func()

in pkg/providers/v1/aws.go [3693:3784]

• 74 lines of code
• 18 McCabe index (conditional complexity)

func (c *Cloud) findELBSubnets(internalELB bool) ([]string, error) {
	vpcIDFilter := newEc2Filter("vpc-id", c.vpcID)

	subnets, err := c.findSubnets()
	if err != nil {
		return nil, err
	}

	rRequest := &ec2.DescribeRouteTablesInput{}
	rRequest.Filters = []*ec2.Filter{vpcIDFilter}
	rt, err := c.ec2.DescribeRouteTables(rRequest)
	if err != nil {
		return nil, fmt.Errorf("error describe route table: %q", err)
	}

	subnetsByAZ := make(map[string]*ec2.Subnet)
	for _, subnet := range subnets {
		az := aws.StringValue(subnet.AvailabilityZone)
		id := aws.StringValue(subnet.SubnetId)
		if az == "" || id == "" {
			klog.Warningf("Ignoring subnet with empty az/id: %v", subnet)
			continue
		}

		isPublic, err := isSubnetPublic(rt, id)
		if err != nil {
			return nil, err
		}
		if !internalELB && !isPublic {
			klog.V(2).Infof("Ignoring private subnet for public ELB %q", id)
			continue
		}

		existing := subnetsByAZ[az]
		if existing == nil {
			subnetsByAZ[az] = subnet
			continue
		}

		// Try to break the tie using the role tag
		var tagName string
		if internalELB {
			tagName = TagNameSubnetInternalELB
		} else {
			tagName = TagNameSubnetPublicELB
		}

		_, existingHasTag := findTag(existing.Tags, tagName)
		_, subnetHasTag := findTag(subnet.Tags, tagName)

		if existingHasTag != subnetHasTag {
			if subnetHasTag {
				subnetsByAZ[az] = subnet
			}
			continue
		}

		// Prefer the one with the cluster Tag
		existingHasClusterTag := c.tagging.hasClusterTag(existing.Tags)
		subnetHasClusterTag := c.tagging.hasClusterTag(subnet.Tags)
		if existingHasClusterTag != subnetHasClusterTag {
			if subnetHasClusterTag {
				subnetsByAZ[az] = subnet
			}
			continue
		}

		// If we have two subnets for the same AZ we arbitrarily choose the one that is first lexicographically.
		if strings.Compare(*existing.SubnetId, *subnet.SubnetId) > 0 {
			klog.Warningf("Found multiple subnets in AZ %q; choosing %q between subnets %q and %q", az, *subnet.SubnetId, *existing.SubnetId, *subnet.SubnetId)
			subnetsByAZ[az] = subnet
			continue
		}

		klog.Warningf("Found multiple subnets in AZ %q; choosing %q between subnets %q and %q", az, *existing.SubnetId, *existing.SubnetId, *subnet.SubnetId)
		continue
	}

	var azNames []string
	for key := range subnetsByAZ {
		azNames = append(azNames, key)
	}

	sort.Strings(azNames)

	var subnetIDs []string
	for _, key := range azNames {
		subnetIDs = append(subnetIDs, aws.StringValue(subnetsByAZ[key].SubnetId))
	}

	return subnetIDs, nil
}