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,
+	})
+}

pkg/framework/fake/plugin/fixture.go

@@ -0,0 +1,135 @@
+/*
+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 (
+	v1 "k8s.io/api/core/v1"
+	"sigs.k8s.io/descheduler/pkg/framework"
+)
+
+type Action interface {
+	Handle() framework.Handle
+	GetExtensionPoint() string
+	DeepCopy() Action
+}
+
+// Reactor is an interface to allow the composition of reaction functions.
+type Reactor interface {
+	// Handles indicates whether or not this Reactor deals with a given
+	// action.
+	Handles(action Action) bool
+	// React handles the action.  It may choose to
+	// delegate by indicated handled=false.
+	React(action Action) (handled bool, err error)
+}
+
+// SimpleReactor is a Reactor. Each reaction function is attached to a given extensionPoint. "*" in either field matches everything for that value.
+type SimpleReactor struct {
+	ExtensionPoint string
+	Reaction       ReactionFunc
+}
+
+func (r *SimpleReactor) Handles(action Action) bool {
+	return r.ExtensionPoint == "*" || r.ExtensionPoint == action.GetExtensionPoint()
+}
+
+func (r *SimpleReactor) React(action Action) (bool, error) {
+	return r.Reaction(action)
+}
+
+type ReactionFunc func(action Action) (handled bool, err error)
+
+type DescheduleAction interface {
+	Action
+	CanDeschedule() bool
+	Nodes() []*v1.Node
+}
+
+type BalanceAction interface {
+	Action
+	CanBalance() bool
+	Nodes() []*v1.Node
+}
+
+type ActionImpl struct {
+	handle         framework.Handle
+	extensionPoint string
+}
+
+func (a ActionImpl) Handle() framework.Handle {
+	return a.handle
+}
+
+func (a ActionImpl) GetExtensionPoint() string {
+	return a.extensionPoint
+}
+
+func (a ActionImpl) DeepCopy() Action {
+	// The handle is expected to be accessed only throuh interface methods
+	// Thus, no deep copy needed.
+	ret := a
+	return ret
+}
+
+type DescheduleActionImpl struct {
+	ActionImpl
+	nodes []*v1.Node
+}
+
+func (d DescheduleActionImpl) CanDeschedule() bool {
+	return true
+}
+
+func (d DescheduleActionImpl) Nodes() []*v1.Node {
+	return d.nodes
+}
+
+func (a DescheduleActionImpl) DeepCopy() Action {
+	nodesCopy := []*v1.Node{}
+	for _, node := range a.nodes {
+		nodesCopy = append(nodesCopy, node.DeepCopy())
+	}
+	return DescheduleActionImpl{
+		ActionImpl: a.ActionImpl.DeepCopy().(ActionImpl),
+		nodes:      nodesCopy,
+	}
+}
+
+type BalanceActionImpl struct {
+	ActionImpl
+	nodes []*v1.Node
+}
+
+func (d BalanceActionImpl) CanBalance() bool {
+	return true
+}
+
+func (d BalanceActionImpl) Nodes() []*v1.Node {
+	return d.nodes
+}
+
+func (a BalanceActionImpl) DeepCopy() Action {
+	nodesCopy := []*v1.Node{}
+	for _, node := range a.nodes {
+		nodesCopy = append(nodesCopy, node.DeepCopy())
+	}
+	return BalanceActionImpl{
+		ActionImpl: a.ActionImpl.DeepCopy().(ActionImpl),
+		nodes:      nodesCopy,
+	}
+}
+
+func (c *FakePlugin) AddReactor(extensionPoint string, reaction ReactionFunc) {
+	c.ReactionChain = append(c.ReactionChain, &SimpleReactor{ExtensionPoint: extensionPoint, Reaction: reaction})
+}

pkg/framework/fake/plugin/zz_generated.deepcopy.go

@@ -0,0 +1,51 @@
+//go:build !ignore_autogenerated
+// +build !ignore_autogenerated
+
+/*
+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.
+*/
+
+// Code generated by deepcopy-gen. DO NOT EDIT.
+
+package plugin
+
+import (
+	runtime "k8s.io/apimachinery/pkg/runtime"
+)
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *FakePluginArgs) DeepCopyInto(out *FakePluginArgs) {
+	*out = *in
+	out.TypeMeta = in.TypeMeta
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new FakePluginArgs.
+func (in *FakePluginArgs) DeepCopy() *FakePluginArgs {
+	if in == nil {
+		return nil
+	}
+	out := new(FakePluginArgs)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyObject is an autogenerated deepcopy function, copying the receiver, creating a new runtime.Object.
+func (in *FakePluginArgs) DeepCopyObject() runtime.Object {
+	if c := in.DeepCopy(); c != nil {
+		return c
+	}
+	return nil
+}