feat(aggregators.basicstats): Add first field (#15948)

plugins/aggregators/basicstats/README.md

@@ -1,8 +1,8 @@
 # BasicStats Aggregator Plugin
 
 The BasicStats aggregator plugin gives count, diff, max, min, mean,
-non_negative_diff, sum, s2(variance), stdev for a set of values, emitting the
+non_negative_diff, sum, s2(variance), stdev for a set of values, last and
-aggregate every `period` seconds.
+first, emitting the aggregate every `period` seconds.
 
 ## Global configuration options <!-- @/docs/includes/plugin_config.md -->
 
@@ -26,7 +26,7 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   # drop_original = false
 
   ## Configures which basic stats to push as fields
-  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","percent_change","stdev","s2","sum","interval","last"]
+  # stats = ["count","min","max","mean","variance","stdev"]
 ```
 
 - stats
@@ -52,6 +52,7 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   - field1_stdev (standard deviation)
   - field1_interval (interval in nanoseconds)
   - field1_last (last aggregated value)
+  - field1_first (first aggregated value)
 
 ## Tags
 
@@ -65,5 +66,5 @@ system,host=tars load1=1 1475583990000000000
 system,host=tars load1_count=2,load1_diff=0,load1_rate=0,load1_max=1,load1_min=1,load1_mean=1,load1_sum=2,load1_s2=0,load1_stdev=0,load1_interval=10000000000i,load1_last=1 1475584010000000000
 system,host=tars load1=1 1475584020000000000
 system,host=tars load1=3 1475584030000000000
-system,host=tars load1_count=2,load1_diff=2,load1_rate=0.2,load1_max=3,load1_min=1,load1_mean=2,load1_sum=4,load1_s2=2,load1_stdev=1.414162,load1_interval=10000000000i,load1_last=3 1475584010000000000
+system,host=tars load1_count=2,load1_diff=2,load1_rate=0.2,load1_max=3,load1_min=1,load1_mean=2,load1_sum=4,load1_s2=2,load1_stdev=1.414162,load1_interval=10000000000i,load1_last=3,load1_first=3 1475584010000000000
 ```

plugins/aggregators/basicstats/basicstats.go

@@ -36,6 +36,7 @@ type configuredStats struct {
 	percentChange   bool
 	interval        bool
 	last            bool
+	first           bool
 }
 
 func NewBasicStats() *BasicStats {
@@ -60,6 +61,7 @@ type basicstats struct {
 	rate     float64
 	interval time.Duration
 	last     float64
+	first    float64
 	M2       float64   // intermediate value for variance/stdev
 	PREVIOUS float64   // intermediate value for diff
 	TIME     time.Time // intermediate value for rate
@@ -89,6 +91,7 @@ func (b *BasicStats) Add(in telegraf.Metric) {
 					diff:     0.0,
 					rate:     0.0,
 					last:     fv,
+					first:    fv,
 					M2:       0.0,
 					PREVIOUS: fv,
 					TIME:     in.Time(),
@@ -111,6 +114,7 @@ func (b *BasicStats) Add(in telegraf.Metric) {
 						rate:     0.0,
 						interval: 0,
 						last:     fv,
+						first:    fv,
 						M2:       0.0,
 						PREVIOUS: fv,
 						TIME:     in.Time(),
@@ -181,6 +185,9 @@ func (b *BasicStats) Push(acc telegraf.Accumulator) {
 			if b.statsConfig.last {
 				fields[k+"_last"] = v.last
 			}
+			if b.statsConfig.first {
+				fields[k+"_first"] = v.first
+			}
 
 			// v.count always >=1
 			if v.count > 1 {
@@ -254,6 +261,8 @@ func (b *BasicStats) parseStats() *configuredStats {
 			parsed.interval = true
 		case "last":
 			parsed.last = true
+		case "first":
+			parsed.first = true
 		default:
 			b.Log.Warnf("Unrecognized basic stat %q, ignoring", name)
 		}
@@ -279,6 +288,7 @@ func (b *BasicStats) initConfiguredStats() {
 			percentChange:   false,
 			interval:        false,
 			last:            false,
+			first:           false,
 		}
 	} else {
 		b.statsConfig = b.parseStats()

plugins/aggregators/basicstats/basicstats_test.go

@@ -111,7 +111,7 @@ func TestBasicStatsWithPeriod(t *testing.T) {
 func TestBasicStatsDifferentPeriods(t *testing.T) {
 	acc := testutil.Accumulator{}
 	minmax := NewBasicStats()
-	minmax.Stats = []string{"count", "max", "min", "mean", "last"}
+	minmax.Stats = []string{"count", "max", "min", "mean", "last", "first"}
 	minmax.Log = testutil.Logger{}
 	minmax.initConfiguredStats()
 
@@ -123,26 +123,31 @@ func TestBasicStatsDifferentPeriods(t *testing.T) {
 		"a_min":   float64(1),
 		"a_mean":  float64(1),
 		"a_last":  float64(1),
+		"a_first": float64(1),
 		"b_count": float64(1), // b
 		"b_max":   float64(1),
 		"b_min":   float64(1),
 		"b_mean":  float64(1),
 		"b_last":  float64(1),
+		"b_first": float64(1),
 		"c_count": float64(1), // c
 		"c_max":   float64(2),
 		"c_min":   float64(2),
 		"c_mean":  float64(2),
 		"c_last":  float64(2),
+		"c_first": float64(2),
 		"d_count": float64(1), // d
 		"d_max":   float64(2),
 		"d_min":   float64(2),
 		"d_mean":  float64(2),
 		"d_last":  float64(2),
+		"d_first": float64(2),
 		"g_count": float64(1), // g
 		"g_max":   float64(3),
 		"g_min":   float64(3),
 		"g_mean":  float64(3),
 		"g_last":  float64(3),
+		"g_first": float64(3),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -159,36 +164,43 @@ func TestBasicStatsDifferentPeriods(t *testing.T) {
 		"a_min":   float64(1),
 		"a_mean":  float64(1),
 		"a_last":  float64(1),
+		"a_first": float64(1),
 		"b_count": float64(1), // b
 		"b_max":   float64(3),
 		"b_min":   float64(3),
 		"b_mean":  float64(3),
 		"b_last":  float64(3),
+		"b_first": float64(3),
 		"c_count": float64(1), // c
 		"c_max":   float64(4),
 		"c_min":   float64(4),
 		"c_mean":  float64(4),
 		"c_last":  float64(4),
+		"c_first": float64(4),
 		"d_count": float64(1), // d
 		"d_max":   float64(6),
 		"d_min":   float64(6),
 		"d_mean":  float64(6),
 		"d_last":  float64(6),
+		"d_first": float64(6),
 		"e_count": float64(1), // e
 		"e_max":   float64(200),
 		"e_min":   float64(200),
 		"e_mean":  float64(200),
 		"e_last":  float64(200),
+		"e_first": float64(200),
 		"f_count": float64(1), // f
 		"f_max":   float64(200),
 		"f_min":   float64(200),
 		"f_mean":  float64(200),
 		"f_last":  float64(200),
+		"f_first": float64(200),
 		"g_count": float64(1), // g
 		"g_max":   float64(1),
 		"g_min":   float64(1),
 		"g_mean":  float64(1),
 		"g_last":  float64(1),
+		"g_first": float64(1),
 	}
 	expectedTags = map[string]string{
 		"foo": "bar",
@@ -629,7 +641,7 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 	acc := testutil.Accumulator{}
 	minmax := NewBasicStats()
 	minmax.Log = testutil.Logger{}
-	minmax.Stats = []string{"count", "min", "max", "mean", "stdev", "s2", "sum", "last"}
+	minmax.Stats = []string{"count", "min", "max", "mean", "stdev", "s2", "sum", "last", "first"}
 	minmax.initConfiguredStats()
 
 	minmax.Add(m1)
@@ -645,6 +657,7 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"a_s2":    float64(0),
 		"a_sum":   float64(2),
 		"a_last":  float64(1),
+		"a_first": float64(1),
 		"b_count": float64(2), // b
 		"b_max":   float64(3),
 		"b_min":   float64(1),
@@ -653,6 +666,7 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"b_sum":   float64(4),
 		"b_last":  float64(3),
 		"b_stdev": math.Sqrt(2),
+		"b_first": float64(1),
 		"c_count": float64(2), // c
 		"c_max":   float64(4),
 		"c_min":   float64(2),
@@ -661,6 +675,7 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"c_stdev": math.Sqrt(2),
 		"c_sum":   float64(6),
 		"c_last":  float64(4),
+		"c_first": float64(2),
 		"d_count": float64(2), // d
 		"d_max":   float64(6),
 		"d_min":   float64(2),
@@ -669,18 +684,21 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"d_stdev": math.Sqrt(8),
 		"d_sum":   float64(8),
 		"d_last":  float64(6),
+		"d_first": float64(2),
 		"e_count": float64(1), // e
 		"e_max":   float64(200),
 		"e_min":   float64(200),
 		"e_mean":  float64(200),
 		"e_sum":   float64(200),
 		"e_last":  float64(200),
+		"e_first": float64(200),
 		"f_count": float64(1), // f
 		"f_max":   float64(200),
 		"f_min":   float64(200),
 		"f_mean":  float64(200),
 		"f_sum":   float64(200),
 		"f_last":  float64(200),
+		"f_first": float64(200),
 		"g_count": float64(2), // g
 		"g_max":   float64(3),
 		"g_min":   float64(1),
@@ -689,6 +707,7 @@ func TestBasicStatsWithAllStats(t *testing.T) {
 		"g_stdev": math.Sqrt(2),
 		"g_sum":   float64(4),
 		"g_last":  float64(1),
+		"g_first": float64(3),
 	}
 	expectedTags := map[string]string{
 		"foo": "bar",
@@ -778,3 +797,30 @@ func TestBasicStatsWithOnlyLast(t *testing.T) {
 	}
 	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
 }
+
+func TestBasicStatsWithOnlyFirst(t *testing.T) {
+	aggregator := NewBasicStats()
+	aggregator.Stats = []string{"first"}
+	aggregator.Log = testutil.Logger{}
+	aggregator.initConfiguredStats()
+
+	aggregator.Add(m1)
+	aggregator.Add(m2)
+
+	acc := testutil.Accumulator{}
+	aggregator.Push(&acc)
+
+	expectedFields := map[string]interface{}{
+		"a_first": float64(1),
+		"b_first": float64(1),
+		"c_first": float64(2),
+		"d_first": float64(2),
+		"e_first": float64(200),
+		"f_first": float64(200),
+		"g_first": float64(3),
+	}
+	expectedTags := map[string]string{
+		"foo": "bar",
+	}
+	acc.AssertContainsTaggedFields(t, "m1", expectedFields, expectedTags)
+}

plugins/aggregators/basicstats/sample.conf

@@ -8,4 +8,4 @@
   # drop_original = false
 
   ## Configures which basic stats to push as fields
-  # stats = ["count","diff","rate","min","max","mean","non_negative_diff","non_negative_rate","percent_change","stdev","s2","sum","interval","last"]
+  # stats = ["count","min","max","mean","variance","stdev"]