func()

in pkg/awsutils/awsutils.go [771:816]

• 41 lines of code
• 9 McCabe index (conditional complexity)

func (cache *EC2InstanceMetadataCache) awsGetFreeDeviceNumber() (int, error) {
	input := &ec2.DescribeInstancesInput{
		InstanceIds: []string{cache.instanceID},
	}

	start := time.Now()
	result, err := cache.ec2SVC.DescribeInstances(context.Background(), input)
	prometheusmetrics.Ec2ApiReq.WithLabelValues("DescribeInstances").Inc()
	prometheusmetrics.AwsAPILatency.WithLabelValues("DescribeInstances", fmt.Sprint(err != nil), awsReqStatus(err)).Observe(msSince(start))
	if err != nil {
		checkAPIErrorAndBroadcastEvent(err, "ec2:DescribeInstances")
		awsAPIErrInc("DescribeInstances", err)
		prometheusmetrics.Ec2ApiErr.WithLabelValues("DescribeInstances").Inc()
		log.Errorf("awsGetFreeDeviceNumber: Unable to retrieve instance data from EC2 control plane %v", err)
		return 0, errors.Wrap(err,
			"find a free device number for ENI: not able to retrieve instance data from EC2 control plane")
	}

	if len(result.Reservations) != 1 {
		return 0, errors.Errorf("awsGetFreeDeviceNumber: invalid instance id %s", cache.instanceID)
	}

	inst := result.Reservations[0].Instances[0]
	var device [maxENIs]bool
	for _, eni := range inst.NetworkInterfaces {
		// We don't support multi-card yet, so only account for network card zero
		if eni.Attachment != nil && aws.ToInt32(eni.Attachment.NetworkCardIndex) == 0 {
			if aws.ToInt32(eni.Attachment.DeviceIndex) > maxENIs {
				log.Warnf("The Device Index %d of the attached ENI %s > instance max slot %d",
					aws.ToInt32(eni.Attachment.DeviceIndex), aws.ToString(eni.NetworkInterfaceId),
					maxENIs)
			} else {
				log.Debugf("Discovered device number is used: %d", aws.ToInt32(eni.Attachment.DeviceIndex))
				device[aws.ToInt32(eni.Attachment.DeviceIndex)] = true
			}
		}
	}

	for freeDeviceIndex := 0; freeDeviceIndex < maxENIs; freeDeviceIndex++ {
		if !device[freeDeviceIndex] {
			log.Debugf("Found a free device number: %d", freeDeviceIndex)
			return freeDeviceIndex, nil
		}
	}
	return 0, errors.New("awsGetFreeDeviceNumber: no available device number")
}