Support StatisticValues in cloudwatch output plugin (#4364)

plugins/outputs/cloudwatch/README.md

@@ -36,3 +36,13 @@ Examples include but are not limited to:
 ### namespace
 
 The namespace used for AWS CloudWatch metrics.
+
+### write_statistics
+
+If you have a large amount of metrics, you should consider to send statistic 
+values instead of raw metrics which could not only improve performance but 
+also save AWS API cost. If enable this flag, this plugin would parse the required 
+[CloudWatch statistic fields](https://docs.aws.amazon.com/sdk-for-go/api/service/cloudwatch/#StatisticSet) 
+(count, min, max, and sum) and send them to CloudWatch. You could use `basicstats` 
+aggregator to calculate those fields. If not all statistic fields are available, 
+all fields would still be sent as raw metrics.

plugins/outputs/cloudwatch/cloudwatch.go

@@ -28,6 +28,128 @@ type CloudWatch struct {
 
 	Namespace string `toml:"namespace"` // CloudWatch Metrics Namespace
 	svc       *cloudwatch.CloudWatch
+
+	WriteStatistics bool `toml:"write_statistics"`
+}
+
+type statisticType int
+
+const (
+	statisticTypeNone statisticType = iota
+	statisticTypeMax
+	statisticTypeMin
+	statisticTypeSum
+	statisticTypeCount
+)
+
+type cloudwatchField interface {
+	addValue(sType statisticType, value float64)
+	buildDatum() []*cloudwatch.MetricDatum
+}
+
+type statisticField struct {
+	metricName string
+	fieldName  string
+	tags       map[string]string
+	values     map[statisticType]float64
+	timestamp  time.Time
+}
+
+func (f *statisticField) addValue(sType statisticType, value float64) {
+	if sType != statisticTypeNone {
+		f.values[sType] = value
+	}
+}
+
+func (f *statisticField) buildDatum() []*cloudwatch.MetricDatum {
+
+	var datums []*cloudwatch.MetricDatum
+
+	if f.hasAllFields() {
+		// If we have all required fields, we build datum with StatisticValues
+		min, _ := f.values[statisticTypeMin]
+		max, _ := f.values[statisticTypeMax]
+		sum, _ := f.values[statisticTypeSum]
+		count, _ := f.values[statisticTypeCount]
+
+		datum := &cloudwatch.MetricDatum{
+			MetricName: aws.String(strings.Join([]string{f.metricName, f.fieldName}, "_")),
+			Dimensions: BuildDimensions(f.tags),
+			Timestamp:  aws.Time(f.timestamp),
+			StatisticValues: &cloudwatch.StatisticSet{
+				Minimum:     aws.Float64(min),
+				Maximum:     aws.Float64(max),
+				Sum:         aws.Float64(sum),
+				SampleCount: aws.Float64(count),
+			},
+		}
+
+		datums = append(datums, datum)
+
+	} else {
+		// If we don't have all required fields, we build each field as independent datum
+		for sType, value := range f.values {
+			datum := &cloudwatch.MetricDatum{
+				Value:      aws.Float64(value),
+				Dimensions: BuildDimensions(f.tags),
+				Timestamp:  aws.Time(f.timestamp),
+			}
+
+			switch sType {
+			case statisticTypeMin:
+				datum.MetricName = aws.String(strings.Join([]string{f.metricName, f.fieldName, "min"}, "_"))
+			case statisticTypeMax:
+				datum.MetricName = aws.String(strings.Join([]string{f.metricName, f.fieldName, "max"}, "_"))
+			case statisticTypeSum:
+				datum.MetricName = aws.String(strings.Join([]string{f.metricName, f.fieldName, "sum"}, "_"))
+			case statisticTypeCount:
+				datum.MetricName = aws.String(strings.Join([]string{f.metricName, f.fieldName, "count"}, "_"))
+			default:
+				// should not be here
+				continue
+			}
+
+			datums = append(datums, datum)
+		}
+	}
+
+	return datums
+}
+
+func (f *statisticField) hasAllFields() bool {
+
+	_, hasMin := f.values[statisticTypeMin]
+	_, hasMax := f.values[statisticTypeMax]
+	_, hasSum := f.values[statisticTypeSum]
+	_, hasCount := f.values[statisticTypeCount]
+
+	return hasMin && hasMax && hasSum && hasCount
+}
+
+type valueField struct {
+	metricName string
+	fieldName  string
+	tags       map[string]string
+	value      float64
+	timestamp  time.Time
+}
+
+func (f *valueField) addValue(sType statisticType, value float64) {
+	if sType == statisticTypeNone {
+		f.value = value
+	}
+}
+
+func (f *valueField) buildDatum() []*cloudwatch.MetricDatum {
+
+	return []*cloudwatch.MetricDatum{
+		{
+			MetricName: aws.String(strings.Join([]string{f.metricName, f.fieldName}, "_")),
+			Value:      aws.Float64(f.value),
+			Dimensions: BuildDimensions(f.tags),
+			Timestamp:  aws.Time(f.timestamp),
+		},
+	}
 }
 
 var sampleConfig = `
@@ -57,6 +179,14 @@ var sampleConfig = `
 
   ## Namespace for the CloudWatch MetricDatums
   namespace = "InfluxData/Telegraf"
+
+  ## If you have a large amount of metrics, you should consider to send statistic 
+  ## values instead of raw metrics which could not only improve performance but 
+  ## also save AWS API cost. If enable this flag, this plugin would parse the required 
+  ## CloudWatch statistic fields (count, min, max, and sum) and send them to CloudWatch. 
+  ## You could use basicstats aggregator to calculate those fields. If not all statistic 
+  ## fields are available, all fields would still be sent as raw metrics. 
+  # write_statistics = false
 `
 
 func (c *CloudWatch) SampleConfig() string {
@@ -104,7 +234,7 @@ func (c *CloudWatch) Write(metrics []telegraf.Metric) error {
 
 	var datums []*cloudwatch.MetricDatum
 	for _, m := range metrics {
-		d := BuildMetricDatum(m)
+		d := BuildMetricDatum(c.WriteStatistics, m)
 		datums = append(datums, d...)
 	}
 
@@ -159,67 +289,58 @@ func PartitionDatums(size int, datums []*cloudwatch.MetricDatum) [][]*cloudwatch
 	return partitions
 }
 
-// Make a MetricDatum for each field in a Point. Only fields with values that can be
-// converted to float64 are supported. Non-supported fields are skipped.
-func BuildMetricDatum(point telegraf.Metric) []*cloudwatch.MetricDatum {
-	datums := make([]*cloudwatch.MetricDatum, len(point.Fields()))
-	i := 0
+// Make a MetricDatum from telegraf.Metric. It would check if all required fields of
+// cloudwatch.StatisticSet are available. If so, it would build MetricDatum from statistic values.
+// Otherwise, fields would still been built independently.
+func BuildMetricDatum(buildStatistic bool, point telegraf.Metric) []*cloudwatch.MetricDatum {
 
-	var value float64
+	fields := make(map[string]cloudwatchField)
 
 	for k, v := range point.Fields() {
-		switch t := v.(type) {
-		case int:
-			value = float64(t)
-		case int32:
-			value = float64(t)
-		case int64:
-			value = float64(t)
-		case uint64:
-			value = float64(t)
-		case float64:
-			value = t
-		case bool:
-			if t {
-				value = 1
-			} else {
-				value = 0
-			}
-		case time.Time:
-			value = float64(t.Unix())
-		default:
-			// Skip unsupported type.
-			datums = datums[:len(datums)-1]
-			continue
-		}
 
-		// Do CloudWatch boundary checking
-		// Constraints at: http://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_MetricDatum.html
-		if math.IsNaN(value) {
-			datums = datums[:len(datums)-1]
-			continue
-		}
-		if math.IsInf(value, 0) {
-			datums = datums[:len(datums)-1]
+		val, ok := convert(v)
+		if !ok {
+			// Only fields with values that can be converted to float64 (and within CloudWatch boundary) are supported.
+			// Non-supported fields are skipped.
 			continue
 		}
-		if value > 0 && value < float64(8.515920e-109) {
-			datums = datums[:len(datums)-1]
-			continue
-		}
-		if value > float64(1.174271e+108) {
-			datums = datums[:len(datums)-1]
+
+		sType, fieldName := getStatisticType(k)
+
+		// If statistic metric is not enabled or non-statistic type, just take current field as a value field.
+		if !buildStatistic || sType == statisticTypeNone {
+			fields[k] = &valueField{
+				metricName: point.Name(),
+				fieldName:  k,
+				tags:       point.Tags(),
+				timestamp:  point.Time(),
+				value:      val,
+			}
 			continue
 		}
 
-		datums[i] = &cloudwatch.MetricDatum{
-			MetricName: aws.String(strings.Join([]string{point.Name(), k}, "_")),
-			Value:      aws.Float64(value),
-			Dimensions: BuildDimensions(point.Tags()),
-			Timestamp:  aws.Time(point.Time()),
+		// Otherwise, it shall be a statistic field.
+		if _, ok := fields[fieldName]; !ok {
+			// Hit an uncached field, create statisticField for first time
+			fields[fieldName] = &statisticField{
+				metricName: point.Name(),
+				fieldName:  fieldName,
+				tags:       point.Tags(),
+				timestamp:  point.Time(),
+				values: map[statisticType]float64{
+					sType: val,
+				},
+			}
+		} else {
+			// Add new statistic value to this field
+			fields[fieldName].addValue(sType, val)
 		}
+	}
 
-		i += 1
+	var datums []*cloudwatch.MetricDatum
+	for _, f := range fields {
+		d := f.buildDatum()
+		datums = append(datums, d...)
 	}
 
 	return datums
@@ -268,6 +389,72 @@ func BuildDimensions(mTags map[string]string) []*cloudwatch.Dimension {
 	return dimensions
 }
 
+func getStatisticType(name string) (sType statisticType, fieldName string) {
+	switch {
+	case strings.HasSuffix(name, "_max"):
+		sType = statisticTypeMax
+		fieldName = strings.TrimSuffix(name, "_max")
+	case strings.HasSuffix(name, "_min"):
+		sType = statisticTypeMin
+		fieldName = strings.TrimSuffix(name, "_min")
+	case strings.HasSuffix(name, "_sum"):
+		sType = statisticTypeSum
+		fieldName = strings.TrimSuffix(name, "_sum")
+	case strings.HasSuffix(name, "_count"):
+		sType = statisticTypeCount
+		fieldName = strings.TrimSuffix(name, "_count")
+	default:
+		sType = statisticTypeNone
+		fieldName = name
+	}
+	return
+}
+
+func convert(v interface{}) (value float64, ok bool) {
+
+	ok = true
+
+	switch t := v.(type) {
+	case int:
+		value = float64(t)
+	case int32:
+		value = float64(t)
+	case int64:
+		value = float64(t)
+	case uint64:
+		value = float64(t)
+	case float64:
+		value = t
+	case bool:
+		if t {
+			value = 1
+		} else {
+			value = 0
+		}
+	case time.Time:
+		value = float64(t.Unix())
+	default:
+		// Skip unsupported type.
+		ok = false
+		return
+	}
+
+	// Do CloudWatch boundary checking
+	// Constraints at: http://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_MetricDatum.html
+	switch {
+	case math.IsNaN(value):
+		return 0, false
+	case math.IsInf(value, 0):
+		return 0, false
+	case value > 0 && value < float64(8.515920e-109):
+		return 0, false
+	case value > float64(1.174271e+108):
+		return 0, false
+	}
+
+	return
+}
+
 func init() {
 	outputs.Add("cloudwatch", func() telegraf.Output {
 		return &CloudWatch{}