fix: make vlan tag ids configurable

Resolves: #1236

Author: dmacvicar

internal/codegen/docs/domain.yaml

@@ -6360,7 +6360,7 @@ entries:
     description: Sets an opaque interface identifier for the virtual port profile, typically used by SDN or virtual switch controllers; value is user-provided (often a UUID or similar).
     reference: https://libvirt.org/formatdomain.html#virtual-network
   - path: domain.devices.interfaces.vlan.tags.id
-    description: Reports the VLAN ID associated with this tag; this is computed from the underlying XML and must be a valid VLAN tag (typically in the range 1–4094).
+    description: Sets the VLAN ID associated with this tag; value is user-provided and must be a valid VLAN tag for the interface configuration.
     reference: https://libvirt.org/formatdomain.html#setting-vlan-tag-on-supported-network-types-only
   - path: domain.devices.interfaces.virtual_port.params.mido_net.interface_id
     description: Sets the Midonet virtual interface identifier associated with this NIC; the value is user-provided and must match the interface ID configured in Midonet.

internal/codegen/docs/network.yaml

@@ -363,7 +363,7 @@ entries:
     description: Sets the Open vSwitch profile identifier (profileid) for ports in this portgroup; value is user-provided and used by OVS or higher-level controllers to apply a specific port profile.
     reference: https://libvirt.org/formatdomain.html#virtual-network
   - path: network.port_groups.vlan.tags.id
-    description: Reports the VLAN ID associated with this tag; when managed by libvirt it is computed from the backing XML and corresponds to the 802.1Q VLAN identifier (1–4094).
+    description: Sets the VLAN ID associated with this tag; value is user-provided and corresponds to the 802.1Q VLAN identifier used for this network or portgroup.
     reference: https://libvirt.org/formatnetwork.html#setting-vlan-tag-on-supported-network-types-only
   - path: network.routes.address
     description: Sets the destination network address (in IPv4 or IPv6 form) for this static route; value is user-provided and should match the route’s prefix (e.g. "192.168.2.0/24" or "2001:db8::/64").
@@ -492,7 +492,7 @@ entries:
     description: Sets the VEPA 802.1Qbg VSI type ID, indicating the profile or type assigned to this virtual interface; value is user-provided, typically a numeric profile identifier from the network policy.
     reference: https://libvirt.org/formatnetwork.html#connectivity
   - path: network.vlan.tags.id
-    description: Reports the VLAN ID for this tag entry; this is computed from libvirt and corresponds to a numeric VLAN identifier between 1 and 4094.
+    description: Sets the VLAN ID for this tag entry; value is user-provided and corresponds to the numeric VLAN identifier applied to this network.
     reference: https://libvirt.org/formatnetwork.html#setting-vlan-tag-on-supported-network-types-only
   - path: network.virtual_port.params.vepa8021qbg.manager_id
     description: Sets the VEPA 802.1Qbg manager ID that identifies the VSI manager (e.g., a switch or controller) responsible for this interface; value is user-provided according to the physical network’s configuration.

internal/codegen/parser/libvirtxml.go

@@ -183,6 +183,14 @@ func (r *LibvirtXMLReflector) applyFieldPatterns(structName string, fields []*ge
 		// Universal patterns (apply to ALL resources)
 		switch field.TFName {
 		case "uuid", "id", "key":
+			if field.TFName == "id" && isUserManagedVLANTagIDStruct(structName) {
+				field.IsComputed = false
+				field.IsOptional = false
+				field.IsRequired = true
+				field.PlanModifier = "RequiresReplace"
+				continue
+			}
+
 			field.IsComputed = true
 			field.IsOptional = false
 			field.IsRequired = false
@@ -257,6 +265,15 @@ func (r *LibvirtXMLReflector) applyFieldPatterns(structName string, fields []*ge
 	}
 }
 
+func isUserManagedVLANTagIDStruct(structName string) bool {
+	switch structName {
+	case "NetworkVLANTag", "DomainInterfaceVLanTag", "NetworkPortVLANTag":
+		return true
+	default:
+		return false
+	}
+}
+
 func (r *LibvirtXMLReflector) analyzeField(structName string, field reflect.StructField) (*generator.FieldIR, error) {
 	// Skip XMLName fields (used by encoding/xml)
 	if field.Name == "XMLName" {

internal/regression/vlan_tag_schema_test.go

@@ -0,0 +1,48 @@
+package regression
+
+import (
+	"testing"
+
+	"github.com/dmacvicar/terraform-provider-libvirt/v2/internal/generated"
+	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
+)
+
+func TestNetworkVLANTagIDIsRequired(t *testing.T) {
+	attr := generated.NetworkVLANTagSchemaAttribute()
+	nested, ok := attr.(schema.SingleNestedAttribute)
+	if !ok {
+		t.Fatalf("expected SingleNestedAttribute, got %T", attr)
+	}
+
+	idAttr, ok := nested.Attributes["id"].(schema.Int64Attribute)
+	if !ok {
+		t.Fatalf("expected Int64Attribute for network VLAN tag id, got %T", nested.Attributes["id"])
+	}
+
+	if !idAttr.Required {
+		t.Fatal("expected network VLAN tag id to be required")
+	}
+	if idAttr.Computed {
+		t.Fatal("expected network VLAN tag id to not be computed")
+	}
+}
+
+func TestDomainInterfaceVLanTagIDIsRequired(t *testing.T) {
+	attr := generated.DomainInterfaceVLanTagSchemaAttribute()
+	nested, ok := attr.(schema.SingleNestedAttribute)
+	if !ok {
+		t.Fatalf("expected SingleNestedAttribute, got %T", attr)
+	}
+
+	idAttr, ok := nested.Attributes["id"].(schema.Int64Attribute)
+	if !ok {
+		t.Fatalf("expected Int64Attribute for domain interface VLAN tag id, got %T", nested.Attributes["id"])
+	}
+
+	if !idAttr.Required {
+		t.Fatal("expected domain interface VLAN tag id to be required")
+	}
+	if idAttr.Computed {
+		t.Fatal("expected domain interface VLAN tag id to not be computed")
+	}
+}