CORS-2895: aws/capi: decouple the zone config

Moving the cluster subnet configuration for CAPI to a dedicated file
decoupling the functions for BYOVPC and managed VPC to dedicated
functions to create tests dedicated for each scenario.

The subnet structure created in managed VPC by CAPA is created with
SubnetSpec, without providing the valid ID, so CAPA will understand that
the subnet does not exists and will created it following the zone
specified/discovered in the install config.

pkg/asset/manifests/aws/cluster.go

@@ -1,11 +1,9 @@
 package aws
 
 import (
-	"context"
 	"fmt"
 	"time"
 
-	"github.com/pkg/errors"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/utils/ptr"
@@ -19,33 +17,24 @@ import (
 )
 
 // GenerateClusterAssets generates the manifests for the cluster-api.
-func GenerateClusterAssets(installConfig *installconfig.InstallConfig, clusterID *installconfig.ClusterID) (*capiutils.GenerateClusterAssetsOutput, error) {
+func GenerateClusterAssets(ic *installconfig.InstallConfig, clusterID *installconfig.ClusterID) (*capiutils.GenerateClusterAssetsOutput, error) {
 	manifests := []*asset.RuntimeFile{}
-	mainCIDR := capiutils.CIDRFromInstallConfig(installConfig)
 
-	zones, err := installConfig.AWS.AvailabilityZones(context.TODO())
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to get availability zones")
-	}
-
-	tags, err := aws.CapaTagsFromUserTags(clusterID.InfraID, installConfig.Config.AWS.UserTags)
+	tags, err := aws.CapaTagsFromUserTags(clusterID.InfraID, ic.Config.AWS.UserTags)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get user tags: %w", err)
 	}
 
+	mainCIDR := capiutils.CIDRFromInstallConfig(ic)
+
 	awsCluster := &capa.AWSCluster{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      clusterID.InfraID,
 			Namespace: capiutils.Namespace,
 		},
 		Spec: capa.AWSClusterSpec{
-			Region: installConfig.Config.AWS.Region,
+			Region: ic.Config.AWS.Region,
 			NetworkSpec: capa.NetworkSpec{
-				VPC: capa.VPCSpec{
-					CidrBlock:                  mainCIDR.String(),
-					AvailabilityZoneUsageLimit: ptr.To(len(zones)),
-					AvailabilityZoneSelection:  &capa.AZSelectionSchemeOrdered,
-				},
 				CNI: &capa.CNISpec{
 					CNIIngressRules: capa.CNIIngressRules{
 						{
@@ -182,7 +171,7 @@ func GenerateClusterAssets(installConfig *installconfig.InstallConfig, clusterID
 		},
 	}
 
-	if installConfig.Config.Publish == types.ExternalPublishingStrategy {
+	if ic.Config.Publish == types.ExternalPublishingStrategy {
 		// FIXME: CAPA bug. Remove when fixed upstream
 		// The primary and secondary load balancers in CAPA share the same
 		// security group. However, specifying an ingress rule only in the
@@ -217,41 +206,17 @@ func GenerateClusterAssets(installConfig *installconfig.InstallConfig, clusterID
 		}
 	}
 
-	// If the install config has subnets, use them.
-	if len(installConfig.AWS.Subnets) > 0 {
-		privateSubnets, err := installConfig.AWS.PrivateSubnets(context.TODO())
-		if err != nil {
-			return nil, errors.Wrap(err, "failed to get private subnets")
-		}
-		for _, subnet := range privateSubnets {
-			awsCluster.Spec.NetworkSpec.Subnets = append(awsCluster.Spec.NetworkSpec.Subnets, capa.SubnetSpec{
-				ID:               subnet.ID,
-				CidrBlock:        subnet.CIDR,
-				AvailabilityZone: subnet.Zone.Name,
-				IsPublic:         subnet.Public,
-			})
-		}
-		publicSubnets, err := installConfig.AWS.PublicSubnets(context.TODO())
-		if err != nil {
-			return nil, errors.Wrap(err, "failed to get public subnets")
-		}
-
-		for _, subnet := range publicSubnets {
-			awsCluster.Spec.NetworkSpec.Subnets = append(awsCluster.Spec.NetworkSpec.Subnets, capa.SubnetSpec{
-				ID:               subnet.ID,
-				CidrBlock:        subnet.CIDR,
-				AvailabilityZone: subnet.Zone.Name,
-				IsPublic:         subnet.Public,
-			})
-		}
-
-		vpc, err := installConfig.AWS.VPC(context.TODO())
-		if err != nil {
-			return nil, errors.Wrap(err, "failed to get VPC")
-		}
-		awsCluster.Spec.NetworkSpec.VPC = capa.VPCSpec{
-			ID: vpc,
-		}
+	// Set the VPC and zones (managed) or subnets (BYO VPC) based in the
+	// install-config.yaml.
+	err = setZones(&zoneConfigInput{
+		InstallConfig: ic,
+		Config:        ic.Config,
+		Meta:          ic.AWS,
+		ClusterID:     clusterID,
+		Cluster:       awsCluster,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to set cluster zones or subnets: %w", err)
 	}
 
 	manifests = append(manifests, &asset.RuntimeFile{