add methods to allow filtering by gvk

go/fn/examples/example_filter_GVK_test.go

@@ -35,10 +35,9 @@ func updateReplicas(rl *fn.ResourceList) (bool, error) {
 	}
 	var replicas int
 	rl.FunctionConfig.GetOrDie(&replicas, "replicas")
-	for i, obj := range rl.Items {
-		if obj.IsGVK("apps/v1", "Deployment") {
-			rl.Items[i].SetOrDie(replicas, "spec", "replicas")
-		}
+	deployments := rl.Items.SelectByGvk("apps/v1", "Deployment")
+	for i := range deployments {
+		rl.Items[i].SetOrDie(replicas, "spec", "replicas")
 	}
 	return true, nil
 }

go/fn/examples/example_select_exclude_test.go

@@ -0,0 +1,23 @@
+package example
+
+import (
+	"os"
+
+	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn"
+)
+
+// This example implements a function that selectively includes or excludes some resources.
+
+func Example_selectExclude() {
+	if err := fn.AsMain(fn.ResourceListProcessorFunc(selectResources)); err != nil {
+		os.Exit(1)
+	}
+}
+
+// selectResources keeps all resources with the GVK apps/v1 Deployment that do
+// NOT have the label foo=bar, and removes the rest.
+func selectResources(rl *fn.ResourceList) (bool, error) {
+	rl.Items = rl.Items.SelectByGvk("apps/v1", "Deployment").
+		ExcludeByLabels(map[string]string{"foo": "bar"})
+	return true, nil
+}

go/fn/object.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"reflect"
 	"strconv"
+	"strings"
 
 	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn/internal"
 	"sigs.k8s.io/kustomize/kyaml/kio/kioutil"
@@ -690,6 +691,18 @@ func (o *KubeObject) GetAnnotation(k string) string {
 	return v
 }
 
+// HasAnnotations returns whether the KubeObject has the provided annotations
+func (o *KubeObject) HasAnnotations(annotations map[string]string) bool {
+	kubeObjectLabels := o.GetAnnotations()
+	for k, v := range annotations {
+		kubeObjectValue, found := kubeObjectLabels[k]
+		if !found || kubeObjectValue != v {
+			return false
+		}
+	}
+	return true
+}
+
 // RemoveAnnotationsIfEmpty removes the annotations field when it has zero annotations.
 func (o *KubeObject) RemoveAnnotationsIfEmpty() error {
 	annotations, found, err := o.obj.GetNestedStringMap("metadata", "annotations")
@@ -721,6 +734,18 @@ func (o *KubeObject) GetLabels() map[string]string {
 	return v
 }
 
+// HasLabels returns whether the KubeObject has the provided labels
+func (o *KubeObject) HasLabels(labels map[string]string) bool {
+	kubeObjectLabels := o.GetLabels()
+	for k, v := range labels {
+		kubeObjectValue, found := kubeObjectLabels[k]
+		if !found || kubeObjectValue != v {
+			return false
+		}
+	}
+	return true
+}
+
 func (o *KubeObject) PathAnnotation() string {
 	anno := o.GetAnnotation(kioutil.PathAnnotation)
 	return anno
@@ -759,6 +784,107 @@ func (o KubeObjects) Less(i, j int) bool {
 	return idStrI < idStrJ
 }
 
+func (o KubeObjects) String() string {
+	var elems []string
+	for _, obj := range o {
+		elems = append(elems, strings.TrimSpace(obj.String()))
+	}
+	return strings.Join(elems, "\n---\n")
+}
+
+// Select will return the subset of objects in KubeObjects such that f(object) returns 'true'.
+func (o KubeObjects) Select(f func(o *KubeObject) bool) KubeObjects {
+	var result KubeObjects
+	for _, obj := range o {
+		if f(obj) {
+			result = append(result, obj)
+		}
+	}
+	return result
+}
+
+// SelectByGvk will return the subset of objects that matches the provided GVK.
+func (o KubeObjects) SelectByGvk(apiVersion, kind string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.IsGVK(apiVersion, kind)
+	})
+}
+
+// ExcludeByGvk will return the subset of objects that do not match the provided GVK.
+func (o KubeObjects) ExcludeByGvk(apiVersion, kind string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return !o.IsGVK(apiVersion, kind)
+	})
+}
+
+// SelectByName will return the subset of objects that matches the provided name.
+func (o KubeObjects) SelectByName(name string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.GetName() == name
+	})
+}
+
+// ExcludeByName will return the subset of objects that do not match the provided name.
+func (o KubeObjects) ExcludeByName(name string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.GetName() != name
+	})
+}
+
+// SelectByNamespace will return the subset of objects that matches the provided namespace.
+func (o KubeObjects) SelectByNamespace(namespace string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.GetNamespace() == namespace
+	})
+}
+
+// ExcludeByNamespace will return the subset of objects that do not match the provided namespace.
+func (o KubeObjects) ExcludeByNamespace(namespace string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.GetNamespace() != namespace
+	})
+}
+
+// SelectByLabels will return the subset of objects that matches the provided labels.
+func (o KubeObjects) SelectByLabels(labels map[string]string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.HasLabels(labels)
+	})
+}
+
+// ExcludeByLabels will return the subset of objects that do not match the provided labels.
+func (o KubeObjects) ExcludeByLabels(labels map[string]string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return !o.HasLabels(labels)
+	})
+}
+
+// SelectByAnnotations will return the subset of objects that matches the provided labels.
+func (o KubeObjects) SelectByAnnotations(annotations map[string]string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return o.HasAnnotations(annotations)
+	})
+}
+
+// ExcludeByAnnotations will return the subset of objects that do not match the provided labels.
+func (o KubeObjects) ExcludeByAnnotations(annotations map[string]string) KubeObjects {
+	return o.Select(func(o *KubeObject) bool {
+		return !o.HasAnnotations(annotations)
+	})
+}
+
+// SelectMetaResources will return the subset of objects that are meta resources. Currently, this
+// is just the Kptfile.
+func (o KubeObjects) SelectMetaResources() KubeObjects {
+	return o.SelectByGvk("kpt.dev/v1", "Kptfile")
+}
+
+// ExcludeMetaResources will return the subset of objects that are not meta resources. Currently, this
+// is just the Kptfile.
+func (o KubeObjects) ExcludeMetaResources() KubeObjects {
+	return o.ExcludeByGvk("kpt.dev/v1", "Kptfile")
+}
+
 func (o *KubeObject) IsEmpty() bool {
 	return yaml.IsYNodeEmptyMap(o.obj.Node())
 }

go/fn/object_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestIsNamespaceScoped(t *testing.T) {
@@ -284,3 +285,148 @@ func TestGetMap(t *testing.T) {
 		t.Errorf("unexpected value for GetMap(%q); got %v, want nil", "notExists", got)
 	}
 }
+
+func TestSelectors(t *testing.T) {
+	deployment := `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo
+`
+	service := `
+apiVersion: apps/v1
+kind: Service
+metadata:
+  name: example
+  namespace: my-namespace
+  labels:
+    foo: baz
+  annotations:
+    foo: bar
+`
+	d, err := ParseKubeObject([]byte(deployment))
+	assert.NoError(t, err)
+	s, err := ParseKubeObject([]byte(service))
+	assert.NoError(t, err)
+	input := KubeObjects{d, s}
+
+	// select all resources with labels foo=baz
+	items := input.SelectByLabels(map[string]string{"foo": "baz"})
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo
+---
+apiVersion: apps/v1
+kind: Service
+metadata:
+  name: example
+  namespace: my-namespace
+  labels:
+    foo: baz
+  annotations:
+    foo: bar`)
+
+	// select all deployments
+	items = input.SelectByGvk("apps/v1", "Deployment")
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo`)
+
+	// exclude all services
+	items = input.ExcludeByGvk("apps/v1", "Service")
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo`)
+
+	// include resources with the label abc: def
+	items = input.SelectByLabels(map[string]string{"abc": "def"})
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo`)
+
+	// exclude all resources with the annotation foo=bar
+	items = input.ExcludeByAnnotations(map[string]string{"foo": "bar"})
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+  annotations:
+    bar: foo`)
+
+	// include resources named 'example' that are Not in namespace default
+	items = input.SelectByName("example").ExcludeByNamespace("default")
+	assert.Equal(t, items.String(), `apiVersion: apps/v1
+kind: Service
+metadata:
+  name: example
+  namespace: my-namespace
+  labels:
+    foo: baz
+  annotations:
+    foo: bar`)
+
+	// add the label "g=h" to all resources with annotation "bar=foo"
+	items = input.SelectByAnnotations(map[string]string{"bar": "foo"})
+	for _, obj := range items {
+		obj.SetLabel("g", "h")
+	}
+	assert.Equal(t, input.String(), `apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: example
+  namespace: default
+  labels:
+    abc: def
+    foo: baz
+    g: h
+  annotations:
+    bar: foo
+---
+apiVersion: apps/v1
+kind: Service
+metadata:
+  name: example
+  namespace: my-namespace
+  labels:
+    foo: baz
+  annotations:
+    foo: bar`)
+}

go/fn/resourcelist.go

@@ -33,7 +33,7 @@ type ResourceList struct {
 	// Items will be a slice containing the Deployment and Service resources
 	// Mutating functions will alter this field during processing.
 	// This field is required.
-	Items []*KubeObject `yaml:"items" json:"items"`
+	Items KubeObjects `yaml:"items" json:"items"`
 
 	// FunctionConfig is the ResourceList.functionConfig input value.
 	//
@@ -178,7 +178,7 @@ func (rl *ResourceList) ToYAML() ([]byte, error) {
 
 // Sort sorts the ResourceList.items by apiVersion, kind, namespace and name.
 func (rl *ResourceList) Sort() {
-	sort.Sort(KubeObjects(rl.Items))
+	sort.Sort(rl.Items)
 }
 
 // UpsertObjectToItems adds an object to ResourceList.items. The input object can