Implement deletion lifecycle hooks

api/v1alpha3/machine_types.go

@@ -37,6 +37,18 @@ const (
 
 	// MachineDeploymentLabelName is the label set on machines if they're controlled by MachineDeployment
 	MachineDeploymentLabelName = "cluster.x-k8s.io/deployment-name"
+
+	// PreDrainDeleteHookAnnotationPrefix annotation specifies the prefix we
+	// search each annotation for during the pre-drain.delete lifecycle hook
+	// to pause reconciliation of deletion. These hooks will prevent removal of
+	// draining the associated node until all are removed.
+	PreDrainDeleteHookAnnotationPrefix = "pre-drain.delete.hook.machine.cluster.x-k8s.io"
+
+	// PreTerminateDeleteHookAnnotationPrefix annotation specifies the prefix we
+	// search each annotation for during the pre-terminate.delete lifecycle hook
+	// to pause reconciliation of deletion. These hooks will prevent removal of
+	// an instance from an infrastructure provider until all are removed.
+	PreTerminateDeleteHookAnnotationPrefix = "pre-terminate.delete.hook.machine.cluster.x-k8s.io"
 )
 
 // ANCHOR: MachineSpec

controllers/machine_controller.go

@@ -19,6 +19,7 @@ package controllers
 import (
 	"context"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/go-logr/logr"
@@ -290,6 +291,11 @@ func (r *MachineReconciler) reconcileDelete(ctx context.Context, cluster *cluste
 	}
 
 	if isDeleteNodeAllowed {
+		// pre-drain.delete lifecycle hook
+		// Return early without error, will requeue if/when the Hook is removed.
+		if waitForHook(clusterv1.PreDrainDeleteHookAnnotationPrefix, m.ObjectMeta.Annotations) {
+			return ctrl.Result{}, nil
+		}
 		// Drain node before deletion.
 		if _, exists := m.ObjectMeta.Annotations[clusterv1.ExcludeNodeDrainingAnnotation]; !exists {
 			logger.Info("Draining node", "node", m.Status.NodeRef.Name)
@@ -301,6 +307,12 @@ func (r *MachineReconciler) reconcileDelete(ctx context.Context, cluster *cluste
 		}
 	}
 
+	// pre-term.delete lifecycle hook
+	// Return early without error, will requeue if/when the Hook is removed.
+	if waitForHook(clusterv1.PreTerminateDeleteHookAnnotationPrefix, m.ObjectMeta.Annotations) {
+		return ctrl.Result{}, nil
+	}
+
 	if ok, err := r.reconcileDeleteExternal(ctx, m); !ok || err != nil {
 		// Return early and don't remove the finalizer if we got an error or
 		// the external reconciliation deletion isn't ready.
@@ -491,6 +503,15 @@ func (r *MachineReconciler) shouldAdopt(m *clusterv1.Machine) bool {
 	return metav1.GetControllerOf(m) == nil && !util.HasOwner(m.OwnerReferences, clusterv1.GroupVersion.String(), []string{"Cluster"})
 }
 
+func waitForHook(hookName string, annotations map[string]string) bool {
+	for key := range annotations {
+		if strings.HasPrefix(key, hookName) {
+			return true
+		}
+	}
+	return false
+}
+
 // writer implements io.Writer interface as a pass-through for klog.
 type writer struct {
 	logFunc func(args ...interface{})