Cherry-pick #8126 to 6.x: Add docker diskio stats on Windows

CHANGELOG.asciidoc

@@ -56,6 +56,7 @@ https://github.com/elastic/beats/compare/v6.4.0...6.x[Check the HEAD diff]
 
 - Fix golang.heap.gc.cpu_fraction type from long to float in Golang module. {pull}7789[7789]
 - Fixed the RPM by designating the modules.d config files as configuration data in the RPM spec. {issue}8075[8075]
+- Add docker diskio stats on Windows. {issue}6815[6815] {pull}8126[8126]
 
 *Packetbeat*
 

metricbeat/module/docker/diskio/diskio_test.go

@@ -222,7 +222,7 @@ func setTime(index int) {
 	newBlkioRaw[index].Time = oldBlkioRaw[index].Time.Add(time.Duration(2000000000))
 }
 
-func TestGetBlkioStats(t *testing.T) {
+func TestGetBlkioStatsList(t *testing.T) {
 	start := time.Now()
 	later := start.Add(10 * time.Second)
 
@@ -232,7 +232,7 @@ func TestGetBlkioStats(t *testing.T) {
 		},
 	}
 
-	dockerStats := &docker.Stat{
+	dockerStats := []docker.Stat{{
 		Container: &types.Container{
 			ID:    "cebada",
 			Names: []string{"test"},
@@ -258,9 +258,49 @@ func TestGetBlkioStats(t *testing.T) {
 				},
 			},
 		}},
+	}}
+
+	statsList := blkioService.getBlkioStatsList(dockerStats, true)
+	stats := statsList[0]
+	assert.Equal(t, float64(5), stats.reads)
+	assert.Equal(t, float64(10), stats.writes)
+	assert.Equal(t, float64(15), stats.totals)
+	assert.Equal(t,
+		BlkioRaw{Time: later, reads: 150, writes: 300, totals: 450},
+		stats.serviced)
+	assert.Equal(t,
+		BlkioRaw{Time: later, reads: 1500, writes: 3000, totals: 4500},
+		stats.servicedBytes)
+}
+
+func TestGetBlkioStatsListWindows(t *testing.T) {
+	start := time.Now()
+	later := start.Add(10 * time.Second)
+
+	blkioService := BlkioService{
+		map[string]BlkioRaw{
+			"cebada": {Time: start, reads: 100, writes: 200, totals: 300},
+		},
 	}
 
-	stats := blkioService.getBlkioStats(dockerStats, true)
+	dockerStats := []docker.Stat{{
+		Container: &types.Container{
+			ID:    "cebada",
+			Names: []string{"test"},
+		},
+		Stats: types.StatsJSON{Stats: types.Stats{
+			Read: later,
+			StorageStats: types.StorageStats{
+				ReadCountNormalized:  150,
+				WriteCountNormalized: 300,
+				ReadSizeBytes:        1500,
+				WriteSizeBytes:       3000,
+			},
+		}},
+	}}
+
+	statsList := blkioService.getBlkioStatsList(dockerStats, true)
+	stats := statsList[0]
 	assert.Equal(t, float64(5), stats.reads)
 	assert.Equal(t, float64(10), stats.writes)
 	assert.Equal(t, float64(15), stats.totals)

metricbeat/module/docker/diskio/helper.go

@@ -36,13 +36,30 @@ type BlkioStats struct {
 	servicedBytes BlkioRaw
 }
 
+// Add adds blkio stats
+func (s *BlkioStats) Add(o *BlkioStats) {
+	s.reads += o.reads
+	s.writes += o.writes
+	s.totals += o.totals
+
+	s.serviced.Add(&o.serviced)
+	s.servicedBytes.Add(&o.servicedBytes)
+}
+
 type BlkioRaw struct {
 	Time   time.Time
 	reads  uint64
 	writes uint64
 	totals uint64
 }
 
+// Add adds blkio raw stats
+func (s *BlkioRaw) Add(o *BlkioRaw) {
+	s.reads += o.reads
+	s.writes += o.writes
+	s.totals += o.totals
+}
+
 // BlkioService is a helper to collect and calculate disk I/O metrics
 type BlkioService struct {
 	lastStatsPerContainer map[string]BlkioRaw
@@ -61,34 +78,59 @@ func (io *BlkioService) getBlkioStatsList(rawStats []docker.Stat, dedot bool) []
 	statsPerContainer := make(map[string]BlkioRaw)
 	for _, myRawStats := range rawStats {
 		stats := io.getBlkioStats(&myRawStats, dedot)
-		statsPerContainer[myRawStats.Container.ID] = stats.serviced
+		storageStats := io.getStorageStats(&myRawStats, dedot)
+		stats.Add(&storageStats)
+
+		oldStats, exist := io.lastStatsPerContainer[stats.Container.ID]
+		if exist {
+			stats.reads = io.getReadPs(&oldStats, &stats.serviced)
+			stats.writes = io.getWritePs(&oldStats, &stats.serviced)
+			stats.totals = io.getTotalPs(&oldStats, &stats.serviced)
+		}
+
+		statsPerContainer[stats.Container.ID] = stats.serviced
 		formattedStats = append(formattedStats, stats)
 	}
 
 	io.lastStatsPerContainer = statsPerContainer
 	return formattedStats
 }
 
-func (io *BlkioService) getBlkioStats(myRawStat *docker.Stat, dedot bool) BlkioStats {
-	newBlkioStats := io.getNewStats(myRawStat.Stats.Read, myRawStat.Stats.BlkioStats.IoServicedRecursive)
-	bytesBlkioStats := io.getNewStats(myRawStat.Stats.Read, myRawStat.Stats.BlkioStats.IoServiceBytesRecursive)
+// getStorageStats collects diskio metrics from StorageStats structure, that
+// is populated in Windows systems only
+func (io *BlkioService) getStorageStats(myRawStats *docker.Stat, dedot bool) BlkioStats {
+	return BlkioStats{
+		Time:      myRawStats.Stats.Read,
+		Container: docker.NewContainer(myRawStats.Container, dedot),
+
+		serviced: BlkioRaw{
+			reads:  myRawStats.Stats.StorageStats.ReadCountNormalized,
+			writes: myRawStats.Stats.StorageStats.WriteCountNormalized,
+			totals: myRawStats.Stats.StorageStats.ReadCountNormalized + myRawStats.Stats.StorageStats.WriteCountNormalized,
+		},
+
+		servicedBytes: BlkioRaw{
+			reads:  myRawStats.Stats.StorageStats.ReadSizeBytes,
+			writes: myRawStats.Stats.StorageStats.WriteSizeBytes,
+			totals: myRawStats.Stats.StorageStats.ReadSizeBytes + myRawStats.Stats.StorageStats.WriteSizeBytes,
+		},
+	}
+}
 
-	myBlkioStats := BlkioStats{
+// getBlkioStats collects diskio metrics from BlkioStats structures, that
+// are not populated in Windows
+func (io *BlkioService) getBlkioStats(myRawStat *docker.Stat, dedot bool) BlkioStats {
+	return BlkioStats{
 		Time:      myRawStat.Stats.Read,
 		Container: docker.NewContainer(myRawStat.Container, dedot),
 
-		serviced:      newBlkioStats,
-		servicedBytes: bytesBlkioStats,
+		serviced: io.getNewStats(
+			myRawStat.Stats.Read,
+			myRawStat.Stats.BlkioStats.IoServicedRecursive),
+		servicedBytes: io.getNewStats(
+			myRawStat.Stats.Read,
+			myRawStat.Stats.BlkioStats.IoServiceBytesRecursive),
 	}
-
-	oldBlkioStats, exist := io.lastStatsPerContainer[myRawStat.Container.ID]
-	if exist {
-		myBlkioStats.reads = io.getReadPs(&oldBlkioStats, &newBlkioStats)
-		myBlkioStats.writes = io.getWritePs(&oldBlkioStats, &newBlkioStats)
-		myBlkioStats.totals = io.getTotalPs(&oldBlkioStats, &newBlkioStats)
-	}
-
-	return myBlkioStats
 }
 
 func (io *BlkioService) getNewStats(time time.Time, blkioEntry []types.BlkioStatEntry) BlkioRaw {