func describeInstanceTypes()

in scripts/gen_vpc_ip_limits.go [133:196]
49 lines of code
12 McCabe index (conditional complexity)

func describeInstanceTypes(ctx context.Context, cfg aws.Config, region string, eniLimitMap map[string]vpc.InstanceTypeLimits) {
	log.Infof("Describing instance types in region=%s", region)

	cfg.Region = region
	client := ec2.NewFromConfig(cfg)

	paginator := ec2.NewDescribeInstanceTypesPaginator(client, &ec2.DescribeInstanceTypesInput{})

	// Iterate through all pages
	for paginator.HasMorePages() {
		output, err := paginator.NextPage(ctx)
		if err != nil {
			log.Fatalf("Failed to call EC2 DescribeInstanceTypes: %v", err)
		}

		// We just want the type name, ENI and IP limits
		for _, info := range output.InstanceTypes {
			// Ignore any missing values
			instanceType := string(info.InstanceType)

			// only one network card is supported, so use the MaximumNetworkInterfaces from the default card if more than one are present
			var eniLimit int
			if len(info.NetworkInfo.NetworkCards) > 1 {
				eniLimit = int(*info.NetworkInfo.NetworkCards[*info.NetworkInfo.DefaultNetworkCardIndex].MaximumNetworkInterfaces)
			} else {
				eniLimit = int(*info.NetworkInfo.MaximumNetworkInterfaces)
			}

			ipv4Limit := int(*info.NetworkInfo.Ipv4AddressesPerInterface)
			isBareMetalInstance := *info.BareMetal
			hypervisorType := string(info.Hypervisor)
			if hypervisorType == "" {
				hypervisorType = "unknown"
			}

			networkCards := make([]vpc.NetworkCard, *info.NetworkInfo.MaximumNetworkCards)
			defaultNetworkCardIndex := int(*info.NetworkInfo.DefaultNetworkCardIndex)

			for idx := 0; idx < len(networkCards); idx++ {
				networkCards[idx] = vpc.NetworkCard{
					MaximumNetworkInterfaces: int64(*info.NetworkInfo.NetworkCards[idx].MaximumNetworkInterfaces),
					NetworkCardIndex:         int64(*info.NetworkInfo.NetworkCards[idx].NetworkCardIndex),
				}
			}

			if instanceType != "" && eniLimit > 0 && ipv4Limit > 0 {
				limits := vpc.InstanceTypeLimits{
					ENILimit:                eniLimit,
					IPv4Limit:               ipv4Limit,
					NetworkCards:            networkCards,
					HypervisorType:          strconv.Quote(hypervisorType),
					IsBareMetal:             isBareMetalInstance,
					DefaultNetworkCardIndex: defaultNetworkCardIndex,
				}

				if existingLimits, contains := eniLimitMap[instanceType]; contains && !reflect.DeepEqual(existingLimits, limits) {
					// this should never happen
					log.Fatalf("A previous region has different limits for instanceType=%s than region=%s", instanceType, region)
				}
				eniLimitMap[instanceType] = limits
			}
		}
	}
}