if control plane node, half the root disk and make an etcd disk with it,

add docs

controller/linodemachine_controller.go

@@ -317,30 +317,40 @@ func (r *LinodeMachineReconciler) reconcileCreate(
 		linodeInstance = &linodeInstances[0]
 	case 0:
 		// get the bootstrap data for the Linode instance and set it for create config
-		createConfig, err := r.newCreateConfig(ctx, machineScope, tags, logger)
+		createOpts, err := r.newCreateConfig(ctx, machineScope, tags, logger)
 		if err != nil {
 			logger.Error(err, "Failed to create Linode machine create config")
 
 			return nil, err
 		}
 
 		if machineScope.LinodeCluster.Spec.VPCRef != nil {
-			iface, err := r.getVPCInterfaceConfig(ctx, machineScope, createConfig.Interfaces, logger)
+			iface, err := r.getVPCInterfaceConfig(ctx, machineScope, createOpts.Interfaces, logger)
 			if err != nil {
 				logger.Error(err, "Failed to get VPC interface config")
 
 				return nil, err
 			}
 
-			createConfig.Interfaces = append(createConfig.Interfaces, *iface)
+			createOpts.Interfaces = append(createOpts.Interfaces, *iface)
 		}
 
-		linodeInstance, err = machineScope.LinodeClient.CreateInstance(ctx, *createConfig)
+		linodeInstance, err = machineScope.LinodeClient.CreateInstance(ctx, *createOpts)
 		if err != nil {
 			logger.Error(err, "Failed to create Linode machine instance")
 
 			return nil, err
 		}
+
+		// create etcd disk only if this is a control plane node
+		if kutil.IsControlPlaneMachine(machineScope.Machine) {
+			if err = r.configureDisks(ctx, logger, machineScope, linodeInstance.ID); err != nil {
+				logger.Error(err, "Failed to configure instance disks")
+
+				return nil, err
+			}
+		}
+
 	default:
 		err = errors.New("multiple instances")
 
@@ -378,6 +388,67 @@ func (r *LinodeMachineReconciler) reconcileCreate(
 	return linodeInstance, nil
 }
 
+func (r *LinodeMachineReconciler) configureDisks(
+	ctx context.Context,
+	logger logr.Logger,
+	machineScope *scope.MachineScope,
+	linodeInstanceID int,
+) error {
+	// get the default instance config
+	configs, err := machineScope.LinodeClient.ListInstanceConfigs(ctx, linodeInstanceID, &linodego.ListOptions{})
+	if err != nil || len(configs) == 0 {
+		logger.Error(err, "Failed to list instance configs")
+
+		return err
+	}
+	instanceConfig := configs[0]
+
+	// carve out half the root disk space to be used for the etcd disk
+	rootDiskID := instanceConfig.Devices.SDA.DiskID
+	rootDisk, err := machineScope.LinodeClient.GetInstanceDisk(ctx, linodeInstanceID, rootDiskID)
+	if err != nil {
+		logger.Error(err, "Failed to get root disk for instance")
+
+		return err
+	}
+	//nolint:gomnd // cutting disk in half
+	diskSize := rootDisk.Size / 2
+	if err = machineScope.LinodeClient.ResizeInstanceDisk(ctx, linodeInstanceID, rootDiskID, diskSize); err != nil {
+		logger.Error(err, "Failed to resize root disk")
+
+		return err
+	}
+
+	// create the etcd disk
+	etcdDisk, err := machineScope.LinodeClient.CreateInstanceDisk(
+		ctx,
+		linodeInstanceID,
+		linodego.InstanceDiskCreateOptions{
+			Label:      "etcd-data",
+			Size:       diskSize,
+			Filesystem: string(linodego.FilesystemExt4),
+		},
+	)
+	if err != nil {
+		logger.Error(err, "Failed to create etcd disk")
+
+		return err
+	}
+
+	// attach etcd disk to sdc
+	instanceConfig.Devices.SDC = &linodego.InstanceConfigDevice{DiskID: etcdDisk.ID}
+
+	// finally, boot the machine
+	err = machineScope.LinodeClient.BootInstance(ctx, linodeInstanceID, instanceConfig.ID)
+	if err != nil {
+		logger.Error(err, "Failed to boot instance")
+
+		return err
+	}
+
+	return nil
+}
+
 func (r *LinodeMachineReconciler) reconcileUpdate(
 	ctx context.Context,
 	logger logr.Logger,
@@ -451,14 +522,13 @@ func (r *LinodeMachineReconciler) reconcileDelete(
 		return nil
 	}
 
-	err := services.DeleteNodeFromNB(ctx, logger, machineScope)
-	if err != nil {
+	if err := services.DeleteNodeFromNB(ctx, logger, machineScope); err != nil {
 		logger.Error(err, "Failed to remove node from Node Balancer backend")
 
 		return err
 	}
-	err = machineScope.LinodeClient.DeleteInstance(ctx, *machineScope.LinodeMachine.Spec.InstanceID)
-	if err != nil {
+
+	if err := machineScope.LinodeClient.DeleteInstance(ctx, *machineScope.LinodeMachine.Spec.InstanceID); err != nil {
 		if util.IgnoreLinodeAPIError(err, http.StatusNotFound) != nil {
 			logger.Error(err, "Failed to delete Linode machine instance")
 

controller/linodemachine_controller_helpers.go

@@ -57,6 +57,10 @@ func (*LinodeMachineReconciler) newCreateConfig(ctx context.Context, machineScop
 
 		return nil, err
 	}
+
+	// if the machine is a control plane node, further configuration is needed before it can be booted
+	createConfig.Booted = util.Pointer(!kutil.IsControlPlaneMachine(machineScope.Machine))
+
 	createConfig.PrivateIP = true
 
 	bootstrapData, err := machineScope.GetBootstrapData(ctx)
@@ -87,7 +91,6 @@ func (*LinodeMachineReconciler) newCreateConfig(ctx context.Context, machineScop
 	if createConfig.Image == "" {
 		createConfig.Image = reconciler.DefaultMachineControllerLinodeImage
 	}
-
 	if createConfig.RootPass == "" {
 		createConfig.RootPass = uuid.NewString()
 	}

docs/src/SUMMARY.md

@@ -5,6 +5,7 @@
     - [Getting Started](./topics/getting-started.md)
     - [Troubleshooting](./topics/troubleshooting.md)
     - [Addons](./topics/addons.md)
+    - [Etcd](./topics/etcd.md)
 - [Development](./developers/development.md)
     - [Releasing](./developers/releasing.md)
 - [Reference](./reference/reference.md)

docs/src/topics/etcd.md

@@ -0,0 +1,9 @@
+# Etcd
+
+This guide covers etcd configuration for the control plane of provisioned CAPL clusters.
+
+## Default configuration
+
+By default, etcd is configured to be on a separate device from the root filesystem on
+control plane nodes. The etcd disk is automatically sized to take up half of the
+storage on the Linode instance.

templates/flavors/clusterclass-kubeadm/kubeadm-controlplane-template.yaml

@@ -31,12 +31,25 @@ spec:
         preKubeadmCommands:
           - /kubeadm-pre-init.sh '{{ ds.meta_data.label }}' "${KUBERNETES_VERSION}"
         clusterConfiguration:
+          etcd:
+            local:
+              dataDir: /var/lib/etcd_data/etcd
+              extraArgs:
+                quota-backend-bytes: "8589934592"
           apiServer:
             extraArgs:
               cloud-provider: external
           controllerManager:
             extraArgs:
               cloud-provider: external
+        diskSetup:
+          filesystems:
+            - label: etcd_data
+              filesystem: ext4
+              device: /dev/sdc
+        mounts:
+          - - LABEL=etcd_data
+            - /var/lib/etcd_data
         initConfiguration:
           nodeRegistration:
             kubeletExtraArgs:

templates/flavors/default/kubeadm-control-plane.yaml

@@ -36,12 +36,25 @@ spec:
     preKubeadmCommands:
       - /kubeadm-pre-init.sh '{{ ds.meta_data.label }}' "${KUBERNETES_VERSION}"
     clusterConfiguration:
+      etcd:
+        local:
+          dataDir: /var/lib/etcd_data/etcd
+          extraArgs:
+            quota-backend-bytes: "8589934592"
       apiServer:
         extraArgs:
           cloud-provider: external
       controllerManager:
         extraArgs:
           cloud-provider: external
+    diskSetup:
+      filesystems:
+        - label: etcd_data
+          filesystem: ext4
+          device: /dev/sdc
+    mounts:
+      - - LABEL=etcd_data
+        - /var/lib/etcd_data
     initConfiguration:
       nodeRegistration:
         kubeletExtraArgs: