[node-labeler] Introduce workspace count controller

components/node-labeler/BUILD.yaml

@@ -5,11 +5,16 @@ packages:
       - "**/*.go"
       - "go.mod"
       - "go.sum"
+      - "crd/*.yaml"
     deps:
       - components/common-go:lib
+      - components/ws-manager-api/go:lib
+      - components/ws-manager-mk2:crd
     env:
       - CGO_ENABLED=0
       - GOOS=linux
+    prep:
+      - ["mv", "_deps/components-ws-manager-mk2--crd/workspace.gitpod.io_workspaces.yaml", "crd/workspace.gitpod.io_workspaces.yaml"]
     config:
       packaging: app
       buildCommand: ["go", "build", "-trimpath", "-ldflags", "-buildid= -w -s -X 'github.com/gitpod-io/gitpod/node-labeler/cmd.Version=commit-${__git_commit}'"]
@@ -36,3 +41,4 @@ packages:
       - "go.sum"
     deps:
       - components/common-go:lib
+      - components/ws-manager-api/go:lib

components/node-labeler/cmd/root.go

@@ -32,7 +32,7 @@ var (
 // rootCmd represents the base command when called without any subcommands
 var rootCmd = &cobra.Command{
 	Use:   ServiceName,
-	Short: "node-labeler is in charge of maintining the node labels that workspaces require to run in a node",
+	Short: "node-labeler is in charge of maintaining the node labels that workspaces require to run in a node",
 	PersistentPreRun: func(cmd *cobra.Command, args []string) {
 		log.Init(ServiceName, Version, jsonLog, verbose)
 	},

components/node-labeler/cmd/run.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/bombsimon/logrusr/v2"
+	workspacev1 "github.com/gitpod-io/gitpod/ws-manager/api/crd/v1"
 	"github.com/spf13/cobra"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
@@ -31,6 +32,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/cache"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/controller"
+	"sigs.k8s.io/controller-runtime/pkg/event"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/metrics"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
@@ -78,16 +80,16 @@ var runCmd = &cobra.Command{
 			LeaderElectionID: "node-labeler.gitpod.io",
 		})
 		if err != nil {
-			log.WithError(err).Fatal("unable to start node-labeber")
+			log.WithError(err).Fatal("unable to start node-labeler")
 		}
 
-		client, err := client.New(ctrl.GetConfigOrDie(), client.Options{})
+		kClient, err := client.New(ctrl.GetConfigOrDie(), client.Options{})
 		if err != nil {
 			log.WithError(err).Fatal("unable to create client")
 		}
 
 		r := &PodReconciler{
-			client,
+			kClient,
 		}
 
 		componentPredicate, err := predicate.LabelSelectorPredicate(metav1.LabelSelector{
@@ -110,6 +112,15 @@ var runCmd = &cobra.Command{
 			log.WithError(err).Fatal("unable to bind controller watch event handler")
 		}
 
+		wc, err := NewWorkspaceCountController(mgr.GetClient())
+		if err != nil {
+			log.WithError(err).Fatal("unable to create workspace count controller")
+		}
+		err = wc.SetupWithManager(mgr)
+		if err != nil {
+			log.WithError(err).Fatal("unable to bind workspace count controller")
+		}
+
 		metrics.Registry.MustRegister(NodeLabelerCounterVec)
 		metrics.Registry.MustRegister(NodeLabelerTimeHistVec)
 
@@ -123,10 +134,10 @@ var runCmd = &cobra.Command{
 			log.WithError(err).Fatal("unable to set up ready check")
 		}
 
-		log.Info("starting node-labeber")
+		log.Info("starting node-labeler")
 		err = mgr.Start(ctrl.SetupSignalHandler())
 		if err != nil {
-			log.WithError(err).Fatal("problem running node-labeber")
+			log.WithError(err).Fatal("problem running node-labeler")
 		}
 
 		log.Info("Received SIGINT - shutting down")
@@ -135,6 +146,8 @@ var runCmd = &cobra.Command{
 
 func init() {
 	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
+	utilruntime.Must(workspacev1.AddToScheme(scheme))
+
 	rootCmd.AddCommand(runCmd)
 }
 
@@ -249,6 +262,150 @@ func (r *PodReconciler) Reconcile(ctx context.Context, req reconcile.Request) (r
 	return reconcile.Result{}, nil
 }
 
+type WorkspaceCountController struct {
+	client.Client
+}
+
+func NewWorkspaceCountController(client client.Client) (*WorkspaceCountController, error) {
+	return &WorkspaceCountController{
+		Client: client,
+	}, nil
+}
+
+func (wc *WorkspaceCountController) SetupWithManager(mgr ctrl.Manager) error {
+	return ctrl.NewControllerManagedBy(mgr).
+		Named("workspace-count").
+		For(&workspacev1.Workspace{}).
+		WithEventFilter(workspaceFilter()).
+		Complete(wc)
+}
+
+func workspaceFilter() predicate.Predicate {
+	return predicate.Funcs{
+		CreateFunc: func(e event.CreateEvent) bool {
+			ws := e.Object.(*workspacev1.Workspace)
+			if ws.Status.Runtime == nil {
+				log.WithField("workspace", ws.Name).Info("workspace not ready yet")
+				return false
+			}
+
+			return ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != ""
+		},
+		UpdateFunc: func(e event.UpdateEvent) bool {
+			wsOld := e.ObjectOld.(*workspacev1.Workspace)
+			ws := e.ObjectNew.(*workspacev1.Workspace)
+			if wsOld.Status.Runtime == nil && ws.Status.Runtime != nil {
+				return true
+			}
+
+			// if we've seen runtime info before, there's no need to reconcile again
+			return false
+		},
+		DeleteFunc: func(e event.DeleteEvent) bool {
+			ws := e.Object.(*workspacev1.Workspace)
+			return ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != ""
+		},
+	}
+}
+
+func (wc *WorkspaceCountController) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+	log.WithField("request", req.NamespacedName.String()).Info("WorkspaceCountController reconciling")
+
+	var ws workspacev1.Workspace
+	if err := wc.Get(ctx, req.NamespacedName, &ws); err != nil {
+		if !errors.IsNotFound(err) {
+			log.WithError(err).WithField("workspace", req.NamespacedName).Error("unable to fetch Workspace")
+			return ctrl.Result{}, err
+		}
+		// If workspace not found, do a full reconciliation
+		log.WithField("workspace", req.NamespacedName).Info("Workspace not found, reconciling all nodes")
+		return wc.reconcileAllNodes(ctx)
+	}
+
+	if ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != "" {
+		var workspaceList workspacev1.WorkspaceList
+		if err := wc.List(ctx, &workspaceList); err != nil {
+			log.WithError(err).Error("failed to list workspaces")
+			return ctrl.Result{}, err
+		}
+
+		count := 0
+		nodeName := ws.Status.Runtime.NodeName
+		for _, ws := range workspaceList.Items {
+			if ws.Status.Runtime != nil &&
+				ws.Status.Runtime.NodeName == nodeName &&
+				ws.DeletionTimestamp.IsZero() {
+				count++
+			}
+		}
+
+		if err := wc.updateNodeAnnotation(ctx, nodeName, count); err != nil {
+			return ctrl.Result{}, err
+		}
+		log.WithField("node", nodeName).WithField("count", count).Info("updated node annotation")
+	}
+
+	return ctrl.Result{}, nil
+}
+
+func (wc *WorkspaceCountController) reconcileAllNodes(ctx context.Context) (ctrl.Result, error) {
+	var workspaceList workspacev1.WorkspaceList
+	if err := wc.List(ctx, &workspaceList); err != nil {
+		log.WithError(err).Error("failed to list workspaces")
+		return ctrl.Result{}, err
+	}
+
+	workspaceCounts := make(map[string]int)
+	for _, ws := range workspaceList.Items {
+		if ws.Status.Runtime != nil &&
+			ws.Status.Runtime.NodeName != "" &&
+			ws.DeletionTimestamp.IsZero() {
+			workspaceCounts[ws.Status.Runtime.NodeName]++
+		}
+	}
+
+	var nodes corev1.NodeList
+	if err := wc.List(ctx, &nodes); err != nil {
+		log.WithError(err).Error("failed to list nodes")
+		return ctrl.Result{}, err
+	}
+
+	for _, node := range nodes.Items {
+		count := workspaceCounts[node.Name]
+		if err := wc.updateNodeAnnotation(ctx, node.Name, count); err != nil {
+			log.WithError(err).WithField("node", node.Name).Error("failed to update node")
+			continue
+		}
+		log.WithField("node", node.Name).WithField("count", count).Info("updated node annotation")
+	}
+
+	return ctrl.Result{}, nil
+}
+
+func (wc *WorkspaceCountController) updateNodeAnnotation(ctx context.Context, nodeName string, count int) error {
+	return retry.RetryOnConflict(retry.DefaultBackoff, func() error {
+		var node corev1.Node
+		err := wc.Get(ctx, types.NamespacedName{Name: nodeName}, &node)
+		if err != nil {
+			return fmt.Errorf("obtaining node %s: %w", nodeName, err)
+		}
+
+		if node.Annotations == nil {
+			node.Annotations = make(map[string]string)
+		}
+
+		if count > 0 {
+			node.Annotations["cluster-autoscaler.kubernetes.io/scale-down-disabled"] = "true"
+			log.WithField("nodeName", nodeName).Info("disabling scale-down for node")
+		} else {
+			delete(node.Annotations, "cluster-autoscaler.kubernetes.io/scale-down-disabled")
+			log.WithField("nodeName", nodeName).Info("enabling scale-down for node")
+		}
+
+		return wc.Update(ctx, &node)
+	})
+}
+
 func updateLabel(label string, add bool, nodeName string, client client.Client) error {
 	return retry.RetryOnConflict(retry.DefaultBackoff, func() error {
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)