Verify machine-controller CRDs before deleting workers (kubermatic#683)

* Verify machine-controller CRDs before deleting workers

* Ignore unparam lint error for defaultRetryBackoff

.golangci.yml

@@ -33,3 +33,4 @@ issues:
     - "don't use underscores in Go names; func SetDefaults_SystemPackages should be SetDefaultsSystemPackages"
     - "G101: Potential hardcoded credentials"
     - "G106: Use of ssh InsecureIgnoreHostKey should be audited"
+    - "`defaultRetryBackoff` - `retries` always receives `3`"

pkg/installer/installation/reset.go

@@ -73,6 +73,18 @@ func destroyWorkers(s *state.State) error {
 		return errors.Wrap(lastErr, "unable to build kubernetes clientset")
 	}
 
+	_ = wait.ExponentialBackoff(defaultRetryBackoff(3), func() (bool, error) {
+		lastErr = machinecontroller.VerifyCRDs(s)
+		if lastErr != nil {
+			return false, nil
+		}
+		return true, nil
+	})
+	if lastErr != nil {
+		s.Logger.Info("Skipping deleting worker nodes because machine-controller CRDs are not deployed")
+		return nil
+	}
+
 	_ = wait.ExponentialBackoff(defaultRetryBackoff(3), func() (bool, error) {
 		lastErr = machinecontroller.DestroyWorkers(s)
 		if lastErr != nil {

pkg/templates/machinecontroller/helper.go

@@ -25,6 +25,7 @@ import (
 	"github.com/kubermatic/kubeone/pkg/state"
 
 	corev1 "k8s.io/api/core/v1"
+	apiextensions "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
 	errorsutil "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/util/retry"
@@ -73,6 +74,32 @@ func WaitReady(s *state.State) error {
 	return nil
 }
 
+// VerifyCRDs verifies are Cluster-API CRDs deployed
+func VerifyCRDs(s *state.State) error {
+	bgCtx := context.Background()
+	crd := &apiextensions.CustomResourceDefinition{}
+
+	// Verify MachineDeployment CRD
+	key := dynclient.ObjectKey{Name: "machinedeployments.cluster.k8s.io"}
+	if err := s.DynamicClient.Get(bgCtx, key, crd); err != nil {
+		return errors.Wrap(err, "MachineDeployments CRD is not deployed")
+	}
+
+	// Verify MachineSet CRD
+	key = dynclient.ObjectKey{Name: "machinesets.cluster.k8s.io"}
+	if err := s.DynamicClient.Get(bgCtx, key, crd); err != nil {
+		return errors.Wrap(err, "MachineSet CRD is not deployed")
+	}
+
+	// Verify Machine CRD
+	key = dynclient.ObjectKey{Name: "machines.cluster.k8s.io"}
+	if err := s.DynamicClient.Get(bgCtx, key, crd); err != nil {
+		return errors.Wrap(err, "MachineSet CRD is not deployed")
+	}
+
+	return nil
+}
+
 // DestroyWorkers destroys all MachineDeployment, MachineSet and Machine objects
 func DestroyWorkers(s *state.State) error {
 	if !s.Cluster.MachineController.Deploy {
@@ -116,11 +143,9 @@ func DestroyWorkers(s *state.State) error {
 	s.Logger.Info("Deleting MachineDeployment objects…")
 	mdList := &clusterv1alpha1.MachineDeploymentList{}
 	if err := s.DynamicClient.List(bgCtx, dynclient.InNamespace(MachineControllerNamespace), mdList); err != nil {
-		if errorsutil.IsTimeout(err) || errorsutil.IsServerTimeout(err) {
+		if !errorsutil.IsNotFound(err) {
 			return errors.Wrap(err, "unable to list machinedeployment objects")
 		}
-		s.Logger.Info("Skipping deleting worker nodes because MachineDeployments CRD is not deployed")
-		return nil
 	}
 	for i := range mdList.Items {
 		if err := s.DynamicClient.Delete(bgCtx, &mdList.Items[i]); err != nil {