMap {
+	return newOne()
+}
+
 // FromResource returns a ResMap with one entry.
 func (rmF *Factory) FromResource(res *resource.Resource) ResMap {
-	result := ResMap{}
-	result[res.Id()] = res
-	return result
+	m, err := newResMapFromResourceSlice([]*resource.Resource{res})
+	if err != nil {
+		panic(err)
+	}
+	return m
 }

 // FromFile returns a ResMap given a resource path.
@@ -55,26 +47,41 @@ func (rmF *Factory) FromFile(
 	if err != nil {
 		return nil, err
 	}
-	res, err := rmF.NewResMapFromBytes(content)
+	m, err := rmF.NewResMapFromBytes(content)
 	if err != nil {
 		return nil, kusterr.Handler(err, path)
 	}
-	return res, nil
+	return m, nil
 }

-// newResMapFromBytes decodes a list of objects in byte array format.
+// NewResMapFromBytes decodes a list of objects in byte array format.
 func (rmF *Factory) NewResMapFromBytes(b []byte) (ResMap, error) {
 	resources, err := rmF.resF.SliceFromBytes(b)
 	if err != nil {
 		return nil, err
 	}
-	result := ResMap{}
-	for _, res := range resources {
-		id := res.Id()
-		if _, found := result[id]; found {
-			return result, fmt.Errorf("GroupVersionKindName: %#v already exists in the map", id)
+	return newResMapFromResourceSlice(resources)
+}
+
+// Deprecated.
+// FromMap returns a ResMap with arbitrary internal ordering,
+// panicing on error.  For tests only.
+// See also ErrorIfNotEqual.
+func FromMap(arg map[resid.ResId]*resource.Resource) ResMap {
+	result, err := fromMap(arg)
+	if err != nil {
+		panic(err)
+	}
+	return result
+}
+
+func fromMap(arg map[resid.ResId]*resource.Resource) (ResMap, error) {
+	result := New()
+	for id, r := range arg {
+		err := result.AppendWithId(id, r)
+		if err != nil {
+			return nil, err
 		}
-		result[id] = res
 	}
 	return result, nil
 }
@@ -136,13 +143,12 @@ func (rmF *Factory) FromSecretArgs(
 }

 func newResMapFromResourceSlice(resources []*resource.Resource) (ResMap, error) {
-	result := ResMap{}
+	result := New()
 	for _, res := range resources {
-		id := res.Id()
-		if _, found := result[id]; found {
-			return nil, fmt.Errorf("duplicated %#v is not allowed", id)
+		err := result.Append(res)
+		if err != nil {
+			return nil, err
 		}
-		result[id] = res
 	}
 	return result, nil
 }
--- a/pkg/resmap/factory_test.go
+++ b/pkg/resmap/factory_test.go
@@ -1,18 +1,5 @@
-/*
-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.
-*/
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0

 package resmap_test

@@ -21,6 +8,8 @@ import (
 	"reflect"
 	"testing"

+	"sigs.k8s.io/kustomize/pkg/resource"
+
 	"sigs.k8s.io/kustomize/internal/loadertest"
 	"sigs.k8s.io/kustomize/pkg/fs"
 	"sigs.k8s.io/kustomize/pkg/gvk"
@@ -57,14 +46,15 @@ metadata:
 	if ferr := l.AddFile("/whatever/project/deployment.yaml", []byte(resourceStr)); ferr != nil {
 		t.Fatalf("Error adding fake file: %v\n", ferr)
 	}
-	expected := ResMap{resid.NewResId(deploy, "dply1"): rf.FromMap(
-		map[string]interface{}{
-			"apiVersion": "apps/v1",
-			"kind":       "Deployment",
-			"metadata": map[string]interface{}{
-				"name": "dply1",
-			},
-		}),
+	expected := FromMap(map[resid.ResId]*resource.Resource{
+		resid.NewResId(deploy, "dply1"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "apps/v1",
+				"kind":       "Deployment",
+				"metadata": map[string]interface{}{
+					"name": "dply1",
+				},
+			}),
 		resid.NewResId(deploy, "dply2"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -82,11 +72,10 @@ metadata:
 					"namespace": "test",
 				},
 			}),
-	}
-
+	})
 	m, _ := rmF.FromFile(l, "deployment.yaml")
-	if len(m) != 3 {
-		t.Fatalf("%#v should contain 3 appResource, but got %d", m, len(m))
+	if m.Size() != 3 {
+		t.Fatalf("result should contain 3, but got %d", m.Size())
 	}
 	if err := expected.ErrorIfNotEqual(m); err != nil {
 		t.Fatalf("actual doesn't match expected: %v", err)
@@ -104,24 +93,23 @@ kind: ConfigMap
 metadata:
  name: cm2
 `)
-	expected := ResMap{
-		resid.NewResId(cmap, "cm1"): rf.FromMap(
-			map[string]interface{}{
-				"apiVersion": "v1",
-				"kind":       "ConfigMap",
-				"metadata": map[string]interface{}{
-					"name": "cm1",
-				},
-			}),
-		resid.NewResId(cmap, "cm2"): rf.FromMap(
-			map[string]interface{}{
-				"apiVersion": "v1",
-				"kind":       "ConfigMap",
-				"metadata": map[string]interface{}{
-					"name": "cm2",
-				},
-			}),
-	}
+	expected := New()
+	expected.Append(rf.FromMap(
+		map[string]interface{}{
+			"apiVersion": "v1",
+			"kind":       "ConfigMap",
+			"metadata": map[string]interface{}{
+				"name": "cm1",
+			},
+		}))
+	expected.Append(rf.FromMap(
+		map[string]interface{}{
+			"apiVersion": "v1",
+			"kind":       "ConfigMap",
+			"metadata": map[string]interface{}{
+				"name": "cm2",
+			},
+		}))
 	m, err := rmF.NewResMapFromBytes(encoded)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -158,7 +146,7 @@ func TestNewFromConfigMaps(t *testing.T) {
 			},
 			filepath: "/whatever/project/app.env",
 			content:  "DB_USERNAME=admin\nDB_PASSWORD=somepw",
-			expected: ResMap{
+			expected: FromMap(map[resid.ResId]*resource.Resource{
 				resid.NewResId(cmap, "envConfigMap"): rf.FromMapAndOption(
 					map[string]interface{}{
 						"apiVersion": "v1",
@@ -171,7 +159,7 @@ func TestNewFromConfigMaps(t *testing.T) {
 							"DB_PASSWORD": "somepw",
 						},
 					}, &types.GeneratorArgs{}, nil),
-			},
+			}),
 		},

 		{
@@ -187,7 +175,7 @@ func TestNewFromConfigMaps(t *testing.T) {
 			},
 			filepath: "/whatever/project/app-init.ini",
 			content:  "FOO=bar\nBAR=baz\n",
-			expected: ResMap{
+			expected: FromMap(map[resid.ResId]*resource.Resource{
 				resid.NewResId(cmap, "fileConfigMap"): rf.FromMapAndOption(
 					map[string]interface{}{
 						"apiVersion": "v1",
@@ -201,7 +189,7 @@ BAR=baz
 `,
 						},
 					}, &types.GeneratorArgs{}, nil),
-			},
+			}),
 		},
 		{
 			description: "construct config map from literal",
@@ -215,7 +203,7 @@ BAR=baz
 					},
 				},
 			},
-			expected: ResMap{
+			expected: FromMap(map[resid.ResId]*resource.Resource{
 				resid.NewResId(cmap, "literalConfigMap"): rf.FromMapAndOption(
 					map[string]interface{}{
 						"apiVersion": "v1",
@@ -230,7 +218,7 @@ BAR=baz
 							"d": "false",
 						},
 					}, &types.GeneratorArgs{}, nil),
-			},
+			}),
 		},

 		// TODO: add testcase for data coming from multiple sources like
@@ -275,7 +263,7 @@ func TestNewResMapFromSecretArgs(t *testing.T) {
 		t.Fatalf("unexpected error: %v", err)
 	}

-	expected := ResMap{
+	expected := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(secret, "apple"): rf.FromMapAndOption(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -289,7 +277,7 @@ func TestNewResMapFromSecretArgs(t *testing.T) {
 					"DB_PASSWORD": base64.StdEncoding.EncodeToString([]byte("somepw")),
 				},
 			}, &types.GeneratorArgs{}, nil),
-	}
+	})
 	if !reflect.DeepEqual(actual, expected) {
 		t.Fatalf("%#v\ndoesn't match expected:\n%#v", actual, expected)
 	}
--- a/pkg/resmap/resmap.go
+++ b/pkg/resmap/resmap.go
@@ -1,44 +1,348 @@
-/*
-Copyright 2018 The Kubernetes Authors.
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0

-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 resmap implements a map from ResId to Resource that tracks all resources in a kustomization.
+// Package resmap implements a map from ResId to Resource that
+// tracks all resources in a kustomization.
 package resmap

 import (
 	"bytes"
 	"fmt"
-	"reflect"
 	"sort"

+	"github.com/pkg/errors"
+
 	"sigs.k8s.io/kustomize/pkg/resid"
 	"sigs.k8s.io/kustomize/pkg/resource"
 	"sigs.k8s.io/kustomize/pkg/types"
 	"sigs.k8s.io/yaml"
 )

-// ResMap is a map from ResId to Resource.
-type ResMap map[resid.ResId]*resource.Resource
+// ResMap is an interface describing operations on the
+// core kustomize data structure.
+//
+// TODO: delete the commentary below when/if the issues
+// discussed are addressed.
+//
+// It's a temporary(?) interface used during a refactoring
+// from a bare map (map[resid.ResId]*resource.Resource) to a
+// pointer to struct (currently named *resWrangler).
+// Replacing it with a ptr to struct will ease click-thrus
+// to implementation during development.
+// OTOH, hackery in a PR might be easier to see if the
+// interface is left in place.
+//
+// The old (bare map) ResMap had pervasive problems:
+//
+//  * It was mutated inside loops over itself.
+//
+//    Bugs introduced this way were hard to find since the
+//    bare map was recursively passed everywhere, sometimes
+//    mid loop.
+//
+//  * Its keys (ResId) aren't opaque, and are effectively
+//    mutated (via copy and replace) for data storage reasons
+//    as a hack.
+//
+//    ResId was modified a long time ago as a hack to
+//    store name transformation data (prefix and suffix),
+//    destabilizing the basic map concept and resulting
+//    in the need for silly ResId functions like
+//    NewResIdWithPrefixSuffixNamespace, NsGvknEquals,
+//    HasSameLeftmostPrefix, CopyWithNewPrefixSuffix, etc.
+//    plus logic to use them, and overly complex tests.
+//
+//    If this data were stored in the Resource object
+//    (not in Kunstructured, but as a sibling to it next to
+//    GenArgs, references, etc.) then much code could be
+//    deleted and the remainder simplified.
+//
+//  * It doesn't preserve (by definition) value order.
+//
+//    Preserving order is now needed to support
+//    transformer plugins (they aren't commutative).
+//
+// One way to fix this is deprecate use of ResId as the
+// key in favor of ItemId.  See use of the resmap.Remove
+// function to spot the places that need fixing to allow
+// this.
+type ResMap interface {
+	// Size reports the number of resources.
+	Size() int
+
+	// Resources provides a discardable slice
+	// of resource pointers, returned in the order
+	// as appended.
+	Resources() []*resource.Resource
+
+	// Append adds a Resource, automatically computing its
+	// associated Id.
+	// Error on Id collision.
+	Append(*resource.Resource) error
+
+	// AppendWithId adds a Resource with the given Id.
+	// Error on Id collision.
+	AppendWithId(resid.ResId, *resource.Resource) error
+
+	// AsMap returns ResId, *Resource pairs in
+	// arbitrary order via a map.
+	// The map is discardable, and edits to map structure
+	// have no impact on the ResMap.
+	// The Ids are copies, but the resources are pointers,
+	// so the resources themselves can be modified.
+	AsMap() map[resid.ResId]*resource.Resource
+
+	// EncodeAsYaml emits the resources as YAML in a byte slice.
+	// Resources are separated by `---`.
+	EncodeAsYaml() ([]byte, error)
+
+	// Gets the resource with the given Id, else nil.
+	GetById(resid.ResId) *resource.Resource
+
+	// ReplaceResource associates a new resource with
+	// an _existing_ Id.
+	// Error if Id unknown, or if some other Id points
+	// to the same resource object.
+	ReplaceResource(resid.ResId, *resource.Resource) error
+
+	// AllIds returns all known Ids.
+	// Result order is arbitrary.
+	AllIds() []resid.ResId
+
+	// GetMatchingIds returns a slice of Ids that
+	// satisfy the given matcher function.
+	// Result order is arbitrary.
+	GetMatchingIds(IdMatcher) []resid.ResId
+
+	// Remove removes the Id and the resource it points to.
+	Remove(resid.ResId) error
+
+	// ResourcesThatCouldReference returns a new ResMap with
+	// resources that _might_ reference the resource represented
+	// by the argument Id, excluding resources that should
+	// _never_ reference the Id.  E.g., if the Id
+	// refers to a ConfigMap, the returned set may include a
+	// Deployment from the same namespace and exclude Deployments
+	// from other namespaces.  Cluster wide objects are
+	// never excluded.
+	ResourcesThatCouldReference(resid.ResId) ResMap
+
+	// DeepCopy copies the ResMap and underlying resources.
+	DeepCopy() ResMap
+
+	// ShallowCopy copies the ResMap but
+	// not the underlying resources.
+	ShallowCopy() ResMap
+
+	// ErrorIfNotEqual returns an error if the
+	// argument doesn't have the same Ids and resource
+	// data as self. Ordering is _not_ taken into account,
+	// as this function was solely used in tests written
+	// before internal resource order was maintained,
+	// and those tests are initialized with maps which
+	// by definition have random ordering, and will
+	// fail spuriously.
+	// TODO: rename to ErrorIfNotEqualSets
+	// TODO: modify tests to not use resmap.FromMap,
+	// TODO: - and replace this with a stricter equals.
+	ErrorIfNotEqual(ResMap) error
+
+	// Debug prints the ResMap.
+	Debug(title string)
+}
+
+// resWrangler holds the content manipulated by kustomize.
+type resWrangler struct {
+	// Resource list maintained in load (append) order.
+	// This is important for transformers, which must
+	// be performed in a specific order, and for users
+	// who for whatever reasons wish the order they
+	// specify in kustomizations to be maintained and
+	// available as an option for final YAML rendering.
+	rList []*resource.Resource
+
+	// A map from id to an index into rList.
+	// At the time of writing, the ids used as keys in
+	// this map cannot be assumed to match the id
+	// generated from the resource.Id() method pointed
+	// to by the map's value (via rList).  These keys
+	// have been hacked to store prefix/suffix data.
+	rIndex map[resid.ResId]int
+}
+
+func newOne() *resWrangler {
+	result := &resWrangler{}
+	result.rIndex = make(map[resid.ResId]int)
+	return result
+}
+
+// Size implements ResMap.
+func (m *resWrangler) Size() int {
+	if len(m.rList) != len(m.rIndex) {
+		panic(errors.New("class invariant violation"))
+	}
+	return len(m.rList)
+}
+
+func (m *resWrangler) indexOfResource(other *resource.Resource) int {
+	for i, r := range m.rList {
+		if r == other {
+			return i
+		}
+	}
+	return -1
+}
+
+// Resources implements ResMap.
+func (m *resWrangler) Resources() []*resource.Resource {
+	tmp := make([]*resource.Resource, len(m.rList))
+	copy(tmp, m.rList)
+	return tmp
+}
+
+// GetById implements ResMap.
+func (m *resWrangler) GetById(id resid.ResId) *resource.Resource {
+	if i, ok := m.rIndex[id]; ok {
+		return m.rList[i]
+	}
+	return nil
+}
+
+// Append implements ResMap.
+func (m *resWrangler) Append(res *resource.Resource) error {
+	return m.AppendWithId(res.Id(), res)
+}
+
+// Remove implements ResMap.
+func (m *resWrangler) Remove(adios resid.ResId) error {
+	tmp := newOne()
+	for i, r := range m.rList {
+		id, err := m.idMappingToIndex(i)
+		if err != nil {
+			return errors.Wrap(err, "assumption failure in remove")
+		}
+		if id != adios {
+			tmp.AppendWithId(id, r)
+		}
+	}
+	if tmp.Size() != m.Size()-1 {
+		return fmt.Errorf("id %s not found in removal", adios)
+	}
+	m.rIndex = tmp.rIndex
+	m.rList = tmp.rList
+	return nil
+}
+
+// AppendWithId implements ResMap.
+func (m *resWrangler) AppendWithId(id resid.ResId, res *resource.Resource) error {
+	if already, ok := m.rIndex[id]; ok {
+		return fmt.Errorf(
+			"attempt to add res %s at id %s; that id already maps to %d",
+			res, id, already)
+	}
+	i := m.indexOfResource(res)
+	if i >= 0 {
+		return fmt.Errorf(
+			"attempt to add res %s that is already held",
+			res)
+	}
+	m.rList = append(m.rList, res)
+	m.rIndex[id] = len(m.rList) - 1
+	return nil
+}
+
+// ReplaceResource implements ResMap.
+func (m *resWrangler) ReplaceResource(
+	id resid.ResId, newGuy *resource.Resource) error {
+	insertAt, ok := m.rIndex[id]
+	if !ok {
+		return fmt.Errorf(
+			"attempt to reset resource at id %s; that id not used", id)
+	}
+	existingSpot := m.indexOfResource(newGuy)
+	if insertAt == existingSpot {
+		// Be idempotent.
+		return nil
+	}
+	if existingSpot >= 0 {
+		return fmt.Errorf(
+			"the new resource %s is already present", newGuy.Id())
+	}
+	m.rList[insertAt] = newGuy
+	return nil
+}
+
+// AsMap implements ResMap.
+func (m *resWrangler) AsMap() map[resid.ResId]*resource.Resource {
+	result := make(map[resid.ResId]*resource.Resource, m.Size())
+	for id, i := range m.rIndex {
+		result[id] = m.rList[i]
+	}
+	return result
+}
+
+// AllIds implements ResMap.
+func (m *resWrangler) AllIds() (ids []resid.ResId) {
+	ids = make([]resid.ResId, m.Size())
+	i := 0
+	for id := range m.rIndex {
+		ids[i] = id
+		i++
+	}
+	return
+}
+
+// Debug implements ResMap.
+func (m *resWrangler) Debug(title string) {
+	fmt.Println("--------------------------- " + title)
+	firstObj := true
+	for i, r := range m.rList {
+		if firstObj {
+			firstObj = false
+		} else {
+			fmt.Println("---")
+		}
+		fmt.Printf("# %d  %s\n", i, m.debugIdMappingToIndex(i))
+		blob, err := yaml.Marshal(r.Map())
+		if err != nil {
+			panic(err)
+		}
+		fmt.Println(string(blob))
+	}
+}
+
+func (m *resWrangler) debugIdMappingToIndex(i int) string {
+	id, err := m.idMappingToIndex(i)
+	if err != nil {
+		return err.Error()
+	}
+	return id.String()
+}
+
+func (m *resWrangler) idMappingToIndex(i int) (resid.ResId, error) {
+	var foundId resid.ResId
+	found := false
+	for id, index := range m.rIndex {
+		if index == i {
+			if found {
+				return foundId, fmt.Errorf("found multiple")
+			}
+			found = true
+			foundId = id
+		}
+	}
+	if !found {
+		return foundId, fmt.Errorf("cannot find index %d", i)
+	}
+	return foundId, nil
+}

 type IdMatcher func(resid.ResId) bool

-// GetMatchingIds returns a slice of ResId keys from the map
-// that all satisfy the given matcher function.
-func (m ResMap) GetMatchingIds(matches IdMatcher) []resid.ResId {
+// GetMatchingIds implements ResMap.
+func (m *resWrangler) GetMatchingIds(matches IdMatcher) []resid.ResId {
 	var result []resid.ResId
-	for id := range m {
+	for id := range m.rIndex {
 		if matches(id) {
 			result = append(result, id)
 		}
@@ -46,19 +350,19 @@ func (m ResMap) GetMatchingIds(matches IdMatcher) []resid.ResId {
 	return result
 }

-// EncodeAsYaml encodes a ResMap to YAML; encoded objects separated by `---`.
-func (m ResMap) EncodeAsYaml() ([]byte, error) {
-	var ids []resid.ResId
-	for id := range m {
-		ids = append(ids, id)
-	}
+// EncodeAsYaml implements ResMap.
+func (m *resWrangler) EncodeAsYaml() ([]byte, error) {
+	// TODO: should be able to suppress this sort
+	//  and rely on ordering as specified in the ResMap
+	//  internal rList.
+	ids := m.AllIds()
 	sort.Sort(IdSlice(ids))

 	firstObj := true
 	var b []byte
 	buf := bytes.NewBuffer(b)
 	for _, id := range ids {
-		obj := m[id]
+		obj := m.GetById(id)
 		out, err := yaml.Marshal(obj.Map())
 		if err != nil {
 			return nil, err
@@ -79,54 +383,80 @@ func (m ResMap) EncodeAsYaml() ([]byte, error) {
 	return buf.Bytes(), nil
 }

-// ErrorIfNotEqual returns error if maps are not equal.
-func (m ResMap) ErrorIfNotEqual(m2 ResMap) error {
-	if len(m) != len(m2) {
-		var keySet1 []resid.ResId
-		var keySet2 []resid.ResId
-		for id := range m {
-			keySet1 = append(keySet1, id)
-		}
-		for id := range m2 {
-			keySet2 = append(keySet2, id)
-		}
-		return fmt.Errorf("maps has different number of entries: %#v doesn't equals %#v", keySet1, keySet2)
+// ErrorIfNotEqual implements ResMap.
+func (m *resWrangler) ErrorIfNotEqual(other ResMap) error {
+	m2, ok := other.(*resWrangler)
+	if !ok {
+		panic(fmt.Errorf("bad cast to resmapImpl"))
 	}
-	for id, obj1 := range m {
-		obj2, found := m2[id]
-		if !found {
-			return fmt.Errorf("%#v doesn't exist in %#v", id, m2)
+	if m.Size() != m2.Size() {
+		return fmt.Errorf(
+			"lists have different number of entries: %#v doesn't equal %#v",
+			m.rList, m2.rList)
+	}
+	for id, i := range m.rIndex {
+		r1 := m.rList[i]
+		r2 := m2.GetById(id)
+		if r2 == nil {
+			return fmt.Errorf("id in self missing from other; id: %s", id)
 		}
-		if !reflect.DeepEqual(obj1, obj2) {
-			return fmt.Errorf("%#v doesn't deep equal %#v", obj1, obj2)
+		if !r1.KunstructEqual(r2) {
+			return fmt.Errorf(
+				"kuns equal mismatch: \n -- %s,\n -- %s\n\n--\n%#v\n------\n%#v\n",
+				r1, r2, r1, r2)
 		}
 	}
 	return nil
 }

-// DeepCopy clone the resmap into a new one
-func (m ResMap) DeepCopy(rf *resource.Factory) ResMap {
-	mcopy := make(ResMap)
-	for id, obj := range m {
-		mcopy[id] = obj.DeepCopy()
-	}
-	return mcopy
+type resCopier func(r *resource.Resource) *resource.Resource
+
+// ShallowCopy implements ResMap.
+func (m *resWrangler) ShallowCopy() ResMap {
+	return m.makeCopy(
+		func(r *resource.Resource) *resource.Resource {
+			return r
+		})
 }

-// FilterBy returns a subset ResMap containing ResIds with
-// the same namespace and leftmost name prefix and rightmost name
-// as the inputId. If inputId is a cluster level resource, this
-// returns the original ResMap.
-func (m ResMap) FilterBy(inputId resid.ResId) ResMap {
+// DeepCopy implements ResMap.
+func (m *resWrangler) DeepCopy() ResMap {
+	return m.makeCopy(
+		func(r *resource.Resource) *resource.Resource {
+			return r.DeepCopy()
+		})
+}
+
+// makeCopy copies the ResMap.
+func (m *resWrangler) makeCopy(copier resCopier) ResMap {
+	result := &resWrangler{}
+	result.rIndex = make(map[resid.ResId]int, m.Size())
+	result.rList = make([]*resource.Resource, m.Size())
+	for i, r := range m.rList {
+		result.rList[i] = copier(r)
+		id, err := m.idMappingToIndex(i)
+		if err != nil {
+			panic(fmt.Errorf("corrupt index map"))
+		}
+		result.rIndex[id] = i
+	}
+	return result
+}
+
+// ResourcesThatCouldReference implements ResMap.
+func (m *resWrangler) ResourcesThatCouldReference(inputId resid.ResId) ResMap {
 	if inputId.Gvk().IsClusterKind() {
 		return m
 	}
-	result := ResMap{}
-	for id, res := range m {
+	result := New()
+	for id, i := range m.rIndex {
 		if id.Gvk().IsClusterKind() || id.Namespace() == inputId.Namespace() &&
 			id.HasSameLeftmostPrefix(inputId) &&
 			id.HasSameRightmostSuffix(inputId) {
-			result[id] = res
+			err := result.AppendWithId(id, m.rList[i])
+			if err != nil {
+				panic(err)
+			}
 		}
 	}
 	return result
@@ -136,16 +466,16 @@ func (m ResMap) FilterBy(inputId resid.ResId) ResMap {
 // key collision and skipping nil maps.
 // If all of the maps are nil, an empty ResMap is returned.
 func MergeWithErrorOnIdCollision(maps ...ResMap) (ResMap, error) {
-	result := ResMap{}
+	result := New()
 	for _, m := range maps {
 		if m == nil {
 			continue
 		}
-		for id, res := range m {
-			if _, found := result[id]; found {
-				return nil, fmt.Errorf("id '%q' already used", id)
+		for id, res := range m.AsMap() {
+			err := result.AppendWithId(id, res)
+			if err != nil {
+				return nil, err
 			}
-			result[id] = res
 		}
 	}
 	return result, nil
@@ -161,26 +491,40 @@ func MergeWithErrorOnIdCollision(maps ...ResMap) (ResMap, error) {
 // resource X is found to be already in the combined map, then the behavior
 // field for X must be BehaviorMerge or BehaviorReplace.  If X is not in the
 // map, then it's behavior cannot be merge or replace.
+// nolint: gocyclo
 func MergeWithOverride(maps ...ResMap) (ResMap, error) {
+	if len(maps) == 0 {
+		return New(), nil
+	}
 	result := maps[0]
 	if result == nil {
-		result = ResMap{}
+		result = New()
 	}
 	for _, m := range maps[1:] {
 		if m == nil {
 			continue
 		}
-		for id, r := range m {
+		for id, r := range m.AsMap() {
 			matchedId := result.GetMatchingIds(id.GvknEquals)
 			if len(matchedId) == 1 {
 				id = matchedId[0]
+				old := result.GetById(id)
+				if old == nil {
+					return nil, fmt.Errorf("id lookup failure")
+				}
 				switch r.Behavior() {
 				case types.BehaviorReplace:
-					r.Replace(result[id])
-					result[id] = r
+					r.Replace(old)
+					err := result.ReplaceResource(id, r)
+					if err != nil {
+						return nil, err
+					}
 				case types.BehaviorMerge:
-					r.Merge(result[id])
-					result[id] = r
+					r.Merge(old)
+					err := result.ReplaceResource(id, r)
+					if err != nil {
+						return nil, err
+					}
 				default:
 					return nil, fmt.Errorf("id %#v exists; must merge or replace", id)
 				}
@@ -189,7 +533,10 @@ func MergeWithOverride(maps ...ResMap) (ResMap, error) {
 				case types.BehaviorMerge, types.BehaviorReplace:
 					return nil, fmt.Errorf("id %#v does not exist; cannot merge or replace", id)
 				default:
-					result[id] = r
+					err := result.AppendWithId(id, r)
+					if err != nil {
+						return nil, err
+					}
 				}
 			} else {
 				return nil, fmt.Errorf("merge conflict, found multiple objects %v the Resmap %v can merge into", matchedId, id)
--- a/pkg/resmap/resmap_test.go
+++ b/pkg/resmap/resmap_test.go
@@ -1,22 +1,10 @@
-/*
-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.
-*/
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0

 package resmap_test

 import (
+	"fmt"
 	"reflect"
 	"testing"

@@ -34,6 +22,134 @@ var rf = resource.NewFactory(
 	kunstruct.NewKunstructuredFactoryImpl())
 var rmF = NewFactory(rf)

+func doAppend(t *testing.T, w ResMap, r *resource.Resource) {
+	err := w.Append(r)
+	if err != nil {
+		t.Fatalf("append error: %v", err)
+	}
+}
+func doRemove(t *testing.T, w ResMap, id resid.ResId) {
+	err := w.Remove(id)
+	if err != nil {
+		t.Fatalf("remove error: %v", err)
+	}
+}
+
+// Make a resource with a predictable name.
+func makeCm(i int) *resource.Resource {
+	return rf.FromMap(
+		map[string]interface{}{
+			"apiVersion": "v1",
+			"kind":       "ConfigMap",
+			"metadata": map[string]interface{}{
+				"name": fmt.Sprintf("cm%03d", i),
+			},
+		})
+}
+
+func TestAppendRemove(t *testing.T) {
+	w1 := New()
+	doAppend(t, w1, makeCm(1))
+	doAppend(t, w1, makeCm(2))
+	doAppend(t, w1, makeCm(3))
+	doAppend(t, w1, makeCm(4))
+	doAppend(t, w1, makeCm(5))
+	doAppend(t, w1, makeCm(6))
+	doAppend(t, w1, makeCm(7))
+	doRemove(t, w1, makeCm(1).Id())
+	doRemove(t, w1, makeCm(3).Id())
+	doRemove(t, w1, makeCm(5).Id())
+	doRemove(t, w1, makeCm(7).Id())
+
+	w2 := New()
+	doAppend(t, w2, makeCm(2))
+	doAppend(t, w2, makeCm(4))
+	doAppend(t, w2, makeCm(6))
+	if !reflect.DeepEqual(w1, w1) {
+		w1.Debug("w1")
+		w2.Debug("w2")
+		t.Fatalf("mismatch")
+	}
+
+	err := w2.Append(makeCm(6))
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+}
+
+func TestRemove(t *testing.T) {
+	w := New()
+	r := makeCm(1)
+	err := w.Remove(r.Id())
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	err = w.Append(r)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	err = w.Remove(r.Id())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	err = w.Remove(r.Id())
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+}
+
+func TestReplaceResource(t *testing.T) {
+	cm5 := makeCm(5)
+	cm700 := makeCm(700)
+	cm888 := makeCm(888)
+
+	w := New()
+	doAppend(t, w, makeCm(1))
+	doAppend(t, w, makeCm(2))
+	doAppend(t, w, makeCm(3))
+	doAppend(t, w, makeCm(4))
+	doAppend(t, w, cm5)
+	doAppend(t, w, makeCm(6))
+	doAppend(t, w, makeCm(7))
+
+	oldSize := w.Size()
+	err := w.ReplaceResource(cm5.Id(), cm700)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if w.Size() != oldSize {
+		t.Fatalf("unexpected size %d", w.Size())
+	}
+	if w.GetById(cm5.Id()) != cm700 {
+		t.Fatalf("unexpected result")
+	}
+	if err := w.Append(cm5); err == nil {
+		t.Fatalf("expected id already there error")
+	}
+	if err := w.AppendWithId(cm888.Id(), cm5); err != nil {
+		// Okay to add with some unused Id.
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if err := w.Append(cm700); err == nil {
+		t.Fatalf("expected resource already there error")
+	}
+	if err := w.Remove(cm5.Id()); err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if err := w.Append(cm700); err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if err := w.Append(cm5); err == nil {
+		t.Fatalf("expected err; object is still there under id 888")
+	}
+	if err := w.Remove(cm888.Id()); err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if err := w.Append(cm5); err != nil {
+		t.Fatalf("unexpected err; %v", err)
+	}
+}
+
 func TestEncodeAsYaml(t *testing.T) {
 	encoded := []byte(`apiVersion: v1
 kind: ConfigMap
@@ -45,7 +161,7 @@ kind: ConfigMap
 metadata:
  name: cm2
 `)
-	input := ResMap{
+	input := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -62,7 +178,7 @@ metadata:
 					"name": "cm2",
 				},
 			}),
-	}
+	})
 	out, err := input.EncodeAsYaml()
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -73,7 +189,7 @@ metadata:
 }

 func TestDemandOneGvknMatchForId(t *testing.T) {
-	rm1 := ResMap{
+	rm1 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResIdWithPrefixNamespace(cmap, "cm1", "prefix1", "ns1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -90,7 +206,7 @@ func TestDemandOneGvknMatchForId(t *testing.T) {
 					"name": "cm2",
 				},
 			}),
-	}
+	})

 	result := rm1.GetMatchingIds(
 		resid.NewResIdWithPrefixNamespace(cmap, "cm2", "prefix1", "ns1").GvknEquals)
@@ -129,135 +245,147 @@ func TestFilterBy(t *testing.T) {
 		expected ResMap
 	}{
 		"different namespace": {
-			resMap: ResMap{resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix", "namespace1"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix", "namespace1"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 			filter:   resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix", "namespace2"),
-			expected: ResMap{},
+			expected: New(),
 		},
 		"different prefix": {
-			resMap: ResMap{resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix1", "suffix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix1", "suffix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 			filter:   resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix2", "suffix", "namespace"),
-			expected: ResMap{},
+			expected: New(),
 		},
 		"different suffix": {
-			resMap: ResMap{resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix1", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix1", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 			filter:   resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map", "prefix", "suffix2", "namespace"),
-			expected: ResMap{},
+			expected: New(),
 		},
 		"same namespace, same prefix": {
-			resMap: ResMap{resid.NewResIdWithPrefixNamespace(cmap, "config-map1", "prefix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map1",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixNamespace(cmap, "config-map1", "prefix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map1",
+						},
+					}),
+			}),
 			filter: resid.NewResIdWithPrefixNamespace(cmap, "config-map2", "prefix", "namespace"),
-			expected: ResMap{resid.NewResIdWithPrefixNamespace(cmap, "config-map1", "prefix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map1",
-					},
-				}),
-			},
+			expected: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixNamespace(cmap, "config-map1", "prefix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map1",
+						},
+					}),
+			}),
 		},
 		"same namespace, same suffix": {
-			resMap: ResMap{resid.NewResIdWithSuffixNamespace(cmap, "config-map1", "suffix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map1",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithSuffixNamespace(cmap, "config-map1", "suffix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map1",
+						},
+					}),
+			}),
 			filter: resid.NewResIdWithSuffixNamespace(cmap, "config-map2", "suffix", "namespace"),
-			expected: ResMap{resid.NewResIdWithSuffixNamespace(cmap, "config-map1", "suffix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map1",
-					},
-				}),
-			},
+			expected: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithSuffixNamespace(cmap, "config-map1", "suffix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map1",
+						},
+					}),
+			}),
 		},
 		"same namespace, same prefix, same suffix": {
-			resMap: ResMap{resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map1", "prefix", "suffix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map1", "prefix", "suffix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 			filter: resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map2", "prefix", "suffix", "namespace"),
-			expected: ResMap{resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map1", "prefix", "suffix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			expected: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixSuffixNamespace(cmap, "config-map1", "prefix", "suffix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 		},
 		"filter by cluster-level Gvk": {
-			resMap: ResMap{resid.NewResIdWithPrefixNamespace(cmap, "config-map", "prefix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			resMap: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixNamespace(cmap, "config-map", "prefix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 			filter: resid.NewResId(gvk.Gvk{Kind: "ClusterRoleBinding"}, "cluster-role-binding"),
-			expected: ResMap{resid.NewResIdWithPrefixNamespace(cmap, "config-map", "prefix", "namespace"): rf.FromMap(
-				map[string]interface{}{
-					"apiVersion": "v1",
-					"kind":       "ConfigMap",
-					"metadata": map[string]interface{}{
-						"name": "config-map",
-					},
-				}),
-			},
+			expected: FromMap(map[resid.ResId]*resource.Resource{
+				resid.NewResIdWithPrefixNamespace(cmap, "config-map", "prefix", "namespace"): rf.FromMap(
+					map[string]interface{}{
+						"apiVersion": "v1",
+						"kind":       "ConfigMap",
+						"metadata": map[string]interface{}{
+							"name": "config-map",
+						},
+					}),
+			}),
 		},
 	}

 	for name, test := range tests {
 		test := test
 		t.Run(name, func(t *testing.T) {
-			got := test.resMap.FilterBy(test.filter)
-			if !reflect.DeepEqual(test.expected, got) {
+			got := test.resMap.ResourcesThatCouldReference(test.filter)
+			err := test.expected.ErrorIfNotEqual(got)
+			if err != nil {
 				t.Fatalf("Expected %v but got back %v", test.expected, got)
 			}
 		})
@@ -265,7 +393,7 @@ func TestFilterBy(t *testing.T) {
 }

 func TestDeepCopy(t *testing.T) {
-	rm1 := ResMap{
+	rm1 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -282,46 +410,63 @@ func TestDeepCopy(t *testing.T) {
 					"name": "cm2",
 				},
 			}),
-	}
+	})

-	rm2 := rm1.DeepCopy(rf)
+	rm2 := rm1.DeepCopy()

 	if &rm1 == &rm2 {
 		t.Fatal("DeepCopy returned a reference to itself instead of a copy")
 	}
-
-	if !reflect.DeepEqual(rm1, rm2) {
-		t.Fatalf("%v doesn't equal it's deep copy %v", rm1, rm2)
+	err := rm1.ErrorIfNotEqual(rm1)
+	if err != nil {
+		t.Fatal(err)
 	}
 }

 func TestGetMatchingIds(t *testing.T) {
-	// These ids used as map keys.
-	// They must be different to avoid overwriting
-	// map entries during construction.
-	ids := []resid.ResId{
+
+	m := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(
 			gvk.Gvk{Kind: "vegetable"},
-			"bedlam"),
+			"bedlam"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "ConfigMap",
+				"metadata": map[string]interface{}{
+					"name": "whatever1",
+				},
+			}),
 		resid.NewResId(
 			gvk.Gvk{Group: "g1", Version: "v1", Kind: "vegetable"},
-			"domino"),
+			"domino"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "ConfigMap",
+				"metadata": map[string]interface{}{
+					"name": "whatever2",
+				},
+			}),
 		resid.NewResIdWithPrefixNamespace(
 			gvk.Gvk{Kind: "vegetable"},
-			"peter", "p", "happy"),
+			"peter", "p", "happy"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "ConfigMap",
+				"metadata": map[string]interface{}{
+					"name": "whatever3",
+				},
+			}),
 		resid.NewResIdWithPrefixNamespace(
 			gvk.Gvk{Version: "v1", Kind: "fruit"},
-			"shatterstar", "p", "happy"),
-	}
-
-	m := ResMap{}
-	for _, id := range ids {
-		// Resources values don't matter in this test.
-		m[id] = nil
-	}
-	if len(m) != len(ids) {
-		t.Fatalf("unexpected map len %d presumably due to duplicate keys", len(m))
-	}
+			"shatterstar", "p", "happy"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "ConfigMap",
+				"metadata": map[string]interface{}{
+					"name": "whatever4",
+				},
+			}),
+	})

 	tests := []struct {
 		name    string
@@ -362,7 +507,7 @@ func TestGetMatchingIds(t *testing.T) {
 }

 func TestErrorIfNotEqual(t *testing.T) {
-	rm1 := ResMap{
+	rm1 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -379,14 +524,14 @@ func TestErrorIfNotEqual(t *testing.T) {
 					"name": "cm2",
 				},
 			}),
-	}
+	})

 	err := rm1.ErrorIfNotEqual(rm1)
 	if err != nil {
 		t.Fatalf("%v should equal itself %v", rm1, err)
 	}

-	rm2 := ResMap{
+	rm2 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -395,7 +540,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 					"name": "cm1",
 				},
 			}),
-	}
+	})

 	// test the different number of keys path
 	err = rm1.ErrorIfNotEqual(rm2)
@@ -403,7 +548,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 		t.Fatalf("%v should not equal %v %v", rm1, rm2, err)
 	}

-	rm3 := ResMap{
+	rm3 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm2"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -412,7 +557,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 					"name": "cm1",
 				},
 			}),
-	}
+	})

 	// test the different key values path
 	err = rm2.ErrorIfNotEqual(rm3)
@@ -420,7 +565,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 		t.Fatalf("%v should not equal %v %v", rm1, rm2, err)
 	}

-	rm4 := ResMap{
+	rm4 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cm1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "v1",
@@ -429,7 +574,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 					"name": "cm3",
 				},
 			}),
-	}
+	})

 	// test the deepcopy path
 	err = rm2.ErrorIfNotEqual(rm4)
@@ -440,7 +585,7 @@ func TestErrorIfNotEqual(t *testing.T) {
 }

 func TestMergeWithoutOverride(t *testing.T) {
-	input1 := ResMap{
+	input1 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(deploy, "deploy1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -449,8 +594,8 @@ func TestMergeWithoutOverride(t *testing.T) {
 					"name": "foo-deploy1",
 				},
 			}),
-	}
-	input2 := ResMap{
+	})
+	input2 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(statefulset, "stateful1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -459,9 +604,9 @@ func TestMergeWithoutOverride(t *testing.T) {
 					"name": "bar-stateful",
 				},
 			}),
-	}
+	})
 	input := []ResMap{input1, input2}
-	expected := ResMap{
+	expected := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(deploy, "deploy1"): rf.FromMap(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -478,12 +623,13 @@ func TestMergeWithoutOverride(t *testing.T) {
 					"name": "bar-stateful",
 				},
 			}),
-	}
+	})
 	merged, err := MergeWithErrorOnIdCollision(input...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged, expected) {
+	err = expected.ErrorIfNotEqual(merged)
+	if err != nil {
 		t.Fatalf("%#v doesn't equal expected %#v", merged, expected)
 	}
 	input3 := []ResMap{merged, nil}
@@ -491,21 +637,23 @@ func TestMergeWithoutOverride(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged1, expected) {
-		t.Fatalf("%#v doesn't equal expected %#v", merged1, expected)
+	err = expected.ErrorIfNotEqual(merged1)
+	if err != nil {
+		t.Fatal(err)
 	}
 	input4 := []ResMap{nil, merged}
 	merged2, err := MergeWithErrorOnIdCollision(input4...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged2, expected) {
-		t.Fatalf("%#v doesn't equal expected %#v", merged2, expected)
+	err = expected.ErrorIfNotEqual(merged2)
+	if err != nil {
+		t.Fatal(err)
 	}
 }

 func generateMergeFixtures(b types.GenerationBehavior) []ResMap {
-	input1 := ResMap{
+	input1 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cmap"): rf.FromMapAndOption(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -520,8 +668,8 @@ func generateMergeFixtures(b types.GenerationBehavior) []ResMap {
 			}, &types.GeneratorArgs{
 				Behavior: "create",
 			}, nil),
-	}
-	input2 := ResMap{
+	})
+	input2 := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cmap"): rf.FromMapAndOption(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -537,12 +685,12 @@ func generateMergeFixtures(b types.GenerationBehavior) []ResMap {
 			}, &types.GeneratorArgs{
 				Behavior: b.String(),
 			}, nil),
-	}
+	})
 	return []ResMap{input1, input2}
 }

 func TestMergeWithOverride(t *testing.T) {
-	expected := ResMap{
+	expected := FromMap(map[resid.ResId]*resource.Resource{
 		resid.NewResId(cmap, "cmap"): rf.FromMapAndOption(
 			map[string]interface{}{
 				"apiVersion": "apps/v1",
@@ -560,41 +708,43 @@ func TestMergeWithOverride(t *testing.T) {
 			}, &types.GeneratorArgs{
 				Behavior: "create",
 			}, nil),
-	}
+	})
 	merged, err := MergeWithOverride(generateMergeFixtures(types.BehaviorMerge)...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged, expected) {
-		t.Fatalf("%#v doesn't equal expected %#v", merged, expected)
+	err = expected.ErrorIfNotEqual(merged)
+	if err != nil {
+		t.Fatal(err)
 	}
 	input3 := []ResMap{merged, nil}
 	merged1, err := MergeWithOverride(input3...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged1, expected) {
-		t.Fatalf("%#v doesn't equal expected %#v", merged1, expected)
+	err = expected.ErrorIfNotEqual(merged1)
+	if err != nil {
+		t.Fatal(err)
 	}
 	input4 := []ResMap{nil, merged}
 	merged2, err := MergeWithOverride(input4...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if !reflect.DeepEqual(merged2, expected) {
-		t.Fatalf("%#v doesn't equal expected %#v", merged2, expected)
+	err = expected.ErrorIfNotEqual(merged2)
+	if err != nil {
+		t.Fatal(err)
 	}
-
 	inputs := generateMergeFixtures(types.BehaviorReplace)
 	replaced, err := MergeWithOverride(inputs...)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
 	expectedReplaced := inputs[1]
-	if !reflect.DeepEqual(replaced, expectedReplaced) {
-		t.Fatalf("%#v doesn't equal expected %#v", replaced, expectedReplaced)
+	err = expectedReplaced.ErrorIfNotEqual(replaced)
+	if err != nil {
+		t.Fatal(err)
 	}
-
 	_, err = MergeWithOverride(generateMergeFixtures(types.BehaviorUnspecified)...)
 	if err == nil {
 		t.Fatal("Merging with GenerationBehavior BehaviorUnspecified should return an error but does not")