Allow for omiting AZ from control plane nodes

Author: Matt Pryor

api/v1alpha6/openstackcluster_types.go

@@ -129,6 +129,10 @@ type OpenStackClusterSpec struct {
 	// +listType=set
 	ControlPlaneAvailabilityZones []string `json:"controlPlaneAvailabilityZones,omitempty"`
 
+	// Indicates whether to omit the az for control plane nodes, allowing the Nova scheduler
+	// to make a decision on which az to use based on other scheduling constraints
+	ControlPlaneOmitAvailabilityZone bool `json:"controlPlaneOmitAvailabilityZone,omitempty"`
+
 	// Bastion is the OpenStack instance to login the nodes
 	//
 	// As a rolling update is not ideal during a bastion host session, we

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

@@ -4728,6 +4728,11 @@ spec:
                 - host
                 - port
                 type: object
+              controlPlaneOmitAvailabilityZone:
+                description: Indicates whether to omit the az for control plane nodes,
+                  allowing the Nova scheduler to make a decision on which az to use
+                  based on other scheduling constraints
+                type: boolean
               disableAPIServerFloatingIP:
                 description: DisableAPIServerFloatingIP determines whether or not
                   to attempt to attach a floating IP to the API server. This allows

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

@@ -1966,6 +1966,11 @@ spec:
                         - host
                         - port
                         type: object
+                      controlPlaneOmitAvailabilityZone:
+                        description: Indicates whether to omit the az for control
+                          plane nodes, allowing the Nova scheduler to make a decision
+                          on which az to use based on other scheduling constraints
+                        type: boolean
                       disableAPIServerFloatingIP:
                         description: DisableAPIServerFloatingIP determines whether
                           or not to attempt to attach a floating IP to the API server.

controllers/openstackcluster_controller.go

@@ -280,21 +280,16 @@ func reconcileNormal(ctx context.Context, scope *scope.Scope, patchHelper *patch
 		return ctrl.Result{}, err
 	}
 
-	// Create a new list to remove any Availability
-	// Zones that have been removed from OpenStack
+	// Create a new list in case any AZs have been removed from OpenStack
 	openStackCluster.Status.FailureDomains = make(clusterv1.FailureDomains)
 	for _, az := range availabilityZones {
-		found := true
-		// If Az given, then check whether it's in the allow list
-		// If no Az given, then by default put into allow list
+		// By default, the AZ is used or not used for control plane nodes depending on the flag
+		found := !openStackCluster.Spec.ControlPlaneOmitAvailabilityZone
+		// If explicit AZs for control plane nodes are given, they override the value
 		if len(openStackCluster.Spec.ControlPlaneAvailabilityZones) > 0 {
-			if contains(openStackCluster.Spec.ControlPlaneAvailabilityZones, az.ZoneName) {
-				found = true
-			} else {
-				found = false
-			}
+			found = contains(openStackCluster.Spec.ControlPlaneAvailabilityZones, az.ZoneName)
 		}
-
+		// Add the AZ object to the failure domains for the cluster
 		openStackCluster.Status.FailureDomains[az.ZoneName] = clusterv1.FailureDomainSpec{
 			ControlPlane: found,
 		}