GCP Cluster Manifest: Set Failure Domains

Updates the failure domain logic for the GCP Cluster manifest
so that failure domains are populated only when zones are populated
on both machine pools. Prior to this change, we only checked if the
machine pools were defined, not that the zones were included.

Author: patrickdillon

pkg/asset/manifests/gcp/cluster.go

@@ -137,32 +137,35 @@ func GenerateClusterAssets(installConfig *installconfig.InstallConfig, clusterID
 // only use zones if both the compute and control plane node availability zones exist.
 func findFailureDomains(installConfig *installconfig.InstallConfig) []string {
 	zones := sets.New[string]()
-	defaultMachinePlatformDefined := false
-	if gcpPlatform := installConfig.Config.Platform.GCP; gcpPlatform != nil && gcpPlatform.DefaultMachinePlatform != nil {
-		defaultMachinePlatformDefined = true
-		for _, zone := range gcpPlatform.DefaultMachinePlatform.Zones {
+
+	var controlPlaneZones, computeZones []string
+	if installConfig.Config.ControlPlane.Platform.GCP != nil {
+		controlPlaneZones = installConfig.Config.ControlPlane.Platform.GCP.Zones
+	}
+
+	if installConfig.Config.Compute[0].Platform.GCP != nil {
+		computeZones = installConfig.Config.Compute[0].Platform.GCP.Zones
+	}
+
+	def := installConfig.Config.GCP.DefaultMachinePlatform
+	if def != nil && len(def.Zones) > 0 {
+		for _, zone := range def.Zones {
+			zones.Insert(zone)
+		}
+
+		for _, zone := range controlPlaneZones {
 			zones.Insert(zone)
 		}
 
-		if installConfig.Config.ControlPlane.Platform.GCP != nil {
-			for _, zone := range installConfig.Config.ControlPlane.Platform.GCP.Zones {
-				zones.Insert(zone)
-			}
+		for _, zone := range computeZones {
+			zones.Insert(zone)
 		}
-		if installConfig.Config.Compute[0].Platform.GCP != nil {
-			for _, zone := range installConfig.Config.Compute[0].Platform.GCP.Zones {
-				zones.Insert(zone)
-			}
+	} else if len(controlPlaneZones) > 0 && len(computeZones) > 0 {
+		for _, zone := range controlPlaneZones {
+			zones.Insert(zone)
 		}
-	}
-	if !defaultMachinePlatformDefined {
-		if installConfig.Config.ControlPlane.Platform.GCP != nil && installConfig.Config.Compute[0].Platform.GCP != nil {
-			for _, zone := range installConfig.Config.ControlPlane.Platform.GCP.Zones {
-				zones.Insert(zone)
-			}
-			for _, zone := range installConfig.Config.Compute[0].Platform.GCP.Zones {
-				zones.Insert(zone)
-			}
+		for _, zone := range computeZones {
+			zones.Insert(zone)
 		}
 	}