Use local routing in transit gateway when PowerVS and VPC are from same region

api/v1beta2/ibmpowervscluster_types.go

@@ -251,6 +251,11 @@ type TransitGateway struct {
 	// id of resource.
 	// +optional
 	ID *string `json:"id,omitempty"`
+	// globalRouting indicates whether to set global routing true or not while creating the transit gateway.
+	// set this field to true only when PowerVS and VPC are from different regions, if they are same it's suggested to use local routing by setting the field to false.
+	// when the field is omitted,  based on PowerVS region (region associated with IBMPowerVSCluster.Spec.Zone) and VPC region(IBMPowerVSCluster.Spec.VPC.Region) system will decide whether to enable globalRouting or not.
+	// +optional
+	GlobalRouting *bool `json:"globalRouting,omitempty"`
 }
 
 // VPCResourceReference is a reference to a specific VPC resource by ID or Name

cloud/scope/powervs_cluster.go

@@ -1334,16 +1334,26 @@ func (s *PowerVSClusterScope) createTransitGateway() (*string, error) {
 		return nil, fmt.Errorf("error getting resource group id for resource group %v, id is empty", s.ResourceGroup())
 	}
 
-	vpcRegion := s.getVPCRegion()
-	if vpcRegion == nil {
-		return nil, fmt.Errorf("failed to get vpc region")
+	location, globalRouting, err := genUtil.GetTransitGatewayLocationAndRouting(s.Zone(), s.VPC().Region)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get transit gateway location and routing: %w", err)
+	}
+
+	// throw error when user tries to use local routing where global routing is required.
+	// TODO: Add a webhook validation for below condition.
+	if s.IBMPowerVSCluster.Spec.TransitGateway.GlobalRouting != nil && !*s.IBMPowerVSCluster.Spec.TransitGateway.GlobalRouting && *globalRouting {
+		return nil, fmt.Errorf("failed to use local routing for transit gateway since powervs and vpc are in different region and requires global routing")
+	}
+	// setting global routing to true when it is set by user.
+	if s.IBMPowerVSCluster.Spec.TransitGateway.GlobalRouting != nil && *s.IBMPowerVSCluster.Spec.TransitGateway.GlobalRouting {
+		globalRouting = ptr.To(true)
 	}
 
 	tgName := s.GetServiceName(infrav1beta2.ResourceTypeTransitGateway)
 	tg, _, err := s.TransitGatewayClient.CreateTransitGateway(&tgapiv1.CreateTransitGatewayOptions{
-		Location:      vpcRegion,
+		Location:      location,
 		Name:          tgName,
-		Global:        ptr.To(true),
+		Global:        globalRouting,
 		ResourceGroup: &tgapiv1.ResourceGroupIdentity{ID: ptr.To(resourceGroupID)},
 	})
 	if err != nil {
@@ -1744,26 +1754,6 @@ func (s *PowerVSClusterScope) fetchResourceGroupID() (string, error) {
 	return "", err
 }
 
-// getVPCRegion returns region associated with VPC zone.
-func (s *PowerVSClusterScope) getVPCRegion() *string {
-	if s.IBMPowerVSCluster.Spec.VPC != nil {
-		return s.IBMPowerVSCluster.Spec.VPC.Region
-	}
-	// if vpc region is not set try to fetch corresponding region from power vs zone
-	zone := s.Zone()
-	if zone == nil {
-		s.Info("powervs zone is not set")
-		return nil
-	}
-	region := endpoints.ConstructRegionFromZone(*zone)
-	vpcRegion, err := genUtil.VPCRegionForPowerVSRegion(region)
-	if err != nil {
-		s.Error(err, fmt.Sprintf("failed to fetch vpc region associated with powervs region %s", region))
-		return nil
-	}
-	return &vpcRegion
-}
-
 // fetchVPCCRN returns VPC CRN.
 func (s *PowerVSClusterScope) fetchVPCCRN() (*string, error) {
 	vpcID := s.GetVPCID()

config/crd/bases/infrastructure.cluster.x-k8s.io_ibmpowervsclusters.yaml

@@ -396,6 +396,12 @@ spec:
                   when TransitGateway.ID is set, its expected that there exist a TransitGateway with ID or else system will give error.
                   when TransitGateway.Name is set, system will first check for TransitGateway with Name, if not exist system will create new TransitGateway.
                 properties:
+                  globalRouting:
+                    description: |-
+                      globalRouting indicates whether to set global routing true or not while creating the transit gateway.
+                      set this field to true only when PowerVS and VPC are from different regions, if they are same it's suggested to use local routing by setting the field to false.
+                      when the field is omitted,  based on PowerVS region (region associated with IBMPowerVSCluster.Spec.Zone) and VPC region(IBMPowerVSCluster.Spec.VPC.Region) system will decide whether to enable globalRouting or not.
+                    type: boolean
                   id:
                     description: id of resource.
                     type: string

config/crd/bases/infrastructure.cluster.x-k8s.io_ibmpowervsclustertemplates.yaml

@@ -427,6 +427,12 @@ spec:
                           when TransitGateway.ID is set, its expected that there exist a TransitGateway with ID or else system will give error.
                           when TransitGateway.Name is set, system will first check for TransitGateway with Name, if not exist system will create new TransitGateway.
                         properties:
+                          globalRouting:
+                            description: |-
+                              globalRouting indicates whether to set global routing true or not while creating the transit gateway.
+                              set this field to true only when PowerVS and VPC are from different regions, if they are same it's suggested to use local routing by setting the field to false.
+                              when the field is omitted,  based on PowerVS region (region associated with IBMPowerVSCluster.Spec.Zone) and VPC region(IBMPowerVSCluster.Spec.VPC.Region) system will decide whether to enable globalRouting or not.
+                            type: boolean
                           id:
                             description: id of resource.
                             type: string

util/util.go

@@ -21,9 +21,12 @@ import (
 	"fmt"
 	"strconv"
 
+	"k8s.io/utils/ptr"
+
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	infrav1beta2 "sigs.k8s.io/cluster-api-provider-ibmcloud/api/v1beta2"
+	"sigs.k8s.io/cluster-api-provider-ibmcloud/pkg/endpoints"
 )
 
 // GetClusterByName finds and return a Cluster object using the specified params.
@@ -197,3 +200,33 @@ func VPCZonesForPowerVSRegion(region string) ([]string, error) {
 	}
 	return nil, fmt.Errorf("VPC zones corresponding to a PowerVS region %s not found ", region)
 }
+
+// IsGlobalRoutingRequiredForTG returns true when powervs and vpc regions are different.
+func IsGlobalRoutingRequiredForTG(powerVSRegion string, vpcRegion string) bool {
+	if r, ok := Regions[powerVSRegion]; ok && r.VPCRegion == vpcRegion {
+		return false
+	}
+	return true
+}
+
+// GetTransitGatewayLocationAndRouting returns appropriate location and routing suitable for transit gateway.
+// routing indicates whether to enable global routing on transit gateway or not.
+// returns true when PowerVS and VPC region are not same otherwise false.
+func GetTransitGatewayLocationAndRouting(powerVSZone *string, vpcRegion *string) (*string, *bool, error) {
+	if powerVSZone == nil {
+		return nil, nil, fmt.Errorf("powervs zone is not set")
+	}
+	powerVSRegion := endpoints.ConstructRegionFromZone(*powerVSZone)
+
+	if vpcRegion != nil {
+		routing := IsGlobalRoutingRequiredForTG(powerVSRegion, *vpcRegion)
+		return vpcRegion, &routing, nil
+	}
+	location, err := VPCRegionForPowerVSRegion(powerVSRegion)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to fetch vpc region associated with powervs region '%s': %w", powerVSRegion, err)
+	}
+
+	// since VPC region is not set and used PowerVS region to calculate the transit gateway location, hence returning local routing as default.
+	return &location, ptr.To(false), nil
+}