@@ -43,7 +43,11 @@ func dockerStatsToContainerStats(dockerStats *types.StatsJSON) (*ContainerStats,
 	}, nil
 }
 
+// Safe return of storage stats based on Docker Stats (Unix)
 func getStorageStats(dockerStats *types.StatsJSON) (uint64, uint64) {
+	if dockerStats.BlkioStats.IoServiceBytesRecursive == nil {
+		seelog.Debug("storage stats (Unix) not reported for container")
+	}
 	// initialize block io and loop over stats to aggregate
 	storageReadBytes := uint64(0)
 	storageWriteBytes := uint64(0)
// +build !windows
// Copyright 2014-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"). You may
// not use this file except in compliance with the License. A copy of the
// License is located at
//
//	http://aws.amazon.com/apache2.0/
//
// or in the "license" file accompanying this file. This file is distributed
// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
// express or implied. See the License for the specific language governing
// permissions and limitations under the License.

package stats

import (
	"fmt"

	"github.com/cihub/seelog"
	"github.com/docker/docker/api/types"
)

// dockerStatsToContainerStats returns a new object of the ContainerStats object from docker stats.
func dockerStatsToContainerStats(dockerStats *types.StatsJSON) (*ContainerStats, error) {
	// The length of PercpuUsage represents the number of cores in an instance.
	if len(dockerStats.CPUStats.CPUUsage.PercpuUsage) == 0 || numCores == uint64(0) {
		seelog.Debug("Invalid container statistics reported, no cpu core usage reported")
		return nil, fmt.Errorf("Invalid container statistics reported, no cpu core usage reported")
	}

	cpuUsage := dockerStats.CPUStats.CPUUsage.TotalUsage / numCores
	memoryUsage := dockerStats.MemoryStats.Usage - dockerStats.MemoryStats.Stats["cache"]
	storageReadBytes, storageWriteBytes := getStorageStats(dockerStats)
	networkStats := getNetworkStats(dockerStats)
	return &ContainerStats{
		cpuUsage:          cpuUsage,
		memoryUsage:       memoryUsage,
		storageReadBytes:  storageReadBytes,
		storageWriteBytes: storageWriteBytes,
		networkStats:      networkStats,
		timestamp:         dockerStats.Read,
	}, nil
}

func getStorageStats(dockerStats *types.StatsJSON) (uint64, uint64) {
	// initialize block io and loop over stats to aggregate
	storageReadBytes := uint64(0)
	storageWriteBytes := uint64(0)
	for _, blockStat := range dockerStats.BlkioStats.IoServiceBytesRecursive {
		switch op := blockStat.Op; op {
		case "Read":
			storageReadBytes += blockStat.Value
		case "Write":
			storageWriteBytes += blockStat.Value
		default:
			//ignoring "Async", "Total", "Sum", etc
			continue
		}
	}
	return storageReadBytes, storageWriteBytes
}

should you return here? if there's no storage stats to report, why are we proceeding to the storage stats logic below?