OCPBUGS-54979: sort zone slices extracted from map of byo subnets

Previously, since zones are extracted from map keys, order is not guaranteed.
This can lead to an issue where master CAPI machine manifest is configured
with a different subnet ID than MAPI machine manifest as they are
handled separately.

This commit ensures the zones are sorted by lexical order before
processing CAPI/MAP machine manifests so that zones are distributed in
the same order.

Author: tthvo

pkg/asset/machines/clusterapi.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net"
 	"path/filepath"
+	"slices"
 	"strings"
 	"time"
 
@@ -125,6 +126,10 @@ func (c *ClusterAPI) Generate(ctx context.Context, dependencies asset.Parents) e
 				for zone := range subnets {
 					mpool.Zones = append(mpool.Zones, zone)
 				}
+				// Since zones are extracted from map keys, order is not guaranteed.
+				// Thus, sort the zones by lexical order to ensure CAPI and MAPI machines
+				// are distributed to zones in the same order.
+				slices.Sort(mpool.Zones)
 			} else {
 				mpool.Zones, err = installConfig.AWS.AvailabilityZones(ctx)
 				if err != nil {

pkg/asset/machines/master.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 
 	baremetalhost "github.com/metal3-io/baremetal-operator/apis/metal3.io/v1alpha1"
@@ -196,6 +197,10 @@ func (m *Master) Generate(ctx context.Context, dependencies asset.Parents) error
 				for zone := range subnets {
 					mpool.Zones = append(mpool.Zones, zone)
 				}
+				// Since zones are extracted from map keys, order is not guaranteed.
+				// Thus, sort the zones by lexical order to ensure CAPI and MAPI machines
+				// are distributed to zones in the same order.
+				slices.Sort(mpool.Zones)
 			} else {
 				mpool.Zones, err = installConfig.AWS.AvailabilityZones(ctx)
 				if err != nil {