Descheduling profile with PoC fake plugin (#1093)

* Descheduling profile

* Fake plugin + profile unit testing

* Rename Profile config type into DeschedulerProfile

To avoid resamblance with profileImpl

* First run deschedule, then balance extension points

pkg/framework/fake/plugin/fake.go

@@ -0,0 +1,138 @@
+/*
+Copyright 2023 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 plugin
+
+import (
+	"context"
+	"fmt"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/descheduler/pkg/framework"
+	"sigs.k8s.io/descheduler/pkg/framework/pluginregistry"
+)
+
+// +k8s:deepcopy-gen=true
+// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
+
+// FakePluginArgs holds arguments used to configure FakePlugin plugin.
+type FakePluginArgs struct {
+	metav1.TypeMeta `json:",inline"`
+}
+
+func ValidateFakePluginArgs(obj runtime.Object) error {
+	return nil
+}
+
+func SetDefaults_FakePluginArgs(obj runtime.Object) {}
+
+var (
+	_ framework.EvictorPlugin    = &FakePlugin{}
+	_ framework.DeschedulePlugin = &FakePlugin{}
+	_ framework.BalancePlugin    = &FakePlugin{}
+)
+
+// FakePlugin is a configurable plugin used for testing
+type FakePlugin struct {
+	PluginName string
+
+	// ReactionChain is the list of reactors that will be attempted for every
+	// request in the order they are tried.
+	ReactionChain []Reactor
+
+	args   runtime.Object
+	handle framework.Handle
+}
+
+func NewPluginFncFromFake(fp *FakePlugin) pluginregistry.PluginBuilder {
+	return func(args runtime.Object, handle framework.Handle) (framework.Plugin, error) {
+		fakePluginArgs, ok := args.(*FakePluginArgs)
+		if !ok {
+			return nil, fmt.Errorf("want args to be of type FakePluginArgs, got %T", args)
+		}
+
+		fp.handle = handle
+		fp.args = fakePluginArgs
+
+		return fp, nil
+	}
+}
+
+// New builds plugin from its arguments while passing a handle
+func New(args runtime.Object, handle framework.Handle) (framework.Plugin, error) {
+	fakePluginArgs, ok := args.(*FakePluginArgs)
+	if !ok {
+		return nil, fmt.Errorf("want args to be of type FakePluginArgs, got %T", args)
+	}
+
+	ev := &FakePlugin{}
+	ev.handle = handle
+	ev.args = fakePluginArgs
+
+	return ev, nil
+}
+
+// Name retrieves the plugin name
+func (d *FakePlugin) Name() string {
+	return d.PluginName
+}
+
+func (d *FakePlugin) PreEvictionFilter(pod *v1.Pod) bool {
+	return true
+}
+
+func (d *FakePlugin) Filter(pod *v1.Pod) bool {
+	return true
+}
+
+func (d *FakePlugin) handleAction(action Action) *framework.Status {
+	actionCopy := action.DeepCopy()
+	for _, reactor := range d.ReactionChain {
+		if !reactor.Handles(actionCopy) {
+			continue
+		}
+		handled, err := reactor.React(actionCopy)
+		if !handled {
+			continue
+		}
+
+		return &framework.Status{
+			Err: err,
+		}
+	}
+	return &framework.Status{
+		Err: fmt.Errorf("unhandled %q action", action.GetExtensionPoint()),
+	}
+}
+
+func (d *FakePlugin) Deschedule(ctx context.Context, nodes []*v1.Node) *framework.Status {
+	return d.handleAction(&DescheduleActionImpl{
+		ActionImpl: ActionImpl{
+			handle:         d.handle,
+			extensionPoint: string(framework.DescheduleExtensionPoint),
+		},
+		nodes: nodes,
+	})
+}
+
+func (d *FakePlugin) Balance(ctx context.Context, nodes []*v1.Node) *framework.Status {
+	return d.handleAction(&BalanceActionImpl{
+		ActionImpl: ActionImpl{
+			handle:         d.handle,
+			extensionPoint: string(framework.BalanceExtensionPoint),
+		},
+		nodes: nodes,
+	})
+}