Add CreateOrUpdate utility method

pkg/controller/controllerutil/controllerutil.go

@@ -17,11 +17,15 @@ limitations under the License.
 package controllerutil
 
 import (
+	"context"
 	"fmt"
+	"reflect"
 
+	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
 )
 
@@ -97,3 +101,78 @@ func referSameObject(a, b v1.OwnerReference) bool {
 
 	return aGV == bGV && a.Kind == b.Kind && a.Name == b.Name
 }
+
+// OperationResult is the action result of a CreateOrUpdate call
+type OperationResult string
+
+const ( // They should complete the sentence "Deployment default/foo has been ..."
+	// OperationResultNone means that the resource has not been changed
+	OperationResultNone OperationResult = "unchanged"
+	// OperationResultCreated means that a new resource is created
+	OperationResultCreated OperationResult = "created"
+	// OperationResultUpdated means that an existing resource is updated
+	OperationResultUpdated OperationResult = "updated"
+)
+
+// CreateOrUpdate creates or updates the given object obj in the Kubernetes
+// cluster. The object's desired state should be reconciled with the existing
+// state using the passed in ReconcileFn. obj must be a struct pointer so that
+// obj can be updated with the content returned by the Server.
+//
+// It returns the executed operation and an error.
+func CreateOrUpdate(ctx context.Context, c client.Client, obj runtime.Object, f MutateFn) (OperationResult, error) {
+	// op is the operation we are going to attempt
+	op := OperationResultNone
+
+	// get the existing object meta
+	metaObj, ok := obj.(v1.Object)
+	if !ok {
+		return OperationResultNone, fmt.Errorf("%T does not implement metav1.Object interface", obj)
+	}
+
+	// retrieve the existing object
+	key := client.ObjectKey{
+		Name:      metaObj.GetName(),
+		Namespace: metaObj.GetNamespace(),
+	}
+	err := c.Get(ctx, key, obj)
+
+	// reconcile the existing object
+	existing := obj.DeepCopyObject()
+	existingObjMeta := existing.(v1.Object)
+	existingObjMeta.SetName(metaObj.GetName())
+	existingObjMeta.SetNamespace(metaObj.GetNamespace())
+
+	if e := f(obj); e != nil {
+		return OperationResultNone, e
+	}
+
+	if metaObj.GetName() != existingObjMeta.GetName() {
+		return OperationResultNone, fmt.Errorf("ReconcileFn cannot mutate objects name")
+	}
+
+	if metaObj.GetNamespace() != existingObjMeta.GetNamespace() {
+		return OperationResultNone, fmt.Errorf("ReconcileFn cannot mutate objects namespace")
+	}
+
+	if errors.IsNotFound(err) {
+		err = c.Create(ctx, obj)
+		op = OperationResultCreated
+	} else if err == nil {
+		if reflect.DeepEqual(existing, obj) {
+			return OperationResultNone, nil
+		}
+		err = c.Update(ctx, obj)
+		op = OperationResultUpdated
+	} else {
+		return OperationResultNone, err
+	}
+
+	if err != nil {
+		op = OperationResultNone
+	}
+	return op, err
+}
+
+// MutateFn is a function which mutates the existing object into it's desired state.
+type MutateFn func(existing runtime.Object) error

pkg/controller/controllerutil/controllerutil_suite_test.go

@@ -21,9 +21,33 @@ import (
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+
+	"k8s.io/client-go/rest"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/envtest"
 )
 
 func TestControllerutil(t *testing.T) {
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "Controllerutil Suite")
 }
+
+var t *envtest.Environment
+var cfg *rest.Config
+var c client.Client
+
+var _ = BeforeSuite(func() {
+	var err error
+
+	t = &envtest.Environment{}
+
+	cfg, err = t.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	c, err = client.New(cfg, client.Options{})
+	Expect(err).NotTo(HaveOccurred())
+})
+
+var _ = AfterSuite(func() {
+	t.Stop()
+})

pkg/controller/controllerutil/controllerutil_test.go

@@ -17,12 +17,18 @@ limitations under the License.
 package controllerutil_test
 
 import (
+	"context"
+	"fmt"
+	"math/rand"
+
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	appsv1 "k8s.io/api/apps/v1"
+	corev1 "k8s.io/api/core/v1"
 	extensionsv1beta1 "k8s.io/api/extensions/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes/scheme"
 	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 )
@@ -108,10 +114,162 @@ var _ = Describe("Controllerutil", func() {
 			}))
 		})
 	})
+
+	Describe("CreateOrUpdate", func() {
+		var deploy *appsv1.Deployment
+		var deplSpec appsv1.DeploymentSpec
+		var deplKey types.NamespacedName
+
+		BeforeEach(func() {
+			deploy = &appsv1.Deployment{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      fmt.Sprintf("deploy-%d", rand.Int31()),
+					Namespace: "default",
+				},
+			}
+
+			deplSpec = appsv1.DeploymentSpec{
+				Selector: &metav1.LabelSelector{
+					MatchLabels: map[string]string{"foo": "bar"},
+				},
+				Template: corev1.PodTemplateSpec{
+					ObjectMeta: metav1.ObjectMeta{
+						Labels: map[string]string{
+							"foo": "bar",
+						},
+					},
+					Spec: corev1.PodSpec{
+						Containers: []corev1.Container{
+							corev1.Container{
+								Name:  "busybox",
+								Image: "busybox",
+							},
+						},
+					},
+				},
+			}
+
+			deplKey = types.NamespacedName{
+				Name:      deploy.Name,
+				Namespace: deploy.Namespace,
+			}
+		})
+
+		It("creates a new object if one doesn't exists", func() {
+			op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentSpecr(deplSpec))
+
+			By("returning OperationResultCreatedd")
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultCreated))
+
+			By("returning no error")
+			Expect(err).NotTo(HaveOccurred())
+
+			By("actually having the deployment created")
+			fetched := &appsv1.Deployment{}
+			Expect(c.Get(context.TODO(), deplKey, fetched)).To(Succeed())
+		})
+
+		It("updates existing object", func() {
+			var scale int32 = 2
+			op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentSpecr(deplSpec))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultCreated))
+
+			op, err = controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentScaler(scale))
+			By("returning OperationResultUpdatedd")
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultUpdated))
+
+			By("returning no error")
+			Expect(err).NotTo(HaveOccurred())
+
+			By("actually having the deployment scaled")
+			fetched := &appsv1.Deployment{}
+			Expect(c.Get(context.TODO(), deplKey, fetched)).To(Succeed())
+			Expect(*fetched.Spec.Replicas).To(Equal(scale))
+		})
+
+		It("updates only changed objects", func() {
+			op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentSpecr(deplSpec))
+
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultCreated))
+			Expect(err).NotTo(HaveOccurred())
+
+			op, err = controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentIdentity)
+
+			By("returning OperationResultNone")
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultNone))
+
+			By("returning no error")
+			Expect(err).NotTo(HaveOccurred())
+		})
+
+		It("errors when reconcile renames an object", func() {
+			op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentSpecr(deplSpec))
+
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultCreated))
+			Expect(err).NotTo(HaveOccurred())
+
+			op, err = controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentRenamer)
+
+			By("returning OperationResultNone")
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultNone))
+
+			By("returning error")
+			Expect(err).To(HaveOccurred())
+		})
+
+		It("errors when object namespace changes", func() {
+			op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentSpecr(deplSpec))
+
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultCreated))
+			Expect(err).NotTo(HaveOccurred())
+
+			op, err = controllerutil.CreateOrUpdate(context.TODO(), c, deploy, deploymentNamespaceChanger)
+
+			By("returning OperationResultNone")
+			Expect(op).To(BeEquivalentTo(controllerutil.OperationResultNone))
+
+			By("returning error")
+			Expect(err).To(HaveOccurred())
+		})
+	})
 })
 
 var _ metav1.Object = &errMetaObj{}
 
 type errMetaObj struct {
 	metav1.ObjectMeta
 }
+
+func deploymentSpecr(spec appsv1.DeploymentSpec) controllerutil.MutateFn {
+	return func(obj runtime.Object) error {
+		deploy := obj.(*appsv1.Deployment)
+		deploy.Spec = spec
+		return nil
+	}
+}
+
+var deploymentIdentity controllerutil.MutateFn = func(obj runtime.Object) error {
+	return nil
+}
+
+var deploymentRenamer controllerutil.MutateFn = func(obj runtime.Object) error {
+	deploy := obj.(*appsv1.Deployment)
+	deploy.Name = fmt.Sprintf("%s-1", deploy.Name)
+	return nil
+}
+
+var deploymentNamespaceChanger controllerutil.MutateFn = func(obj runtime.Object) error {
+	deploy := obj.(*appsv1.Deployment)
+	deploy.Namespace = fmt.Sprintf("%s-1", deploy.Namespace)
+	return nil
+}
+
+func deploymentScaler(replicas int32) controllerutil.MutateFn {
+	fn := func(obj runtime.Object) error {
+		deploy := obj.(*appsv1.Deployment)
+		deploy.Spec.Replicas = &replicas
+		return nil
+	}
+	return fn
+}

pkg/controller/controllerutil/example_test.go

@@ -0,0 +1,78 @@
+/*
+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 controllerutil_test
+
+import (
+	"context"
+
+	appsv1 "k8s.io/api/apps/v1"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+
+	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
+	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"
+)
+
+var (
+	log = logf.Log.WithName("controllerutil-examples")
+)
+
+// This example creates or updates an existing deployment
+func ExampleCreateOrUpdate() {
+	// c is client.Client
+
+	// Create or Update the deployment default/foo
+	deployment := &appsv1.Deployment{ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: "default"}}
+
+	op, err := controllerutil.CreateOrUpdate(context.TODO(), c, deployment, func(existing runtime.Object) error {
+		deploy := existing.(*appsv1.Deployment)
+
+		// Deployment selector is immutable so we set this value only if
+		// a new object is going to be created
+		if deploy.ObjectMeta.CreationTimestamp.IsZero() {
+			deploy.Spec.Selector = &metav1.LabelSelector{
+				MatchLabels: map[string]string{"foo": "bar"},
+			}
+		}
+
+		// update the Deployment pod template
+		deploy.Spec.Template = corev1.PodTemplateSpec{
+			ObjectMeta: metav1.ObjectMeta{
+				Labels: map[string]string{
+					"foo": "bar",
+				},
+			},
+			Spec: corev1.PodSpec{
+				Containers: []corev1.Container{
+					corev1.Container{
+						Name:  "busybox",
+						Image: "busybox",
+					},
+				},
+			},
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		log.Error(err, "Deployment reconcile failed")
+	} else {
+		log.Info("Deployment successfully reconciled", "operation", op)
+	}
+}