feat: example capped resources handler

Author: fra98

README.md

@@ -49,12 +49,7 @@ Additional flags:
 
 ### Example Implementation
 
-The repository includes an example handler implementation in `example/resourceslice/handler.go` that:
-
-- Generates CPU resources between 1 and 10 cores
-- Generates Memory resources between 1 and 5 GB
-- Allocates 110 pods
-- Uses a deterministic hash of the ResourceSlice name for consistent resource allocation
+The repository includes an example handler implementation in `examples/cappedresources/handler.go`, that accepts every resource request but caps the amount of resources the resource slice can use if they exceed the configured thresholds.
 
 ## Creating Custom Handlers
 

example/resourceslice/handler.go

@@ -0,0 +1,3 @@
+// Package cappedresources contains an handler that accepts every resource request but caps
+// the amount of resources the resource slice can use if they exceed the configured thresholds.
+package cappedresources

examples/cappedresources/doc.go

@@ -0,0 +1,58 @@
+package cappedresources
+
+import (
+	"context"
+
+	authv1beta1 "github.com/liqotech/liqo/apis/authentication/v1beta1"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/klog/v2"
+	ctrl "sigs.k8s.io/controller-runtime"
+
+	rshandler "github.com/liqotech/resource-slice-class-controller-template/pkg/resourceslice/handler"
+)
+
+// Handler implements the Handler interface for ResourceSlice.
+type Handler struct {
+	capResources corev1.ResourceList
+}
+
+// NewHandler creates a new capped resources handler.
+func NewHandler(maxResources corev1.ResourceList) rshandler.Handler {
+	return &Handler{
+		capResources: maxResources,
+	}
+}
+
+// Handle processes the ResourceSlice.
+func (h *Handler) Handle(_ context.Context, resourceSlice *authv1beta1.ResourceSlice) (ctrl.Result, error) {
+	// Generate and update resources in status
+	resources := h.getCappedResources(resourceSlice.Spec.Resources)
+
+	resourceSlice.Status.Resources = resources
+
+	klog.InfoS("Updated ResourceSlice status",
+		"name", resourceSlice.Name,
+		"namespace", resourceSlice.Namespace,
+		"cpu", resources.Cpu().String(),
+		"memory", resources.Memory().String(),
+		"pods", resources.Pods().String())
+
+	return ctrl.Result{}, nil
+}
+
+// getCappedResources sets the requested resources, but caps the amount of resources
+// to the maximum resources defined in the handler.
+func (h *Handler) getCappedResources(reqResources corev1.ResourceList) corev1.ResourceList {
+	cappedResources := corev1.ResourceList{}
+
+	for name, reqQuantity := range reqResources {
+		capQuantity, ok := h.capResources[name]
+		if ok && reqQuantity.Cmp(capQuantity) > 0 {
+			cappedResources[name] = capQuantity
+		} else {
+			cappedResources[name] = reqQuantity
+		}
+	}
+
+	return cappedResources
+}

examples/cappedresources/handler.go

@@ -1,11 +1,13 @@
-// Package main contains an an example main to setup and run a controller handling a ResourceSlice class
+// Package main contains an an example main to setup and run a controller handling a ResourceSlice class.
 package main
 
 import (
 	"flag"
 	"os"
 
 	authv1beta1 "github.com/liqotech/liqo/apis/authentication/v1beta1"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/resource"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
@@ -14,7 +16,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 
-	examplehandler "github.com/liqotech/resource-slice-class-controller-template/example/resourceslice"
+	cappedresources "github.com/liqotech/resource-slice-class-controller-template/examples/cappedresources"
 	"github.com/liqotech/resource-slice-class-controller-template/pkg/controller"
 )
 
@@ -66,7 +68,18 @@ func main() {
 	}
 
 	// Create the handler
-	rsHandler := examplehandler.NewHandler()
+	cappedQuantities := map[corev1.ResourceName]string{
+		corev1.ResourceCPU:              "4",
+		corev1.ResourceMemory:           "8Gi",
+		corev1.ResourcePods:             "110",
+		corev1.ResourceEphemeralStorage: "20Gi",
+	}
+	parsedQuantities, err := parseQuantities(cappedQuantities)
+	if err != nil {
+		klog.Errorf("unable to parse quantities: %v", err)
+		os.Exit(1)
+	}
+	rsHandler := cappedresources.NewHandler(parsedQuantities)
 
 	if err = controller.NewResourceSliceReconciler(
 		mgr.GetClient(),
@@ -94,3 +107,15 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func parseQuantities(quantities map[corev1.ResourceName]string) (corev1.ResourceList, error) {
+	resources := corev1.ResourceList{}
+	for name, quantity := range quantities {
+		qnt, err := resource.ParseQuantity(quantity)
+		if err != nil {
+			return nil, err
+		}
+		resources[name] = qnt
+	}
+	return resources, nil
+}

main.go

@@ -4,13 +4,17 @@ package controller
 import (
 	"context"
 	"fmt"
+	"strconv"
 
 	authv1beta1 "github.com/liqotech/liqo/apis/authentication/v1beta1"
+	"github.com/liqotech/liqo/pkg/consts"
 	"github.com/liqotech/liqo/pkg/liqo-controller-manager/authentication"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/client-go/tools/record"
 	"k8s.io/klog/v2"
 	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/builder"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/predicate"
 
@@ -40,8 +44,16 @@ func NewResourceSliceReconciler(cl client.Client, scheme *runtime.Scheme, record
 
 // SetupWithManager sets up the controller with the Manager.
 func (r *ResourceSliceReconciler) SetupWithManager(mgr ctrl.Manager) error {
+	// generate the predicate to filter just the ResourceSlices that are replicated
+	// (i.e., the ones for which we have the role of provider)
+	replicatedResSliceFilter, err := predicate.LabelSelectorPredicate(replicatedResourcesLabelSelector())
+	if err != nil {
+		klog.Error(err)
+		return err
+	}
+
 	return ctrl.NewControllerManagedBy(mgr).
-		For(&authv1beta1.ResourceSlice{}).
+		For(&authv1beta1.ResourceSlice{}, builder.WithPredicates(replicatedResSliceFilter)).
 		WithEventFilter(predicate.NewPredicateFuncs(func(obj client.Object) bool {
 			resourceSlice, ok := obj.(*authv1beta1.ResourceSlice)
 			if !ok {
@@ -101,3 +113,20 @@ func (r *ResourceSliceReconciler) Reconcile(ctx context.Context, req ctrl.Reques
 	// Return the reconciliation result
 	return res, nil
 }
+
+// replicatedResourcesLabelSelector is an helper function which returns a label selector to list all the replicated resources.
+func replicatedResourcesLabelSelector() metav1.LabelSelector {
+	return metav1.LabelSelector{
+		MatchExpressions: []metav1.LabelSelectorRequirement{
+			{
+				Key:      consts.ReplicationOriginLabel,
+				Operator: metav1.LabelSelectorOpExists,
+			},
+			{
+				Key:      consts.ReplicationStatusLabel,
+				Operator: metav1.LabelSelectorOpIn,
+				Values:   []string{strconv.FormatBool(true)},
+			},
+		},
+	}
+}