Support manage single node

.github/workflows/test.yaml

@@ -75,6 +75,7 @@ jobs:
         case:
           - kwok
           - kwok-with-cni
+          - kwok-single-node
     continue-on-error: false
     runs-on: ubuntu-latest
     steps:

kustomize/kwok/deployment.yaml

@@ -14,6 +14,7 @@ spec:
             - --manage-all-nodes=false
             - --manage-nodes-with-annotation-selector=kwok.x-k8s.io/node=fake
             - --manage-nodes-with-label-selector=
+            - --manage-single-node=
             - --disregard-status-with-annotation-selector=kwok.x-k8s.io/status=custom
             - --disregard-status-with-label-selector=
             - --node-ip=$(POD_IP)

pkg/apis/config/v1alpha1/kwok_configuration_types.go

@@ -70,19 +70,33 @@ type KwokConfigurationOptions struct {
 	// is the default value for flag --tls-private-key-file
 	TLSPrivateKeyFile string `json:"tlsPrivateKeyFile,omitempty"`
 
+	// ManageSingleNode is the option to manage a single node name.
+	// is the default value for flag --manage-single-node
+	// Note: when `manage-all-nodes` is specified as true or
+	// `manage-nodes-with-label-selector` or `manage-nodes-with-annotation-selector` is specified,
+	// this is a no-op.
+	ManageSingleNode string `json:"manageSingleNode,omitempty"`
+
 	// Default option to manage (i.e., maintain heartbeat/liveness of) all Nodes or not.
 	// is the default value for flag --manage-all-nodes
+	// Note: when `manage-single-node` is specified as true or
+	// `manage-nodes-with-label-selector` or `manage-nodes-with-annotation-selector` is specified,
+	// this is a no-op.
 	// +default=false
 	ManageAllNodes *bool `json:"manageAllNodes,omitempty"`
 
 	// Default annotations specified on Nodes to demand manage.
-	// Note: when `all-node-manage` is specified as true, this is a no-op.
 	// is the default value for flag --manage-nodes-with-annotation-selector
+	// Note: when `all-node-manage` is specified as true or
+	// `manage-single-node` is specified,
+	// this is a no-op.
 	ManageNodesWithAnnotationSelector string `json:"manageNodesWithAnnotationSelector,omitempty"`
 
 	// Default labels specified on Nodes to demand manage.
-	// Note: when `all-node-manage` is specified as true, this is a no-op.
 	// is the default value for flag --manage-nodes-with-label-selector
+	// Note: when `all-node-manage` is specified as true or
+	// `manage-single-node` is specified,
+	// this is a no-op.
 	ManageNodesWithLabelSelector string `json:"manageNodesWithLabelSelector,omitempty"`
 
 	// If a Node/Pod is on a managed Node and has this annotation status will not be modified

pkg/apis/internalversion/kwok_configuration_types.go

@@ -53,6 +53,9 @@ type KwokConfigurationOptions struct {
 	// TLSPrivateKeyFile is the ile containing x509 private key
 	TLSPrivateKeyFile string
 
+	// ManageSingleNode is the option to manage a single node name
+	ManageSingleNode string
+
 	// Default option to manage (i.e., maintain heartbeat/liveness of) all Nodes or not.
 	ManageAllNodes bool
 
@@ -74,11 +77,11 @@ type KwokConfigurationOptions struct {
 	// Experimental support for getting pod ip from CNI, for CNI-related components, Only works with Linux.
 	EnableCNI bool
 
-	// enableDebuggingHandlers enables server endpoints for log collection
+	// EnableDebuggingHandlers enables server endpoints for log collection
 	// and local running of containers and commands
 	EnableDebuggingHandlers bool
 
-	// enableContentionProfiling enables lock contention profiling, if enableDebuggingHandlers is true.
+	// EnableContentionProfiling enables lock contention profiling, if enableDebuggingHandlers is true.
 	EnableContentionProfiling bool
 
 	// EnableProfiling enables /debug/pprof handler.

pkg/kwok/cmd/root.go

@@ -79,9 +79,10 @@ func NewCommand(ctx context.Context) *cobra.Command {
 	cmd.Flags().IntVar(&flags.Options.NodePort, "node-port", flags.Options.NodePort, "Port of the node")
 	cmd.Flags().StringVar(&flags.Options.TLSCertFile, "tls-cert-file", flags.Options.TLSCertFile, "File containing the default x509 Certificate for HTTPS")
 	cmd.Flags().StringVar(&flags.Options.TLSPrivateKeyFile, "tls-private-key-file", flags.Options.TLSPrivateKeyFile, "File containing the default x509 private key matching --tls-cert-file")
-	cmd.Flags().BoolVar(&flags.Options.ManageAllNodes, "manage-all-nodes", flags.Options.ManageAllNodes, "All nodes will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector and manage-nodes-with-label-selector.")
-	cmd.Flags().StringVar(&flags.Options.ManageNodesWithAnnotationSelector, "manage-nodes-with-annotation-selector", flags.Options.ManageNodesWithAnnotationSelector, "Nodes that match the annotation selector will be watched and managed. It's conflicted with manage-all-nodes.")
-	cmd.Flags().StringVar(&flags.Options.ManageNodesWithLabelSelector, "manage-nodes-with-label-selector", flags.Options.ManageNodesWithLabelSelector, "Nodes that match the label selector will be watched and managed. It's conflicted with manage-all-nodes.")
+	cmd.Flags().StringVar(&flags.Options.ManageSingleNode, "manage-single-node", flags.Options.ManageSingleNode, "Node that matches the name will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector, manage-nodes-with-label-selector and manage-all-nodes.")
+	cmd.Flags().BoolVar(&flags.Options.ManageAllNodes, "manage-all-nodes", flags.Options.ManageAllNodes, "All nodes will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector, manage-nodes-with-label-selector and manage-single-node.")
+	cmd.Flags().StringVar(&flags.Options.ManageNodesWithAnnotationSelector, "manage-nodes-with-annotation-selector", flags.Options.ManageNodesWithAnnotationSelector, "Nodes that match the annotation selector will be watched and managed. It's conflicted with manage-all-nodes and manage-single-node.")
+	cmd.Flags().StringVar(&flags.Options.ManageNodesWithLabelSelector, "manage-nodes-with-label-selector", flags.Options.ManageNodesWithLabelSelector, "Nodes that match the label selector will be watched and managed. It's conflicted with manage-all-nodes and manage-single-node.")
 	cmd.Flags().StringVar(&flags.Options.DisregardStatusWithAnnotationSelector, "disregard-status-with-annotation-selector", flags.Options.DisregardStatusWithAnnotationSelector, "All node/pod status excluding the ones that match the annotation selector will be watched and managed.")
 	cmd.Flags().StringVar(&flags.Options.DisregardStatusWithLabelSelector, "disregard-status-with-label-selector", flags.Options.DisregardStatusWithLabelSelector, "All node/pod status excluding the ones that match the label selector will be watched and managed.")
 	cmd.Flags().StringVar(&flags.Kubeconfig, "kubeconfig", flags.Kubeconfig, "Path to the kubeconfig file to use")
@@ -229,24 +230,20 @@ func runE(ctx context.Context, flags *flagpole) error {
 		return err
 	}
 
-	if flags.Options.ManageAllNodes {
-		if flags.Options.ManageNodesWithAnnotationSelector != "" || flags.Options.ManageNodesWithLabelSelector != "" {
-			logger.Error("manage-all-nodes is conflicted with manage-nodes-with-annotation-selector and manage-nodes-with-label-selector.", nil)
-			os.Exit(1)
-		}
+	switch {
+	case flags.Options.ManageSingleNode != "":
+		logger.Info("Watch single node",
+			"node", flags.Options.ManageSingleNode,
+		)
+	case flags.Options.ManageAllNodes:
 		logger.Info("Watch all nodes")
-	} else if flags.Options.ManageNodesWithAnnotationSelector != "" || flags.Options.ManageNodesWithLabelSelector != "" {
+	case flags.Options.ManageNodesWithAnnotationSelector != "" || flags.Options.ManageNodesWithLabelSelector != "":
 		logger.Info("Watch nodes",
 			"annotation", flags.Options.ManageNodesWithAnnotationSelector,
 			"label", flags.Options.ManageNodesWithLabelSelector,
 		)
 	}
 
-	err = waitForReady(ctx, typedClient)
-	if err != nil {
-		return err
-	}
-
 	id, err := controllers.Identity()
 	if err != nil {
 		return err
@@ -261,6 +258,7 @@ func runE(ctx context.Context, flags *flagpole) error {
 		EnableCNI:                             flags.Options.EnableCNI,
 		EnableMetrics:                         enableMetrics,
 		EnablePodCache:                        enableMetrics,
+		ManageSingleNode:                      flags.Options.ManageSingleNode,
 		ManageAllNodes:                        flags.Options.ManageAllNodes,
 		ManageNodesWithAnnotationSelector:     flags.Options.ManageNodesWithAnnotationSelector,
 		ManageNodesWithLabelSelector:          flags.Options.ManageNodesWithLabelSelector,
@@ -282,6 +280,11 @@ func runE(ctx context.Context, flags *flagpole) error {
 		return err
 	}
 
+	err = waitForReady(ctx, typedClient)
+	if err != nil {
+		return err
+	}
+
 	serverAddress := flags.Options.ServerAddress
 	if serverAddress == "" && flags.Options.NodePort != 0 {
 		serverAddress = "0.0.0.0:" + format.String(flags.Options.NodePort)

pkg/kwok/controllers/controller.go

@@ -112,6 +112,7 @@ type Config struct {
 	EnableCNI                             bool
 	TypedClient                           kubernetes.Interface
 	TypedKwokClient                       versioned.Interface
+	ManageSingleNode                      string
 	ManageAllNodes                        bool
 	ManageNodesWithAnnotationSelector     string
 	ManageNodesWithLabelSelector          string
@@ -132,16 +133,31 @@ type Config struct {
 	EnablePodCache                        bool
 }
 
-// NewController creates a new fake kubelet controller
-func NewController(conf Config) (*Controller, error) {
+func (c Config) validate() error {
 	switch {
-	case conf.ManageAllNodes:
-		conf.ManageNodesWithAnnotationSelector = ""
-		conf.ManageNodesWithLabelSelector = ""
-	case conf.ManageNodesWithAnnotationSelector != "":
-	case conf.ManageNodesWithLabelSelector != "":
+	case c.ManageSingleNode != "":
+		if c.ManageAllNodes {
+			return fmt.Errorf("manage-single-node is conflicted with manage-all-nodes")
+		}
+		if c.ManageNodesWithAnnotationSelector != "" || c.ManageNodesWithLabelSelector != "" {
+			return fmt.Errorf("manage-single-node is conflicted with manage-nodes-with-annotation-selector or manage-nodes-with-label-selector")
+		}
+	case c.ManageAllNodes:
+		if c.ManageNodesWithAnnotationSelector != "" || c.ManageNodesWithLabelSelector != "" {
+			return fmt.Errorf("manage-all-nodes is conflicted with manage-nodes-with-annotation-selector or manage-nodes-with-label-selector")
+		}
+	case c.ManageNodesWithAnnotationSelector != "" || c.ManageNodesWithLabelSelector != "":
 	default:
-		return nil, fmt.Errorf("no nodes are managed")
+		return fmt.Errorf("no nodes are managed")
+	}
+	return nil
+}
+
+// NewController creates a new fake kubelet controller
+func NewController(conf Config) (*Controller, error) {
+	err := conf.validate()
+	if err != nil {
+		return nil, err
 	}
 
 	n := &Controller{
@@ -170,14 +186,34 @@ func (c *Controller) Start(ctx context.Context) error {
 		onLeaseNodeManageFunc func(nodeName string)
 		onNodeManagedFunc     func(nodeName string)
 		readOnlyFunc          func(nodeName string) bool
+
+		manageNodesWithLabelSelector      string
+		manageNodesWithAnnotationSelector string
+		manageNodesWithFieldSelector      string
+		manageNodeLeasesWithFieldSelector string
+		managePodsWithFieldSelector       string
 	)
 
+	switch {
+	case conf.ManageSingleNode != "":
+		managePodsWithFieldSelector = fields.OneTermEqualSelector("spec.nodeName", conf.ManageSingleNode).String()
+		manageNodesWithFieldSelector = fields.OneTermEqualSelector("metadata.name", conf.ManageSingleNode).String()
+		manageNodeLeasesWithFieldSelector = fields.OneTermEqualSelector("metadata.name", conf.ManageSingleNode).String()
+	case conf.ManageAllNodes:
+		managePodsWithFieldSelector = fields.OneTermNotEqualSelector("spec.nodeName", "").String()
+	case conf.ManageNodesWithLabelSelector != "" || conf.ManageNodesWithAnnotationSelector != "":
+		manageNodesWithLabelSelector = conf.ManageNodesWithLabelSelector
+		manageNodesWithAnnotationSelector = conf.ManageNodesWithAnnotationSelector
+		managePodsWithFieldSelector = fields.OneTermNotEqualSelector("spec.nodeName", "").String()
+	}
+
 	nodeChan := make(chan informer.Event[*corev1.Node], 1)
 	nodesCli := conf.TypedClient.CoreV1().Nodes()
 	nodesInformer := informer.NewInformer[*corev1.Node, *corev1.NodeList](nodesCli)
 	nodesCache, err := nodesInformer.WatchWithCache(ctx, informer.Option{
-		LabelSelector:      conf.ManageNodesWithLabelSelector,
-		AnnotationSelector: conf.ManageNodesWithAnnotationSelector,
+		LabelSelector:      manageNodesWithLabelSelector,
+		AnnotationSelector: manageNodesWithAnnotationSelector,
+		FieldSelector:      manageNodesWithFieldSelector,
 	}, nodeChan)
 	if err != nil {
 		return fmt.Errorf("failed to watch nodes: %w", err)
@@ -188,7 +224,7 @@ func (c *Controller) Start(ctx context.Context) error {
 	podsInformer := informer.NewInformer[*corev1.Pod, *corev1.PodList](podsCli)
 
 	podWatchOption := informer.Option{
-		FieldSelector: fields.OneTermNotEqualSelector("spec.nodeName", "").String(),
+		FieldSelector: managePodsWithFieldSelector,
 	}
 
 	var podsCache informer.Getter[*corev1.Pod]
@@ -205,7 +241,9 @@ func (c *Controller) Start(ctx context.Context) error {
 		nodeLeasesChan = make(chan informer.Event[*coordinationv1.Lease], 1)
 		nodeLeasesCli := conf.TypedClient.CoordinationV1().Leases(corev1.NamespaceNodeLease)
 		nodeLeasesInformer := informer.NewInformer[*coordinationv1.Lease, *coordinationv1.LeaseList](nodeLeasesCli)
-		err = nodeLeasesInformer.Watch(ctx, informer.Option{}, nodeLeasesChan)
+		err = nodeLeasesInformer.Watch(ctx, informer.Option{
+			FieldSelector: manageNodeLeasesWithFieldSelector,
+		}, nodeLeasesChan)
 		if err != nil {
 			return fmt.Errorf("failed to watch nodes: %w", err)
 		}

site/content/en/docs/generated/apis.md

@@ -1860,14 +1860,32 @@ is the default value for flag &ndash;tls-private-key-file</p>
 </tr>
 <tr>
 <td>
+<code>manageSingleNode</code>
+<em>
+string
+</em>
+</td>
+<td>
+<p>ManageSingleNode is the option to manage a single node name.
+is the default value for flag &ndash;manage-single-node
+Note: when <code>manage-all-nodes</code> is specified as true or
+<code>manage-nodes-with-label-selector</code> or <code>manage-nodes-with-annotation-selector</code> is specified,
+this is a no-op.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>manageAllNodes</code>
 <em>
 bool
 </em>
 </td>
 <td>
 <p>Default option to manage (i.e., maintain heartbeat/liveness of) all Nodes or not.
-is the default value for flag &ndash;manage-all-nodes</p>
+is the default value for flag &ndash;manage-all-nodes
+Note: when <code>manage-single-node</code> is specified as true or
+<code>manage-nodes-with-label-selector</code> or <code>manage-nodes-with-annotation-selector</code> is specified,
+this is a no-op.</p>
 </td>
 </tr>
 <tr>
@@ -1879,8 +1897,10 @@ string
 </td>
 <td>
 <p>Default annotations specified on Nodes to demand manage.
-Note: when <code>all-node-manage</code> is specified as true, this is a no-op.
-is the default value for flag &ndash;manage-nodes-with-annotation-selector</p>
+is the default value for flag &ndash;manage-nodes-with-annotation-selector
+Note: when <code>all-node-manage</code> is specified as true or
+<code>manage-single-node</code> is specified,
+this is a no-op.</p>
 </td>
 </tr>
 <tr>
@@ -1892,8 +1912,10 @@ string
 </td>
 <td>
 <p>Default labels specified on Nodes to demand manage.
-Note: when <code>all-node-manage</code> is specified as true, this is a no-op.
-is the default value for flag &ndash;manage-nodes-with-label-selector</p>
+is the default value for flag &ndash;manage-nodes-with-label-selector
+Note: when <code>all-node-manage</code> is specified as true or
+<code>manage-single-node</code> is specified,
+this is a no-op.</p>
 </td>
 </tr>
 <tr>

site/content/en/docs/generated/kwok.md

@@ -17,9 +17,10 @@ kwok [flags]
       --experimental-enable-cni                            Experimental support for getting pod ip from CNI, for CNI-related components, Only works with Linux
   -h, --help                                               help for kwok
       --kubeconfig string                                  Path to the kubeconfig file to use (default "~/.kube/config")
-      --manage-all-nodes                                   All nodes will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector and manage-nodes-with-label-selector.
-      --manage-nodes-with-annotation-selector string       Nodes that match the annotation selector will be watched and managed. It's conflicted with manage-all-nodes.
-      --manage-nodes-with-label-selector string            Nodes that match the label selector will be watched and managed. It's conflicted with manage-all-nodes.
+      --manage-all-nodes                                   All nodes will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector, manage-nodes-with-label-selector and manage-single-node.
+      --manage-nodes-with-annotation-selector string       Nodes that match the annotation selector will be watched and managed. It's conflicted with manage-all-nodes and manage-single-node.
+      --manage-nodes-with-label-selector string            Nodes that match the label selector will be watched and managed. It's conflicted with manage-all-nodes and manage-single-node.
+      --manage-single-node string                          Node that matches the name will be watched and managed. It's conflicted with manage-nodes-with-annotation-selector, manage-nodes-with-label-selector and manage-all-nodes.
       --master string                                      The address of the Kubernetes API server (overrides any value in kubeconfig).
       --node-ip string                                     IP of the node
       --node-lease-duration-seconds uint                   Duration of node lease seconds

test/kwok-single-node/fake-deployment.yaml

@@ -0,0 +1,32 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: fake-pod
+  namespace: default
+spec:
+  replicas: 5
+  selector:
+    matchLabels:
+      app: fake-pod
+  template:
+    metadata:
+      labels:
+        app: fake-pod
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+              - matchExpressions:
+                  - key: type
+                    operator: In
+                    values:
+                      - kwok-controller
+      tolerations:
+        - key: "kwok-controller/provider"
+          operator: "Exists"
+          effect: "NoSchedule"
+      containers:
+        - name: fake-container
+          image: fake
+      nodeName: fake-node

test/kwok-single-node/fake-node.yaml

@@ -0,0 +1,21 @@
+apiVersion: v1
+kind: Node
+metadata:
+  annotations:
+    kwok.x-k8s.io/node: fake
+    node.alpha.kubernetes.io/ttl: "0"
+  labels:
+    beta.kubernetes.io/arch: amd64
+    beta.kubernetes.io/os: linux
+    kubernetes.io/arch: amd64
+    kubernetes.io/hostname: fake-node
+    kubernetes.io/os: linux
+    kubernetes.io/role: agent
+    node-role.kubernetes.io/agent: ""
+    type: kwok-controller
+  name: fake-node
+spec:
+  taints:
+    - effect: NoSchedule
+      key: kwok-controller/provider
+      value: fake