fix: region handling in routingtable resources didn't detect default_region changes (#1006)

stackit/internal/services/iaasalpha/routingtable/route/resource.go

@@ -31,6 +31,7 @@ var (
 	_ resource.Resource                = &routeResource{}
 	_ resource.ResourceWithConfigure   = &routeResource{}
 	_ resource.ResourceWithImportState = &routeResource{}
+	_ resource.ResourceWithModifyPlan  = &routeResource{}
 )
 
 // NewRoutingTableRouteResource is a helper function to simplify the provider implementation.
@@ -70,6 +71,36 @@ func (r *routeResource) Configure(ctx context.Context, req resource.ConfigureReq
 	tflog.Info(ctx, "IaaS alpha client configured")
 }
 
+// ModifyPlan implements resource.ResourceWithModifyPlan.
+// Use the modifier to set the effective region in the current plan.
+func (r *routeResource) ModifyPlan(ctx context.Context, req resource.ModifyPlanRequest, resp *resource.ModifyPlanResponse) { // nolint:gocritic // function signature required by Terraform
+	// skip initial empty configuration to avoid follow-up errors
+	if req.Config.Raw.IsNull() {
+		return
+	}
+
+	var configModel shared.RouteModel
+	resp.Diagnostics.Append(req.Config.Get(ctx, &configModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+	var planModel shared.RouteModel
+	resp.Diagnostics.Append(req.Plan.Get(ctx, &planModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	utils.AdaptRegion(ctx, configModel.Region, &planModel.Region, r.providerData.GetRegion(), resp)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	resp.Diagnostics.Append(resp.Plan.Set(ctx, planModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+}
+
 // Schema defines the schema for the resource.
 func (r *routeResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
 	description := "Routing table route resource schema. Must have a `region` specified in the provider configuration."

stackit/internal/services/iaasalpha/routingtable/table/resource.go

@@ -8,7 +8,6 @@ import (
 	"time"
 
 	"github.com/hashicorp/terraform-plugin-framework/resource/schema/booldefault"
-
 	"github.com/hashicorp/terraform-plugin-framework/resource/schema/boolplanmodifier"
 
 	iaasUtils "github.com/stackitcloud/terraform-provider-stackit/stackit/internal/services/iaas/utils"
@@ -36,6 +35,7 @@ var (
 	_ resource.Resource                = &routingTableResource{}
 	_ resource.ResourceWithConfigure   = &routingTableResource{}
 	_ resource.ResourceWithImportState = &routingTableResource{}
+	_ resource.ResourceWithModifyPlan  = &routingTableResource{}
 )
 
 type Model struct {
@@ -89,6 +89,36 @@ func (r *routingTableResource) Configure(ctx context.Context, req resource.Confi
 	tflog.Info(ctx, "IaaS alpha client configured")
 }
 
+// ModifyPlan implements resource.ResourceWithModifyPlan.
+// Use the modifier to set the effective region in the current plan.
+func (r *routingTableResource) ModifyPlan(ctx context.Context, req resource.ModifyPlanRequest, resp *resource.ModifyPlanResponse) { // nolint:gocritic // function signature required by Terraform
+	// skip initial empty configuration to avoid follow-up errors
+	if req.Config.Raw.IsNull() {
+		return
+	}
+	var configModel Model
+	resp.Diagnostics.Append(req.Config.Get(ctx, &configModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	var planModel Model
+	resp.Diagnostics.Append(req.Plan.Get(ctx, &planModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	utils.AdaptRegion(ctx, configModel.Region, &planModel.Region, r.providerData.GetRegion(), resp)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	resp.Diagnostics.Append(resp.Plan.Set(ctx, planModel)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+}
+
 func (r *routingTableResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
 	description := "Routing table resource schema. Must have a `region` specified in the provider configuration."
 	resp.Schema = schema.Schema{