feat: select the most available ip count subnet when launchInstance

Signed-off-by: Vacant2333 <vacant2333@gmail.com>

pkg/providers/instance/instance.go

@@ -341,17 +341,30 @@ func (p *DefaultProvider) getOverrides(instanceTypes []*cloudprovider.InstanceTy
 		if reqs.Compatible(offering.Requirements, scheduling.AllowUndefinedWellKnownLabels) != nil {
 			continue
 		}
-		subnet, ok := zonalSubnets[offering.Requirements.Get(corev1.LabelTopologyZone).Any()]
-		if !ok {
+
+		// Select the best subnet with the highest available IP count within the required zones.
+		var bestSubnet *subnet.Subnet
+		for _, zone := range offering.Requirements.Get(corev1.LabelTopologyZone).Values() {
+			if subnet, ok := zonalSubnets[zone]; !ok {
+				continue
+			} else if bestSubnet == nil || bestSubnet.AvailableIPAddressCount < subnet.AvailableIPAddressCount {
+				bestSubnet = subnet
+			}
+		}
+		if bestSubnet == nil {
 			continue
 		}
+
 		overrides = append(overrides, &ec2.FleetLaunchTemplateOverridesRequest{
 			InstanceType: aws.String(offering.parentInstanceTypeName),
-			SubnetId:     lo.ToPtr(subnet.ID),
+			SubnetId:     lo.ToPtr(bestSubnet.ID),
 			ImageId:      aws.String(image),
+			// Set Priority based on the available IP address count of the best subnet.
+			// This prioritization helps AWS choose subnets with higher IP availability first.
+			Priority: aws.Float64(float64(bestSubnet.AvailableIPAddressCount)),
 			// This is technically redundant, but is useful if we have to parse insufficient capacity errors from
 			// CreateFleet so that we can figure out the zone rather than additional API calls to look up the subnet
-			AvailabilityZone: lo.ToPtr(subnet.Zone),
+			AvailabilityZone: lo.ToPtr(bestSubnet.Zone),
 		})
 	}
 	return overrides

pkg/providers/subnet/subnet.go

@@ -166,6 +166,13 @@ func (p *DefaultProvider) ZonalSubnetsForLaunch(ctx context.Context, nodeClass *
 		if trackedIPs, ok := p.inflightIPs[subnet.ID]; ok {
 			prevIPs = trackedIPs
 		}
+
+		// Check if the remaining IP count is insufficient to meet the predicted IP usage;
+		// if so, remove this subnet zone record from inflightIPs and continue to the next item in the loop。
+		if prevIPs-predictedIPsUsed < 0 {
+			delete(zonalSubnets, subnet.Zone)
+			continue
+		}
 		p.inflightIPs[subnet.ID] = prevIPs - predictedIPsUsed
 	}
 	return zonalSubnets, nil