1414
1515package prometheus // import "go.opentelemetry.io/otel/exporters/metric/prometheus"
1616
17+ // Note that this package does not support a way to export Prometheus
18+ // Summary data points, removed in PR#1412.
19+
1720import (
1821 "context"
1922 "fmt"
@@ -50,10 +53,13 @@ type Exporter struct {
5053 lock sync.RWMutex
5154 controller * pull.Controller
5255
53- defaultSummaryQuantiles []float64
5456 defaultHistogramBoundaries []float64
5557}
5658
59+ // ErrUnsupportedAggregator is returned for unrepresentable aggregator
60+ // types (e.g., exact).
61+ var ErrUnsupportedAggregator = fmt .Errorf ("unsupported aggregator type" )
62+
5763var _ http.Handler = & Exporter {}
5864
5965// Config is a set of configs for the tally reporter.
@@ -76,10 +82,6 @@ type Config struct {
7682 // If not specified the Registry will be used as default.
7783 Gatherer prometheus.Gatherer
7884
79- // DefaultSummaryQuantiles is the default summary quantiles
80- // to use. Use nil to specify the system-default summary quantiles.
81- DefaultSummaryQuantiles []float64
82-
8385 // DefaultHistogramBoundaries defines the default histogram bucket
8486 // boundaries.
8587 DefaultHistogramBoundaries []float64
@@ -104,7 +106,6 @@ func NewExportPipeline(config Config, options ...pull.Option) (*Exporter, error)
104106 handler : promhttp .HandlerFor (config .Gatherer , promhttp.HandlerOpts {}),
105107 registerer : config .Registerer ,
106108 gatherer : config .Gatherer ,
107- defaultSummaryQuantiles : config .DefaultSummaryQuantiles ,
108109 defaultHistogramBoundaries : config .DefaultHistogramBoundaries ,
109110 }
110111
@@ -167,15 +168,12 @@ func (e *Exporter) Controller() *pull.Controller {
167168 return e .controller
168169}
169170
171+ // ExportKindFor implements ExportKindSelector.
170172func (e * Exporter ) ExportKindFor (desc * metric.Descriptor , kind aggregation.Kind ) export.ExportKind {
171- // NOTE: Summary values should use Delta aggregation, then be
172- // combined into a sliding window, see the TODO below.
173- // NOTE: Prometheus also supports a "GaugeDelta" exposition format,
174- // which is expressed as a delta histogram. Need to understand if this
175- // should be a default behavior for ValueRecorder/ValueObserver.
176173 return export .CumulativeExportKindSelector ().ExportKindFor (desc , kind )
177174}
178175
176+ // ServeHTTP implements http.Handler.
179177func (e * Exporter ) ServeHTTP (w http.ResponseWriter , r * http.Request ) {
180178 e .handler .ServeHTTP (w , r )
181179}
@@ -187,6 +185,7 @@ type collector struct {
187185
188186var _ prometheus.Collector = (* collector )(nil )
189187
188+ // Describe implements prometheus.Collector.
190189func (c * collector ) Describe (ch chan <- * prometheus.Desc ) {
191190 c .exp .lock .RLock ()
192191 defer c .exp .lock .RUnlock ()
@@ -226,18 +225,6 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
226225 if err := c .exportHistogram (ch , hist , numberKind , desc , labels ); err != nil {
227226 return fmt .Errorf ("exporting histogram: %w" , err )
228227 }
229- } else if dist , ok := agg .(aggregation.Distribution ); ok {
230- // TODO: summaries values are never being resetted.
231- // As measurements are recorded, new records starts to have less impact on these summaries.
232- // We should implement an solution that is similar to the Prometheus Clients
233- // using a rolling window for summaries could be a solution.
234- //
235- // References:
236- // https://www.robustperception.io/how-does-a-prometheus-summary-work
237- // https://github.com/prometheus/client_golang/blob/fa4aa9000d2863904891d193dea354d23f3d712a/prometheus/summary.go#L135
238- if err := c .exportSummary (ch , dist , numberKind , desc , labels ); err != nil {
239- return fmt .Errorf ("exporting summary: %w" , err )
240- }
241228 } else if sum , ok := agg .(aggregation.Sum ); ok && instrumentKind .Monotonic () {
242229 if err := c .exportMonotonicCounter (ch , sum , numberKind , desc , labels ); err != nil {
243230 return fmt .Errorf ("exporting monotonic counter: %w" , err )
@@ -250,6 +237,8 @@ func (c *collector) Collect(ch chan<- prometheus.Metric) {
250237 if err := c .exportLastValue (ch , lastValue , numberKind , desc , labels ); err != nil {
251238 return fmt .Errorf ("exporting last value: %w" , err )
252239 }
240+ } else {
241+ return fmt .Errorf ("%w: %s" , ErrUnsupportedAggregator , agg .Kind ())
253242 }
254243 return nil
255244 })
@@ -303,33 +292,6 @@ func (c *collector) exportMonotonicCounter(ch chan<- prometheus.Metric, sum aggr
303292 return nil
304293}
305294
306- func (c * collector ) exportSummary (ch chan <- prometheus.Metric , dist aggregation.Distribution , kind number.Kind , desc * prometheus.Desc , labels []string ) error {
307- count , err := dist .Count ()
308- if err != nil {
309- return fmt .Errorf ("error retrieving count: %w" , err )
310- }
311-
312- var sum number.Number
313- sum , err = dist .Sum ()
314- if err != nil {
315- return fmt .Errorf ("error retrieving distribution sum: %w" , err )
316- }
317-
318- quantiles := make (map [float64 ]float64 )
319- for _ , quantile := range c .exp .defaultSummaryQuantiles {
320- q , _ := dist .Quantile (quantile )
321- quantiles [quantile ] = q .CoerceToFloat64 (kind )
322- }
323-
324- m , err := prometheus .NewConstSummary (desc , uint64 (count ), sum .CoerceToFloat64 (kind ), quantiles , labels ... )
325- if err != nil {
326- return fmt .Errorf ("error creating constant summary: %w" , err )
327- }
328-
329- ch <- m
330- return nil
331- }
332-
333295func (c * collector ) exportHistogram (ch chan <- prometheus.Metric , hist aggregation.Histogram , kind number.Kind , desc * prometheus.Desc , labels []string ) error {
334296 buckets , err := hist .Histogram ()
335297 if err != nil {
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