Support External Cloud Provider

pkg/cloudprovider/provider.go

@@ -28,6 +28,7 @@ import (
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/digitalocean"
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/edge"
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/equinixmetal"
+	"k8c.io/machine-controller/pkg/cloudprovider/provider/external"
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/fake"
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/gce"
 	"k8c.io/machine-controller/pkg/cloudprovider/provider/hetzner"
@@ -111,6 +112,9 @@ var (
 		providerconfigtypes.CloudProviderVMwareCloudDirector: func(cvr *providerconfig.ConfigVarResolver) cloudprovidertypes.Provider {
 			return vcd.New(cvr)
 		},
+		providerconfigtypes.CloudProviderExternal: func(cvr *providerconfig.ConfigVarResolver) cloudprovidertypes.Provider {
+			return external.New(cvr)
+		},
 	}
 
 	// communityProviders holds a map of cloud providers that have been implemented by community members and

pkg/cloudprovider/provider/external/provider.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2025 The Machine Controller Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package external
+
+import (
+	"context"
+	"go.uber.org/zap"
+
+	clusterv1alpha1 "k8c.io/machine-controller/pkg/apis/cluster/v1alpha1"
+	"k8c.io/machine-controller/pkg/cloudprovider/instance"
+	cloudprovidertypes "k8c.io/machine-controller/pkg/cloudprovider/types"
+	"k8c.io/machine-controller/pkg/providerconfig"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+type provider struct{}
+
+type CloudProviderSpec struct {
+}
+
+type CloudProviderInstance struct{}
+
+func (f CloudProviderInstance) Name() string {
+	return ""
+}
+
+func (f CloudProviderInstance) ID() string {
+	return ""
+}
+
+func (f CloudProviderInstance) ProviderID() string {
+	return ""
+}
+
+func (f CloudProviderInstance) Addresses() map[string]corev1.NodeAddressType {
+	return nil
+}
+
+func (f CloudProviderInstance) Status() instance.Status {
+	return instance.StatusUnknown
+}
+
+// New returns an external cloud provider.
+func New(_ *providerconfig.ConfigVarResolver) cloudprovidertypes.Provider {
+	return &provider{}
+}
+
+func (p *provider) AddDefaults(_ *zap.SugaredLogger, spec clusterv1alpha1.MachineSpec) (clusterv1alpha1.MachineSpec, error) {
+	return spec, nil
+}
+
+// Validate returns success or failure based according to its ExternalCloudProviderSpec.
+func (p *provider) Validate(_ context.Context, _ *zap.SugaredLogger, _ clusterv1alpha1.MachineSpec) error {
+	return nil
+}
+
+func (p *provider) Get(_ context.Context, _ *zap.SugaredLogger, _ *clusterv1alpha1.Machine, _ *cloudprovidertypes.ProviderData) (instance.Instance, error) {
+	return CloudProviderInstance{}, nil
+}
+
+// Create creates a cloud instance according to the given machine.
+func (p *provider) Create(_ context.Context, _ *zap.SugaredLogger, _ *clusterv1alpha1.Machine, _ *cloudprovidertypes.ProviderData, _ string) (instance.Instance, error) {
+	return CloudProviderInstance{}, nil
+}
+
+func (p *provider) Cleanup(_ context.Context, _ *zap.SugaredLogger, _ *clusterv1alpha1.Machine, _ *cloudprovidertypes.ProviderData) (bool, error) {
+	return true, nil
+}
+
+func (p *provider) MigrateUID(_ context.Context, _ *zap.SugaredLogger, _ *clusterv1alpha1.Machine, _ types.UID) error {
+	return nil
+}
+
+func (p *provider) MachineMetricsLabels(_ *clusterv1alpha1.Machine) (map[string]string, error) {
+	return map[string]string{}, nil
+}
+
+func (p *provider) SetMetricsForMachines(_ clusterv1alpha1.MachineList) error {
+	return nil
+}

pkg/controller/machine/controller.go

@@ -751,8 +751,14 @@ func (r *Reconciler) deleteCloudProviderInstance(ctx context.Context, log *zap.S
 
 	return nil, r.updateMachine(machine, func(m *clusterv1alpha1.Machine) {
 		finalizers := sets.NewString(m.Finalizers...)
-		finalizers.Delete(FinalizerDeleteInstance)
-		m.Finalizers = finalizers.List()
+		// If a machine deployment belongs to an external cloud provider, the 'machine-delete-finalizer' must be manually
+		// removed by an administrator or an external service. This is because the machine controller lacks access to cloud
+		// instances and cannot ensure their deletion. If the external service fails to delete the instance, it may result
+		// in orphaned resources or nodes without a machine reference.
+		if machineConfig.CloudProvider != providerconfigtypes.CloudProviderExternal {
+			finalizers.Delete(FinalizerDeleteInstance)
+			m.Finalizers = finalizers.List()
+		}
 	})
 }
 

pkg/providerconfig/types/types.go

@@ -113,6 +113,7 @@ var (
 		CloudProviderBaremetal,
 		CloudProviderVultr,
 		CloudProviderOpenNebula,
+		CloudProviderExternal,
 	}
 )