feat: Made sure summaries actually give output quantile objectives as well; improved flag docs and tests for complex type series calculation. (#93)

Signed-off-by: bwplotka <bwplotka@gmail.com>

Author: bwplotka

metrics/serve.go

@@ -81,7 +81,8 @@ func (c *Collector) UpdateNotifyCh() chan struct{} {
 
 type Config struct {
 	MetricCount, GaugeMetricCount, CounterMetricCount, HistogramMetricCount, NativeHistogramMetricCount, SummaryMetricCount int
-	HistogramBuckets                                                                                                        int
+
+	HistogramBuckets, SummaryObjectives int
 
 	LabelCount, SeriesCount        int
 	MaxSeriesCount, MinSeriesCount int
@@ -103,14 +104,16 @@ func NewConfigFromFlags(flagReg func(name, help string) *kingpin.FlagClause) *Co
 		IntVar(&cfg.GaugeMetricCount)
 	flagReg("counter-metric-count", "Number of counter metrics to serve.").Default("200").
 		IntVar(&cfg.CounterMetricCount)
-	flagReg("histogram-metric-count", "Number of explicit (classic) histogram metrics to serve.").Default("10").
+	flagReg("histogram-metric-count", "Number of explicit (classic) histogram metrics to serve. Use -histogram-metric-bucket-count to control number of buckets. Note that the overall number of series for a single classic histogram metric is equal to 2 (count and sum) + <histogram-metric-bucket-count> + 1 (+Inf bucket).").Default("10").
 		IntVar(&cfg.HistogramMetricCount)
-	flagReg("histogram-metric-bucket-count", "Number of explicit buckets (classic) histogram metrics.").Default("8").
+	flagReg("histogram-metric-bucket-count", "Number of explicit buckets (classic) histogram metrics, excluding +Inf bucket.").Default("7").
 		IntVar(&cfg.HistogramBuckets)
 	flagReg("native-histogram-metric-count", "Number of native (exponential) histogram metrics to serve.").Default("0").
 		IntVar(&cfg.NativeHistogramMetricCount)
-	flagReg("summary-metric-count", "Number of summary metrics to serve.").Default("0").
+	flagReg("summary-metric-count", "Number of summary metrics to serve.  Use -summary-metric-objective-count to control number of quantile objectives. Note that the overall number of series for a single summary metric is equal to 2 (count and sum) + <summary-metric-objective-count>.").Default("0").
 		IntVar(&cfg.SummaryMetricCount)
+	flagReg("summary-metric-objective-count", "Number of objectives in the summary metrics to serve.").Default("2").
+		IntVar(&cfg.SummaryObjectives)
 
 	flagReg("label-count", "Number of labels per-metric.").Default("10").
 		IntVar(&cfg.LabelCount)
@@ -242,10 +245,22 @@ func (c *Collector) recreateMetrics(unsafeGetState readOnlyStateFn) {
 		c.nativeHistograms[id] = histogram
 	}
 
+	// Mimic some quantile objectives.
+	objectives := map[float64]float64{}
+	if c.cfg.SummaryObjectives > 0 {
+		parts := 100 / c.cfg.SummaryObjectives
+		for i := 0; i < c.cfg.SummaryObjectives; i++ {
+			q := parts * (i + 1)
+			if q == 100 {
+				q = 99
+			}
+			objectives[float64(q)/100.0] = float64(100-q) / 1000.0
+		}
+	}
 	for id := range c.summaries {
 		mName := fmt.Sprintf("avalanche_summary_metric_%s_%v_%v", strings.Repeat("m", c.cfg.MetricLength), s.metricCycle, id)
 		summary := prometheus.NewSummaryVec(
-			prometheus.SummaryOpts{Name: mName, Help: help(mName)},
+			prometheus.SummaryOpts{Name: mName, Help: help(mName), Objectives: objectives},
 			append([]string{"series_id", "cycle_id"}, c.labelKeys...),
 		)
 		c.summaries[id] = summary

metrics/serve_test.go

@@ -15,6 +15,7 @@ package metrics
 
 import (
 	"fmt"
+	"math"
 	"strconv"
 	"testing"
 	"time"
@@ -40,6 +41,8 @@ func countSeries(t *testing.T, registry *prometheus.Registry) (seriesCount int)
 	return seriesCount
 }
 
+// countSeriesTypes gives exact count of all types. For complex types that are represented by counters in Prometheus
+// data model (and text exposition formats), we count all individual resulting series.
 func countSeriesTypes(t *testing.T, registry *prometheus.Registry) (gauges, counters, histograms, nhistograms, summaries int) {
 	t.Helper()
 
@@ -54,13 +57,20 @@ func countSeriesTypes(t *testing.T, registry *prometheus.Registry) (gauges, coun
 			case io_prometheus_client.MetricType_COUNTER:
 				counters++
 			case io_prometheus_client.MetricType_HISTOGRAM:
-				if len(m.GetHistogram().Bucket) == 0 {
+				if bkts := len(m.GetHistogram().Bucket); bkts == 0 {
 					nhistograms++
 				} else {
-					histograms++
+					histograms += 2 // count and sum.
+					histograms += len(m.GetHistogram().GetBucket())
+					if m.GetHistogram().GetBucket()[bkts-1].GetUpperBound() != math.Inf(+1) {
+						// In the proto model we don't put explicit +Inf bucket, unless there is an exemplar,
+						// but it will appear as series in text format and Prometheus model. Account for that.
+						histograms++
+					}
 				}
 			case io_prometheus_client.MetricType_SUMMARY:
-				summaries++
+				summaries += 2 // count and sum.
+				summaries += len(m.GetSummary().GetQuantile())
 			default:
 				t.Fatalf("unknown metric type found %v", mf.GetType())
 			}
@@ -74,9 +84,10 @@ func TestRunMetrics(t *testing.T) {
 		GaugeMetricCount:           200,
 		CounterMetricCount:         200,
 		HistogramMetricCount:       10,
-		HistogramBuckets:           8,
+		HistogramBuckets:           7,
 		NativeHistogramMetricCount: 10,
 		SummaryMetricCount:         10,
+		SummaryObjectives:          2,
 
 		MinSeriesCount: 0,
 		MaxSeriesCount: 1000,
@@ -102,19 +113,20 @@ func TestRunMetrics(t *testing.T) {
 	g, c, h, nh, s := countSeriesTypes(t, reg)
 	assert.Equal(t, testCfg.GaugeMetricCount*testCfg.SeriesCount, g)
 	assert.Equal(t, testCfg.CounterMetricCount*testCfg.SeriesCount, c)
-	assert.Equal(t, testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
+	assert.Equal(t, (2+testCfg.HistogramBuckets+1)*testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
 	assert.Equal(t, testCfg.NativeHistogramMetricCount*testCfg.SeriesCount, nh)
-	assert.Equal(t, testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
+	assert.Equal(t, (2+testCfg.SummaryObjectives)*testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
 }
 
 func TestRunMetrics_ValueChange_SeriesCountSame(t *testing.T) {
 	testCfg := Config{
 		GaugeMetricCount:           200,
 		CounterMetricCount:         200,
 		HistogramMetricCount:       10,
-		HistogramBuckets:           8,
+		HistogramBuckets:           7,
 		NativeHistogramMetricCount: 10,
 		SummaryMetricCount:         10,
+		SummaryObjectives:          2,
 
 		MinSeriesCount: 0,
 		MaxSeriesCount: 1000,
@@ -145,9 +157,9 @@ func TestRunMetrics_ValueChange_SeriesCountSame(t *testing.T) {
 		g, c, h, nh, s := countSeriesTypes(t, reg)
 		assert.Equal(t, testCfg.GaugeMetricCount*testCfg.SeriesCount, g)
 		assert.Equal(t, testCfg.CounterMetricCount*testCfg.SeriesCount, c)
-		assert.Equal(t, testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
+		assert.Equal(t, (2+testCfg.HistogramBuckets+1)*testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
 		assert.Equal(t, testCfg.NativeHistogramMetricCount*testCfg.SeriesCount, nh)
-		assert.Equal(t, testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
+		assert.Equal(t, (2+testCfg.SummaryObjectives)*testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
 	}
 }
 
@@ -184,9 +196,10 @@ func TestRunMetrics_SeriesChurn(t *testing.T) {
 		GaugeMetricCount:           200,
 		CounterMetricCount:         200,
 		HistogramMetricCount:       10,
-		HistogramBuckets:           8,
+		HistogramBuckets:           7,
 		NativeHistogramMetricCount: 10,
 		SummaryMetricCount:         10,
+		SummaryObjectives:          2,
 
 		MinSeriesCount: 0,
 		MaxSeriesCount: 1000,
@@ -220,9 +233,9 @@ func TestRunMetrics_SeriesChurn(t *testing.T) {
 		g, c, h, nh, s := countSeriesTypes(t, reg)
 		assert.Equal(t, testCfg.GaugeMetricCount*testCfg.SeriesCount, g)
 		assert.Equal(t, testCfg.CounterMetricCount*testCfg.SeriesCount, c)
-		assert.Equal(t, testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
+		assert.Equal(t, (2+testCfg.HistogramBuckets+1)*testCfg.HistogramMetricCount*testCfg.SeriesCount, h)
 		assert.Equal(t, testCfg.NativeHistogramMetricCount*testCfg.SeriesCount, nh)
-		assert.Equal(t, testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
+		assert.Equal(t, (2+testCfg.SummaryObjectives)*testCfg.SummaryMetricCount*testCfg.SeriesCount, s)
 
 		gotCycleID := currentCycleID(t, reg)
 		require.Greater(t, gotCycleID, cycleID)