kubernetes/kops · error

NatGateway %q has multiple addresses

Error message

NatGateway %q has multiple addresses

What it means

The NAT Gateway located via the route table exposes more than one NatGatewayAddress; kOps's ElasticIP model assumes one public IP per NAT Gateway, so the mapping is ambiguous and the find fails rather than guessing.

Source

Thrown at upup/pkg/fi/cloudup/awstasks/elastic_ip.go:87

func (e *ElasticIP) find(ctx context.Context, cloud awsup.AWSCloud) (*ElasticIP, error) {
	publicIP := e.PublicIP
	allocationID := e.ID

	// Find via RouteTable -> NatGateway -> ElasticIP
	if allocationID == nil && publicIP == nil && e.AssociatedNatGatewayRouteTable != nil {
		ngw, err := findNatGatewayFromRouteTable(ctx, cloud, e.AssociatedNatGatewayRouteTable)
		if err != nil {
			return nil, fmt.Errorf("error finding AssociatedNatGatewayRouteTable: %v", err)
		}

		if ngw == nil {
			klog.V(2).Infof("AssociatedNatGatewayRouteTable not found")
		} else {
			if len(ngw.NatGatewayAddresses) == 0 {
				return nil, fmt.Errorf("NatGateway %q has no addresses", *ngw.NatGatewayId)
			}
			if len(ngw.NatGatewayAddresses) > 1 {
				return nil, fmt.Errorf("NatGateway %q has multiple addresses", *ngw.NatGatewayId)
			}
			allocationID = ngw.NatGatewayAddresses[0].AllocationId
			if allocationID == nil {
				return nil, fmt.Errorf("NatGateway %q has nil addresses", *ngw.NatGatewayId)
			} else {
				klog.V(2).Infof("Found ElasticIP AllocationID %q via NatGateway", *allocationID)
			}
		}
	}

	// Find via tag on subnet
	// TODO: Deprecated, because doesn't round-trip with terraform
	if allocationID == nil && publicIP == nil && e.TagOnSubnet != nil && e.TagOnSubnet.ID != nil {
		var filters []ec2types.Filter
		filters = append(filters, awsup.NewEC2Filter("key", "AssociatedElasticIp"))
		filters = append(filters, awsup.NewEC2Filter("resource-id", *e.TagOnSubnet.ID))

		request := &ec2.DescribeTagsInput{

View on GitHub (pinned to 4c8573c808)

Solutions

1. Use a NAT Gateway with a single IP address, or reference the ElasticIP directly by allocationID/publicIP
2. Recreate the model without AssociatedNatGatewayRouteTable if multiple NAT IPs are required

When it happens

Trigger: Thrown at upup/pkg/fi/cloudup/awstasks/elastic_ip.go:87 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/c7be8313c40a76b1. Report an issue: GitHub.