runtime/patcher: Add SerialPatcher

SerialPatcher is a wrapper around the patch helper to help perform
consecutive patching of object in a transparent manner without the need
to keep track of the object state after patching.

The SerialPatcher persists the a before state of the object and a
kubernetes client. The patch operations configurations aren't persisted
and are accepted as argument to SerialPatcher.Patch(). This makes the
patcher reusable in different scenarios during its lifetime.

Signed-off-by: Sunny <darkowlzz@protonmail.com>

runtime/patch/serial.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2022 The Flux 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 patch
+
+import (
+	"context"
+
+	kerrors "k8s.io/apimachinery/pkg/util/errors"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+// SerialPatcher provides serial patching of object using the patch helper. It
+// remembers the state of the last patched object and uses that to calculate
+// the patch aginst a new object.
+type SerialPatcher struct {
+	client       client.Client
+	beforeObject client.Object
+}
+
+// serialPatchOptions are the serial patch options used in configuring the
+// patch operation of SerialPatcher. These are not persisted on the
+// SerialPatcher and are defined per patch operation.
+type serialPatchOptions struct {
+	patchOpts  []Option
+	errFilters []kerrors.Matcher
+}
+
+// SerialPatcherOption is option that configures the SerialPatcher.
+type SerialPatchOption func(*serialPatchOptions)
+
+// WithSerialPatchOptions sets the patch options for a patch operation.
+func WithSerialPatchOptions(opts ...Option) SerialPatchOption {
+	return func(spo *serialPatchOptions) {
+		spo.patchOpts = append(spo.patchOpts, opts...)
+	}
+}
+
+// WithSerialPatchErrorFilters sets the error filter out matchers for a patch
+// operation.
+func WithSerialPatchErrorFilters(matchers ...kerrors.Matcher) SerialPatchOption {
+	return func(spo *serialPatchOptions) {
+		spo.errFilters = append(spo.errFilters, matchers...)
+	}
+}
+
+// NewSerialPatcher returns a SerialPatcher with the given object as the initial
+// base object for the patching operations.
+func NewSerialPatcher(obj client.Object, c client.Client) *SerialPatcher {
+	return &SerialPatcher{
+		client:       c,
+		beforeObject: obj.DeepCopyObject().(client.Object),
+	}
+}
+
+// Patch performs patching operation of the SerialPatcher and updates the
+// beforeObject after a successful patch for subsequent patching.
+func (sp *SerialPatcher) Patch(ctx context.Context, obj client.Object, options ...SerialPatchOption) error {
+	// Create a new patch helper with the before object.
+	patcher, err := NewHelper(sp.beforeObject, sp.client)
+	if err != nil {
+		return err
+	}
+
+	// Configure the patch options.
+	spOpts := &serialPatchOptions{}
+	for _, o := range options {
+		o(spOpts)
+	}
+
+	// Patch with the changes from the new object.
+	if err := patcher.Patch(ctx, obj, spOpts.patchOpts...); err != nil {
+		err = kerrors.FilterOut(err, spOpts.errFilters...)
+		return err
+	}
+
+	// Update the before object for next patch.
+	sp.beforeObject = obj.DeepCopyObject().(client.Object)
+
+	return nil
+}

runtime/patch/serial_test.go

@@ -0,0 +1,162 @@
+/*
+Copyright 2022 The Flux 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 patch
+
+import (
+	"reflect"
+	"testing"
+
+	. "github.com/onsi/gomega"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
+
+	"github.com/fluxcd/pkg/apis/meta"
+	"github.com/fluxcd/pkg/runtime/conditions"
+	"github.com/fluxcd/pkg/runtime/conditions/testdata"
+)
+
+func TestSerialPatcher(t *testing.T) {
+	t.Run("should be able to patch object consecutively", func(t *testing.T) {
+		g := NewWithT(t)
+
+		testFinalizer := "test.finalizer.flux.io"
+		obj := &testdata.Fake{
+			ObjectMeta: metav1.ObjectMeta{
+				GenerateName: "test-",
+				Namespace:    "default",
+			},
+		}
+
+		ownedConditions := []string{
+			meta.ReadyCondition,
+			meta.ReconcilingCondition,
+			meta.StalledCondition,
+		}
+
+		t.Log("Creating the object")
+		g.Expect(env.Create(ctx, obj)).To(Succeed())
+		defer func() {
+			err := env.Delete(ctx, obj)
+			g.Expect(client.IgnoreNotFound(err)).ToNot(HaveOccurred())
+		}()
+		key := client.ObjectKeyFromObject(obj)
+
+		t.Log("Checking that the object has been created")
+		g.Eventually(func() error {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return err
+			}
+			return nil
+		}).Should(Succeed())
+
+		t.Log("Creating a new serial patcher")
+		patcher := NewSerialPatcher(obj, env.Client)
+
+		t.Log("Add a finalizer")
+		controllerutil.AddFinalizer(obj, testFinalizer)
+
+		t.Log("Patching the object")
+		g.Expect(patcher.Patch(ctx, obj)).To(Succeed())
+
+		t.Log("Validating that the finalizer is added")
+		g.Eventually(func() bool {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return false
+			}
+			return reflect.DeepEqual(obj.Finalizers, objAfter.Finalizers)
+		}, timeout).Should(BeTrue())
+
+		t.Log("Add status condition")
+		conditions.MarkReconciling(obj, "reason", "")
+		conditions.MarkFalse(obj, meta.ReadyCondition, "reason", "")
+
+		t.Log("Patch the object")
+		patchOpts := []Option{
+			WithOwnedConditions{ownedConditions},
+		}
+		g.Expect(patcher.Patch(ctx, obj, WithSerialPatchOptions(patchOpts...)))
+
+		t.Log("Validating that the conditions are added")
+		g.Eventually(func() bool {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return false
+			}
+			return !conditions.IsReady(objAfter) && conditions.IsReconciling(objAfter)
+		}, timeout).Should(BeTrue())
+
+		t.Log("Remove and update conditions")
+		conditions.Delete(obj, meta.ReconcilingCondition)
+		conditions.MarkTrue(obj, meta.ReadyCondition, "reason", "")
+
+		t.Log("Patch the object")
+		g.Expect(patcher.Patch(ctx, obj, WithSerialPatchOptions(patchOpts...)))
+
+		t.Log("Validating that the conditions are updated")
+		g.Eventually(func() bool {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return false
+			}
+			return conditions.IsReady(objAfter) && !conditions.IsReconciling(objAfter)
+		})
+
+		t.Log("Remove finalizer")
+		controllerutil.RemoveFinalizer(obj, testFinalizer)
+
+		t.Log("Patch the object")
+		g.Expect(patcher.Patch(ctx, obj)).To(Succeed())
+
+		t.Log("Validating that the finalizer is removed")
+		g.Eventually(func() bool {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return false
+			}
+			return len(objAfter.Finalizers) == 0
+		}, timeout).Should(BeTrue())
+
+		t.Log("Delete object")
+		g.Expect(env.Delete(ctx, obj)).To(Succeed())
+		g.Eventually(func() bool {
+			objAfter := obj.DeepCopy()
+			if err := env.Get(ctx, key, objAfter); err != nil {
+				return apierrors.IsNotFound(err)
+			}
+			return false
+		}, timeout).Should(BeTrue())
+
+		t.Log("Update deleted object")
+		conditions.MarkReconciling(obj, "reason", "")
+
+		t.Log("Patch deleted object")
+		g.Expect(patcher.Patch(ctx, obj, WithSerialPatchOptions(patchOpts...))).ToNot(Succeed())
+
+		filterNotFound := func(e error) bool {
+			return apierrors.IsNotFound(e)
+		}
+		t.Log("Patch deleted object with ignore not found")
+		g.Expect(patcher.Patch(ctx, obj,
+			WithSerialPatchOptions(patchOpts...),
+			WithSerialPatchErrorFilters(filterNotFound),
+		)).To(Succeed())
+	})
+}