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Code Issues Releases Activity

prometheus: add histogram support to exporter (#601)

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This PR adds histogram support to the prometheus exporter.

- Adds a new aggregator selector that returns a histogram for `MeasureKind`.
  The selector can be constructed using `simple.NewWithHistogramMeasure`
- Adds support for histogram aggregators in prometheus collect method.

With this PR, the default selector is changed to use histograms.

In order to support the prometheus histogram, the `aggregator.Histogram`
interface is extended with the `Sum` method.

fixes #487

Co-authored-by: Rahul Patel <rahulpa@google.com>
This commit is contained in:
Oncilla 2020-04-01 23:36:37 +02:00 committed by GitHub
parent 857e80c270
commit 8ef02a61aa
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 115 additions and 11 deletions
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60
exporters/metric/prometheus/prometheus.go
View File

@ -43,7 +43,8 @@ type Exporter struct {
snapshot export.CheckpointSet
onError func(error)
defaultSummaryQuantiles []float64
defaultSummaryQuantiles []float64
defaultHistogramBoundaries []core.Number
}
var _ export.Exporter = &Exporter{}
@ -73,6 +74,10 @@ type Config struct {
// to use. Use nil to specify the system-default summary quantiles.
DefaultSummaryQuantiles []float64
// DefaultHistogramBoundaries defines the default histogram bucket
// boundaries.
DefaultHistogramBoundaries []core.Number
// OnError is a function that handle errors that may occur while exporting metrics.
// TODO: This should be refactored or even removed once we have a better error handling mechanism.
OnError func(error)
@ -100,11 +105,12 @@ func NewRawExporter(config Config) (*Exporter, error) {
}
e := &Exporter{
handler: promhttp.HandlerFor(config.Gatherer, promhttp.HandlerOpts{}),
registerer: config.Registerer,
gatherer: config.Gatherer,
defaultSummaryQuantiles: config.DefaultSummaryQuantiles,
onError: config.OnError,
handler: promhttp.HandlerFor(config.Gatherer, promhttp.HandlerOpts{}),
registerer: config.Registerer,
gatherer: config.Gatherer,
defaultSummaryQuantiles: config.DefaultSummaryQuantiles,
defaultHistogramBoundaries: config.DefaultHistogramBoundaries,
onError: config.OnError,
}
c := newCollector(e)
@ -138,7 +144,7 @@ func InstallNewPipeline(config Config) (*push.Controller, http.HandlerFunc, erro
// NewExportPipeline sets up a complete export pipeline with the recommended setup,
// chaining a NewRawExporter into the recommended selectors and batchers.
func NewExportPipeline(config Config, period time.Duration) (*push.Controller, http.HandlerFunc, error) {
selector := simple.NewWithExactMeasure()
selector := simple.NewWithHistogramMeasure(config.DefaultHistogramBoundaries)
exporter, err := NewRawExporter(config)
if err != nil {
return nil, nil, err
@ -204,10 +210,9 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
labels := labelValues(record.Labels())
desc := c.toDesc(&record)
// TODO: implement histogram export when the histogram aggregation is done.
// https://github.com/open-telemetry/opentelemetry-go/issues/317
if dist, ok := agg.(aggregator.Distribution); ok {
if hist, ok := agg.(aggregator.Histogram); ok {
c.exportHistogram(ch, hist, numberKind, desc, labels)
} else if dist, ok := agg.(aggregator.Distribution); ok {
// TODO: summaries values are never being resetted.
// As measures are recorded, new records starts to have less impact on these summaries.
// We should implement an solution that is similar to the Prometheus Clients
@ -287,6 +292,39 @@ func (c *collector) exportSummary(ch chan<- prometheus.Metric, dist aggregator.D
ch <- m
}
func (c *collector) exportHistogram(ch chan<- prometheus.Metric, hist aggregator.Histogram, kind core.NumberKind, desc *prometheus.Desc, labels []string) {
buckets, err := hist.Histogram()
if err != nil {
c.exp.onError(err)
return
}
sum, err := hist.Sum()
if err != nil {
c.exp.onError(err)
return
}
var totalCount uint64
// counts maps from the bucket upper-bound to the cumulative count.
// The bucket with upper-bound +inf is not included.
counts := make(map[float64]uint64, len(buckets.Boundaries))
for i := range buckets.Boundaries {
boundary := buckets.Boundaries[i].CoerceToFloat64(kind)
totalCount += buckets.Counts[i].AsUint64()
counts[boundary] = totalCount
}
// Include the +inf bucket in the total count.
totalCount += buckets.Counts[len(buckets.Counts)-1].AsUint64()
m, err := prometheus.NewConstHistogram(desc, totalCount, sum.CoerceToFloat64(kind), counts, labels...)
if err != nil {
c.exp.onError(err)
return
}
ch <- m
}
func (c *collector) toDesc(record *export.Record) *prometheus.Desc {
desc := record.Descriptor()
labels := labelsKeys(record.Labels())

27
exporters/metric/prometheus/prometheus_test.go
View File

@ -49,6 +49,8 @@ func TestPrometheusExporter(t *testing.T) {
"lastvalue", metric.ObserverKind, core.Float64NumberKind)
measure := metric.NewDescriptor(
"measure", metric.MeasureKind, core.Float64NumberKind)
histogramMeasure := metric.NewDescriptor(
"histogram_measure", metric.MeasureKind, core.Float64NumberKind)
labels := []core.KeyValue{
key.New("A").String("B"),
@ -70,6 +72,18 @@ func TestPrometheusExporter(t *testing.T) {
expected = append(expected, `measure_sum{A="B",C="D"} 45`)
expected = append(expected, `measure_count{A="B",C="D"} 3`)
boundaries := []core.Number{core.NewFloat64Number(-0.5), core.NewFloat64Number(1)}
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, -0.6, labels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, -0.4, labels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, 0.6, labels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, 20, labels...)
expected = append(expected, `histogram_measure_bucket{A="B",C="D",le="+Inf"} 4`)
expected = append(expected, `histogram_measure_bucket{A="B",C="D",le="-0.5"} 1`)
expected = append(expected, `histogram_measure_bucket{A="B",C="D",le="1"} 3`)
expected = append(expected, `histogram_measure_count{A="B",C="D"} 4`)
expected = append(expected, `histogram_measure_sum{A="B",C="D"} 19.6`)
missingLabels := []core.KeyValue{
key.New("A").String("E"),
key.New("C").String(""),
@ -88,6 +102,19 @@ func TestPrometheusExporter(t *testing.T) {
expected = append(expected, `measure_count{A="E",C=""} 1`)
expected = append(expected, `measure_sum{A="E",C=""} 19`)
boundaries = []core.Number{core.NewFloat64Number(0), core.NewFloat64Number(1)}
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, -0.6, missingLabels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, -0.4, missingLabels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, -0.1, missingLabels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, 15, missingLabels...)
checkpointSet.AddHistogramMeasure(&histogramMeasure, boundaries, 15, missingLabels...)
expected = append(expected, `histogram_measure_bucket{A="E",C="",le="+Inf"} 5`)
expected = append(expected, `histogram_measure_bucket{A="E",C="",le="0"} 3`)
expected = append(expected, `histogram_measure_bucket{A="E",C="",le="1"} 3`)
expected = append(expected, `histogram_measure_count{A="E",C=""} 5`)
expected = append(expected, `histogram_measure_sum{A="E",C=""} 28.9`)
compareExport(t, exporter, checkpointSet, expected)
}

5
exporters/metric/test/test.go
View File

@ -23,6 +23,7 @@ import (
export "go.opentelemetry.io/otel/sdk/export/metric"
"go.opentelemetry.io/otel/sdk/export/metric/aggregator"
"go.opentelemetry.io/otel/sdk/metric/aggregator/array"
"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
"go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue"
"go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
)
@ -84,6 +85,10 @@ func (p *CheckpointSet) AddMeasure(desc *metric.Descriptor, v float64, labels ..
p.updateAggregator(desc, array.New(), v, labels...)
}
func (p *CheckpointSet) AddHistogramMeasure(desc *metric.Descriptor, boundaries []core.Number, v float64, labels ...core.KeyValue) {
p.updateAggregator(desc, histogram.New(desc, boundaries), v, labels...)
}
func (p *CheckpointSet) updateAggregator(desc *metric.Descriptor, newAgg export.Aggregator, v float64, labels ...core.KeyValue) {
ctx := context.Background()
// Updates and checkpoint the new aggregator

1
sdk/export/metric/aggregator/aggregator.go
View File

@ -75,6 +75,7 @@ type (
// Histogram returns the count of events in pre-determined buckets.
Histogram interface {
Sum
Histogram() (Buckets, error)
}

25
sdk/metric/selector/simple/simple.go
View File

@ -15,10 +15,12 @@
package simple // import "go.opentelemetry.io/otel/sdk/metric/selector/simple"
import (
"go.opentelemetry.io/otel/api/core"
"go.opentelemetry.io/otel/api/metric"
export "go.opentelemetry.io/otel/sdk/export/metric"
"go.opentelemetry.io/otel/sdk/metric/aggregator/array"
"go.opentelemetry.io/otel/sdk/metric/aggregator/ddsketch"
"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
"go.opentelemetry.io/otel/sdk/metric/aggregator/minmaxsumcount"
"go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
)
@ -29,12 +31,16 @@ type (
selectorSketch struct {
config *ddsketch.Config
}
selectorHistogram struct {
boundaries []core.Number
}
)
var (
_ export.AggregationSelector = selectorInexpensive{}
_ export.AggregationSelector = selectorSketch{}
_ export.AggregationSelector = selectorExact{}
_ export.AggregationSelector = selectorHistogram{}
)
// NewWithInexpensiveMeasure returns a simple aggregation selector
@ -66,6 +72,14 @@ func NewWithExactMeasure() export.AggregationSelector {
return selectorExact{}
}
// NewWithHistogramMeasure returns a simple aggregation selector that uses counter,
// histogram, and histogram aggregators for the three kinds of metric. This
// selector uses more memory than the NewWithInexpensiveMeasure because it
// uses a counter per bucket.
func NewWithHistogramMeasure(boundaries []core.Number) export.AggregationSelector {
return selectorHistogram{boundaries: boundaries}
}
func (selectorInexpensive) AggregatorFor(descriptor *metric.Descriptor) export.Aggregator {
switch descriptor.MetricKind() {
case metric.ObserverKind:
@ -98,3 +112,14 @@ func (selectorExact) AggregatorFor(descriptor *metric.Descriptor) export.Aggrega
return sum.New()
}
}
func (s selectorHistogram) AggregatorFor(descriptor *metric.Descriptor) export.Aggregator {
switch descriptor.MetricKind() {
case metric.ObserverKind:
fallthrough
case metric.MeasureKind:
return histogram.New(descriptor, s.boundaries)
default:
return sum.New()
}
}

8
sdk/metric/selector/simple/simple_test.go
View File

@ -23,6 +23,7 @@ import (
"go.opentelemetry.io/otel/api/metric"
"go.opentelemetry.io/otel/sdk/metric/aggregator/array"
"go.opentelemetry.io/otel/sdk/metric/aggregator/ddsketch"
"go.opentelemetry.io/otel/sdk/metric/aggregator/histogram"
"go.opentelemetry.io/otel/sdk/metric/aggregator/minmaxsumcount"
"go.opentelemetry.io/otel/sdk/metric/aggregator/sum"
"go.opentelemetry.io/otel/sdk/metric/selector/simple"
@ -54,3 +55,10 @@ func TestExactMeasure(t *testing.T) {
require.NotPanics(t, func() { _ = ex.AggregatorFor(&testMeasureDesc).(*array.Aggregator) })
require.NotPanics(t, func() { _ = ex.AggregatorFor(&testObserverDesc).(*array.Aggregator) })
}
func TestHistogramMeasure(t *testing.T) {
ex := simple.NewWithHistogramMeasure([]core.Number{})
require.NotPanics(t, func() { _ = ex.AggregatorFor(&testCounterDesc).(*sum.Aggregator) })
require.NotPanics(t, func() { _ = ex.AggregatorFor(&testMeasureDesc).(*histogram.Aggregator) })
require.NotPanics(t, func() { _ = ex.AggregatorFor(&testObserverDesc).(*histogram.Aggregator) })
}