[node-labeler] Introduce workspace count controller (#20509)

* [ws-daemon] Introduce pod count controller

* remove unnecessary variable

* move to `node-labeler`

* act on ws crds

* Fix runtime not filled in yet

* Make tests pass!

* Improve test file structure

* Fix `node-labeler:lib` build

* Remove unnecessary changes

* Address some review comments (thanks, kyle!)

* Try caching?

* Queue deleted nodes and periodically reconcile it all

* WCC cleanup function

* Fix tests

* Update name

* Add metrics for controller

* Add synchronization for node reconciliation to prevent race conditions

* Address review comments

* Remove superflous log

* Remove unneeded metrics and add cool log line

* big yellow warning for a thing that should not happen

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}'"]
@@ -34,5 +39,10 @@ packages:
       - "**/*.go"
       - "go.mod"
       - "go.sum"
+      - "crd/*.yaml"
     deps:
       - components/common-go:lib
+      - components/ws-manager-api/go:lib
+      - components/ws-manager-mk2:crd
+    prep:
+      - ["mv", "_deps/components-ws-manager-mk2--crd/workspace.gitpod.io_workspaces.yaml", "crd/workspace.gitpod.io_workspaces.yaml"]

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"
@@ -31,7 +32,9 @@ 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/manager"
 	"sigs.k8s.io/controller-runtime/pkg/metrics"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 	"sigs.k8s.io/controller-runtime/pkg/predicate"
@@ -78,16 +81,16 @@ 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 +113,36 @@ var runCmd = &cobra.Command{
 			log.WithError(err).Fatal("unable to bind controller watch event handler")
 		}
 
+		if err := mgr.GetFieldIndexer().IndexField(context.Background(), &workspacev1.Workspace{}, "status.runtime.nodeName", func(o client.Object) []string {
+			ws := o.(*workspacev1.Workspace)
+			if ws.Status.Runtime == nil {
+				return nil
+			}
+			return []string{ws.Status.Runtime.NodeName}
+		}); err != nil {
+			log.WithError(err).Fatal("unable to create workspace indexer")
+			return
+		}
+
+		nsac, err := NewNodeScaledownAnnotationController(mgr.GetClient())
+		if err != nil {
+			log.WithError(err).Fatal("unable to create node scaledown annotation controller")
+		}
+		err = nsac.SetupWithManager(mgr)
+		if err != nil {
+			log.WithError(err).Fatal("unable to bind node scaledown annotation controller")
+		}
+
+		err = mgr.Add(manager.RunnableFunc(func(ctx context.Context) error {
+			<-ctx.Done()
+			log.Info("Received shutdown signal - stopping NodeScaledownAnnotationController")
+			nsac.Stop()
+			return nil
+		}))
+		if err != nil {
+			log.WithError(err).Fatal("couldn't properly clean up node scaledown annotation controller")
+		}
+
 		metrics.Registry.MustRegister(NodeLabelerCounterVec)
 		metrics.Registry.MustRegister(NodeLabelerTimeHistVec)
 
@@ -123,10 +156,10 @@ 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 +168,8 @@ var runCmd = &cobra.Command{
 
 func init() {
 	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
+	utilruntime.Must(workspacev1.AddToScheme(scheme))
+
 	rootCmd.AddCommand(runCmd)
 }
 
@@ -249,6 +284,207 @@ func (r *PodReconciler) Reconcile(ctx context.Context, req reconcile.Request) (r
 	return reconcile.Result{}, nil
 }
 
+type NodeScaledownAnnotationController struct {
+	client.Client
+	nodesToReconcile chan string
+	stopChan         chan struct{}
+}
+
+func NewNodeScaledownAnnotationController(client client.Client) (*NodeScaledownAnnotationController, error) {
+	controller := &NodeScaledownAnnotationController{
+		Client:           client,
+		nodesToReconcile: make(chan string, 1000),
+		stopChan:         make(chan struct{}),
+	}
+
+	return controller, nil
+}
+
+func (c *NodeScaledownAnnotationController) SetupWithManager(mgr ctrl.Manager) error {
+	go c.reconciliationWorker()
+	go c.periodicReconciliation()
+
+	return ctrl.NewControllerManagedBy(mgr).
+		Named("node-scaledown-annotation-controller").
+		For(&workspacev1.Workspace{}).
+		WithEventFilter(c.workspaceFilter()).
+		Complete(c)
+}
+
+// periodicReconciliation periodically reconciles all nodes in the cluster
+func (c *NodeScaledownAnnotationController) periodicReconciliation() {
+	ticker := time.NewTicker(5 * time.Minute)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			log.Info("starting periodic full reconciliation")
+			ctx := context.Background()
+			if _, err := c.reconcileAllNodes(ctx); err != nil {
+				log.WithError(err).Error("periodic reconciliation failed")
+			}
+		case <-c.stopChan:
+			log.Info("stopping periodic full reconciliation")
+			return
+		}
+	}
+}
+
+// reconciliationWorker consumes nodesToReconcile and reconciles each node
+func (c *NodeScaledownAnnotationController) reconciliationWorker() {
+	log.Info("reconciliation worker started")
+	for {
+		select {
+		case nodeName := <-c.nodesToReconcile:
+			ctx := context.Background()
+			if err := c.reconcileNode(ctx, nodeName); err != nil {
+				log.WithError(err).WithField("node", nodeName).Error("failed to reconcile node from queue")
+			}
+		case <-c.stopChan:
+			log.Info("reconciliation worker stopping")
+			return
+		}
+	}
+}
+
+func (c *NodeScaledownAnnotationController) 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 we haven't seen runtime info before and now it's there, let's reconcile.
+			// similarly, if the node name changed, we need to reconcile the old node as well.
+			if (wsOld.Status.Runtime == nil && ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != "") || // we just got runtime info
+				(wsOld.Status.Runtime != nil && ws.Status.Runtime != nil && wsOld.Status.Runtime.NodeName != ws.Status.Runtime.NodeName) { // node name changed
+				if wsOld.Status.Runtime != nil && wsOld.Status.Runtime.NodeName != "" {
+					c.queueNodeForReconciliation(wsOld.Status.Runtime.NodeName)
+				}
+				return true
+			}
+
+			return false
+		},
+		DeleteFunc: func(e event.DeleteEvent) bool {
+			ws := e.Object.(*workspacev1.Workspace)
+			if ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != "" {
+				c.queueNodeForReconciliation(ws.Status.Runtime.NodeName)
+				return true
+			}
+			return false
+		},
+	}
+}
+
+func (c *NodeScaledownAnnotationController) queueNodeForReconciliation(nodeName string) {
+	select {
+	case c.nodesToReconcile <- nodeName:
+		log.WithField("node", nodeName).Info("queued node for reconciliation")
+	default:
+		log.WithField("node", nodeName).Warn("reconciliation queue full")
+	}
+}
+
+func (c *NodeScaledownAnnotationController) 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 := c.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
+		}
+		return ctrl.Result{}, nil
+	}
+
+	if ws.Status.Runtime != nil && ws.Status.Runtime.NodeName != "" {
+		c.queueNodeForReconciliation(ws.Status.Runtime.NodeName)
+	}
+
+	log.WithField("runtime", ws.Status.Runtime).Warn("reconciling object with no Runtime/NodeName, which wasn't filtered out by workspaceFilter")
+	return ctrl.Result{}, nil
+}
+
+// Cleanup method to be called when shutting down the controller
+func (wc *NodeScaledownAnnotationController) Stop() {
+	close(wc.stopChan)
+}
+
+func (c *NodeScaledownAnnotationController) reconcileAllNodes(ctx context.Context) (ctrl.Result, error) {
+	var nodes corev1.NodeList
+	if err := c.List(ctx, &nodes); err != nil {
+		log.WithError(err).Error("failed to list nodes")
+		return ctrl.Result{}, err
+	}
+
+	for _, node := range nodes.Items {
+		c.queueNodeForReconciliation(node.Name)
+	}
+
+	return ctrl.Result{}, nil
+}
+
+func (c *NodeScaledownAnnotationController) reconcileNode(ctx context.Context, nodeName string) error {
+	var workspaceList workspacev1.WorkspaceList
+	if err := c.List(ctx, &workspaceList, client.MatchingFields{
+		"status.runtime.nodeName": nodeName,
+	}); err != nil {
+		return fmt.Errorf("failed to list workspaces: %w", err)
+	}
+
+	log.WithField("node", nodeName).WithField("count", len(workspaceList.Items)).Info("acting on workspaces")
+	count := len(workspaceList.Items)
+
+	return c.updateNodeAnnotation(ctx, nodeName, count)
+}
+
+func (c *NodeScaledownAnnotationController) updateNodeAnnotation(ctx context.Context, nodeName string, count int) error {
+	return retry.RetryOnConflict(retry.DefaultBackoff, func() error {
+		ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+		defer cancel()
+
+		var node corev1.Node
+		err := c.Get(ctx, types.NamespacedName{Name: nodeName}, &node)
+		if err != nil {
+			return fmt.Errorf("obtaining node %s: %w", nodeName, err)
+		}
+
+		shouldDisableScaleDown := count > 0
+		currentlyDisabled := false
+		if val, exists := node.Annotations["cluster-autoscaler.kubernetes.io/scale-down-disabled"]; exists {
+			currentlyDisabled = val == "true"
+		}
+
+		// Only update if the state needs to change
+		if shouldDisableScaleDown != currentlyDisabled {
+			if node.Annotations == nil {
+				node.Annotations = make(map[string]string)
+			}
+
+			if shouldDisableScaleDown {
+				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 c.Update(ctx, &node)
+		}
+
+		return nil
+	})
+}
+
 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)