feat: add the sameplacementaffinity plugin (filtering) (#449)

pkg/scheduler/framework/plugins/sameplacementaffinity/filtering.go

@@ -0,0 +1,29 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package sameplacementaffinity
+
+import (
+	"context"
+
+	fleetv1beta1 "go.goms.io/fleet/apis/placement/v1beta1"
+	"go.goms.io/fleet/pkg/scheduler/framework"
+)
+
+// Filter allows the plugin to connect to the Filter extension point in the scheduling framework.
+func (p *Plugin) Filter(
+	_ context.Context,
+	state framework.CycleStatePluginReadWriter,
+	_ *fleetv1beta1.ClusterSchedulingPolicySnapshot,
+	cluster *fleetv1beta1.MemberCluster,
+) (status *framework.Status) {
+	if !state.HasScheduledOrBoundBindingFor(cluster.Name) {
+		// all done.
+		return nil
+	}
+
+	reason := "resource placement has already been scheduled or bounded on the cluster"
+	return framework.NewNonErrorStatus(framework.ClusterUnschedulable, p.Name(), reason)
+}

pkg/scheduler/framework/plugins/sameplacementaffinity/filtering_test.go

@@ -0,0 +1,113 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+package sameplacementaffinity
+
+import (
+	"context"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	fleetv1beta1 "go.goms.io/fleet/apis/placement/v1beta1"
+	"go.goms.io/fleet/pkg/scheduler/framework"
+)
+
+const (
+	clusterName = "member-1"
+)
+
+var (
+	cmpStatusOptions = cmp.Options{
+		cmpopts.IgnoreFields(framework.Status{}, "reasons", "err"),
+		cmp.AllowUnexported(framework.Status{}),
+	}
+	defaultPluginName = defaultPluginOptions.name
+)
+
+func TestFilter(t *testing.T) {
+	tests := []struct {
+		name                     string
+		scheduledOrBoundBindings []*fleetv1beta1.ClusterResourceBinding
+		want                     *framework.Status
+	}{
+		{
+			name: "placement has already been scheduled",
+			scheduledOrBoundBindings: []*fleetv1beta1.ClusterResourceBinding{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "binding1",
+					},
+					Spec: fleetv1beta1.ResourceBindingSpec{
+						TargetCluster: clusterName,
+						State:         fleetv1beta1.BindingStateScheduled,
+					},
+				},
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "binding2",
+					},
+					Spec: fleetv1beta1.ResourceBindingSpec{
+						TargetCluster: "another-cluster",
+						State:         fleetv1beta1.BindingStateScheduled,
+					},
+				},
+			},
+			want: framework.NewNonErrorStatus(framework.ClusterUnschedulable, defaultPluginName),
+		},
+		{
+			name: "placement has already been bounded",
+			scheduledOrBoundBindings: []*fleetv1beta1.ClusterResourceBinding{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "binding1",
+					},
+					Spec: fleetv1beta1.ResourceBindingSpec{
+						TargetCluster: clusterName,
+						State:         fleetv1beta1.BindingStateBound,
+					},
+				},
+			},
+			want: framework.NewNonErrorStatus(framework.ClusterUnschedulable, defaultPluginName),
+		},
+		{
+			name:                     "no bindings",
+			scheduledOrBoundBindings: []*fleetv1beta1.ClusterResourceBinding{},
+			want:                     nil,
+		},
+		{
+			name: "placement has been bounded/scheduled on other cluster",
+			scheduledOrBoundBindings: []*fleetv1beta1.ClusterResourceBinding{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: "binding1",
+					},
+					Spec: fleetv1beta1.ResourceBindingSpec{
+						TargetCluster: "another-cluster",
+						State:         fleetv1beta1.BindingStateBound,
+					},
+				},
+			},
+			want: nil,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			p := New()
+			state := framework.NewCycleState(nil, nil, tc.scheduledOrBoundBindings)
+			cluster := fleetv1beta1.MemberCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: clusterName,
+				},
+			}
+			got := p.Filter(context.Background(), state, nil, &cluster)
+			if diff := cmp.Diff(tc.want, got, cmpStatusOptions); diff != "" {
+				t.Errorf("Filter() status mismatch (-want, +got):\n%s", diff)
+			}
+		})
+	}
+}

pkg/scheduler/framework/plugins/sameplacementaffinity/plugin.go

@@ -0,0 +1,77 @@
+/*
+Copyright (c) Microsoft Corporation.
+Licensed under the MIT license.
+*/
+
+// Package sameplacementaffinity features a scheduler plugin that filters out any cluster that has been already scheduled/bounded
+// to the resource placement and prefers the same cluster which has an obsolete binding.
+package sameplacementaffinity
+
+import "go.goms.io/fleet/pkg/scheduler/framework"
+
+// Plugin is the scheduler plugin that enforces the same placement affinity and anti-affinity.
+// "Affinity" means a scheduler prefers the cluster which has an obsolete binding of the same placement in order to
+// minimize interruption between different scheduling runs.
+// "Anti-Affinity" means a scheduler filters out the cluster which has been already scheduled/bounded as two placements
+// cannot be scheduled on a cluster.
+type Plugin struct {
+	// The name of the plugin.
+	name string
+
+	// The framework handle.
+	handle framework.Handle
+}
+
+var (
+	// Verify that Plugin can connect to relevant extension points at compile time.
+	//
+	// This plugin leverages the following the extension points:
+	// * Filter
+	// * Score
+	//
+	// Note that successful connection to any of the extension points implies that the
+	// plugin already implements the Plugin interface.
+	_ framework.FilterPlugin = &Plugin{}
+	// TODO
+	// _ framework.ScorePlugin     = &Plugin{}
+)
+
+type samePlacementAntiAffinityPluginOptions struct {
+	// The name of the plugin.
+	name string
+}
+
+type Option func(*samePlacementAntiAffinityPluginOptions)
+
+var defaultPluginOptions = samePlacementAntiAffinityPluginOptions{
+	name: "SamePlacementAntiAffinity",
+}
+
+// WithName sets the name of the plugin.
+func WithName(name string) Option {
+	return func(o *samePlacementAntiAffinityPluginOptions) {
+		o.name = name
+	}
+}
+
+// New returns a new Plugin.
+func New(opts ...Option) Plugin {
+	options := defaultPluginOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	return Plugin{
+		name: options.name,
+	}
+}
+
+// Name returns the name of the plugin.
+func (p *Plugin) Name() string {
+	return p.name
+}
+
+// SetUpWithFramework sets up this plugin with a scheduler framework.
+func (p *Plugin) SetUpWithFramework(handle framework.Handle) {
+	p.handle = handle
+}