Add SubnetIDs field to support multiple subnets for machine instances (gardener#347)

* Add SubnetIDs field to support multiple subnets for machine instances

* make SubnetIDs optional

Author: axel7born

hack/api-reference/api.md

@@ -145,7 +145,20 @@ string
 </td>
 <td>
 <em>(Optional)</em>
-<p>SubnetID is the ID of the subnet the instance should belong to. If SubnetID is not specified</p>
+<p>SubnetID is the ID of the subnet the instance should belong to.
+Deprecated - use <code>SubnetIDs</code> instead.</p>
+</td>
+</tr>
+<tr>
+<td>
+<code>subnetIDs</code></br>
+<em>
+[]string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>SubnetIDs is a list of IDs of the subnets the instance should belong to.</p>
 </td>
 </tr>
 <tr>
@@ -363,7 +376,20 @@ string
 </td>
 <td>
 <em>(Optional)</em>
-<p>SubnetID is the ID of the subnet the instance should belong to. If SubnetID is not specified</p>
+<p>SubnetID is the ID of the subnet the instance should belong to.
+Deprecated - use <code>SubnetIDs</code> instead.</p>
+</td>
+</tr>
+<tr>
+<td>
+<code>subnetIDs</code></br>
+<em>
+[]string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>SubnetIDs is a list of IDs of the subnets the instance should belong to.</p>
 </td>
 </tr>
 <tr>

pkg/apis/openstack/types.go

@@ -37,8 +37,11 @@ type MachineProviderConfigSpec struct {
 	Tags map[string]string
 	// NetworkID is the ID of the network the instance should belong to.
 	NetworkID string
-	// SubnetID is the ID of the subnet the instance should belong to. If SubnetID is not specified
+	// SubnetID is the ID of the subnet the instance should belong to.
+	// Deprecated - use `SubnetIDs` instead.
 	SubnetID *string
+	// SubnetIDs is a list of IDs of the subnets the instance should belong to.
+	SubnetIDs []string
 	// PodNetworkCidr is the CIDR range for the pods assigned to this instance.
 	// Deprecated - use `PodNetworkCIDRs` instead.
 	PodNetworkCidr string

pkg/apis/openstack/v1alpha1/types.go

@@ -39,9 +39,13 @@ type MachineProviderConfigSpec struct {
 	Tags map[string]string `json:"tags,omitempty"`
 	// NetworkID is the ID of the network the instance should belong to.
 	NetworkID string `json:"networkID"`
-	// SubnetID is the ID of the subnet the instance should belong to. If SubnetID is not specified
+	// SubnetID is the ID of the subnet the instance should belong to.
+	// Deprecated - use `SubnetIDs` instead.
 	// +optional
 	SubnetID *string `json:"subnetID,omitempty"`
+	// SubnetIDs is a list of IDs of the subnets the instance should belong to.
+	// +optional
+	SubnetIDs []string `json:"subnetIDs,omitempty"`
 	// PodNetworkCidr is the CIDR range for the pods assigned to this instance.
 	// Deprecated: use PodNetworkCIDRs instead
 	// +optional

pkg/apis/openstack/v1alpha1/zz_generated.conversion.go

@@ -574,7 +574,7 @@ func (ex *Executor) getOrCreatePort(ctx context.Context, machineName string) (st
 	port, err := ex.Network.CreatePort(ctx, &ports.CreateOpts{
 		Name:           machineName,
 		NetworkID:      ex.Config.Spec.NetworkID,
-		FixedIPs:       []ports.IP{{SubnetID: *ex.Config.Spec.SubnetID}},
+		FixedIPs:       ex.buildFixedIPs(),
 		SecurityGroups: &securityGroupIDs,
 	})
 	if err != nil {
@@ -596,6 +596,32 @@ func (ex *Executor) getOrCreatePort(ctx context.Context, machineName string) (st
 	return port.ID, nil
 }
 
+// buildFixedIPs creates a list of FixedIPs from SubnetID and SubnetIDs, avoiding duplicates
+func (ex *Executor) buildFixedIPs() []ports.IP {
+	// Use a set to track unique subnet IDs and avoid duplicates
+	subnetIDSet := sets.NewString()
+
+	// Add the single SubnetID if specified
+	if ex.Config.Spec.SubnetID != nil && *ex.Config.Spec.SubnetID != "" {
+		subnetIDSet.Insert(*ex.Config.Spec.SubnetID)
+	}
+
+	// Add all SubnetIDs if specified
+	for _, subnetID := range ex.Config.Spec.SubnetIDs {
+		if subnetID != "" {
+			subnetIDSet.Insert(subnetID)
+		}
+	}
+
+	// Convert to []ports.IP
+	var fixedIPs []ports.IP
+	for _, subnetID := range subnetIDSet.List() {
+		fixedIPs = append(fixedIPs, ports.IP{SubnetID: subnetID})
+	}
+
+	return fixedIPs
+}
+
 func (ex *Executor) deletePort(ctx context.Context, machineName string) error {
 	portList, err := ex.Network.ListPorts(ctx, ports.ListOpts{
 		Name: machineName,
@@ -752,5 +778,9 @@ func (ex *Executor) listServers(ctx context.Context) ([]servers.Server, error) {
 
 // isUserManagedNetwork returns true if the port used by the machine will be created and managed by MCM.
 func (ex *Executor) isUserManagedNetwork() bool {
-	return !isEmptyString(ptr.To(ex.Config.Spec.NetworkID)) && !isEmptyString(ex.Config.Spec.SubnetID)
+	hasNetworkID := !isEmptyString(ptr.To(ex.Config.Spec.NetworkID))
+	hasSubnetID := !isEmptyString(ex.Config.Spec.SubnetID)
+	hasSubnetIDs := len(ex.Config.Spec.SubnetIDs) > 0
+
+	return hasNetworkID && (hasSubnetID || hasSubnetIDs)
 }