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[prometheusremotewriteexporter] Support conversion of OTel Exponentia…
…l Histogram to Prometheus Native Histogram (#17370) Support conversion of OTel Exponential Histogram to Prometheus Native Histogram. pmetric.ExponentialHistogramDataPoint translates to prompb.Histogram as follows: - Exp. Scale -> Nat. Schema: histogram is dropped if Scale -4 < and > 8. - TODO: We can potentially downscale hist to 8 if Scale > 8? (as a separate PR) - Exp. Count -> Nat. Count: if Flags().NoRecordedValue() is false - Exp. Sum_ -> Nat. Sum: if it Sum is set and Flags().NoRecordedValue() is false - Exp. TimeUnixNano -> Nat. Timestamp: TimeUnixNano ns converted Timestamp ms - Exp. ZeroCount -> Nat. ZeroCount - Nat. ZeroThreshold is set to the default value 1e-128, once opentelemetry-proto#441 is merged, we can use Exp. ZeroThreshold to set the value. - Exp. Positive -> Nat. PositiveSpans and Nat. PositiveDeltas. - Exp. Negative -> Nat. NegativeSpans and Nat. NegativeDeltas. - Exp. Min_ and Max_ are not used. - Exp. StartTimeUnixNano is not used. Exp. Exemplars, Labels, and ExponentialHistogramDataPoint will be translated to native hist data structures and will make up one or more prompb.TimeSeries. Link to tracking Issue: Resolves #16207 Testing: Unit tests in pkg/transalator/prometheusremote and exporter/prometheusremotewriteexporter
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| # One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix' | ||
| change_type: enhancement | ||
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| # The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver) | ||
| component: prometheusremotewriteexporter | ||
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| # A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`). | ||
| note: Add support for converting OTLP Exponential Histograms to Prometheus Native Histograms | ||
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| # One or more tracking issues related to the change | ||
| issues: [16207] | ||
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| # (Optional) One or more lines of additional information to render under the primary note. | ||
| # These lines will be padded with 2 spaces and then inserted directly into the document. | ||
| # Use pipe (|) for multiline entries. | ||
| subtext: |
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| @@ -0,0 +1,167 @@ | ||
| // Copyright The OpenTelemetry Authors | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite" | ||
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| import ( | ||
| "fmt" | ||
| "math" | ||
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| "github.com/prometheus/common/model" | ||
| "github.com/prometheus/prometheus/model/value" | ||
| "github.com/prometheus/prometheus/prompb" | ||
| "go.opentelemetry.io/collector/pdata/pcommon" | ||
| "go.opentelemetry.io/collector/pdata/pmetric" | ||
| ) | ||
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| const defaultZeroThreshold = 1e-128 | ||
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| func addSingleExponentialHistogramDataPoint( | ||
| metric string, | ||
| pt pmetric.ExponentialHistogramDataPoint, | ||
| resource pcommon.Resource, | ||
| settings Settings, | ||
| series map[string]*prompb.TimeSeries, | ||
| ) error { | ||
| labels := createAttributes( | ||
| resource, | ||
| pt.Attributes(), | ||
| settings.ExternalLabels, | ||
| model.MetricNameLabel, metric, | ||
| ) | ||
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| sig := timeSeriesSignature( | ||
| pmetric.MetricTypeExponentialHistogram.String(), | ||
| &labels, | ||
| ) | ||
| ts, ok := series[sig] | ||
| if !ok { | ||
| ts = &prompb.TimeSeries{ | ||
| Labels: labels, | ||
| } | ||
| series[sig] = ts | ||
| } | ||
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| histogram, err := exponentialToNativeHistogram(pt) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| ts.Histograms = append(ts.Histograms, histogram) | ||
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| exemplars := getPromExemplars[pmetric.ExponentialHistogramDataPoint](pt) | ||
| ts.Exemplars = append(ts.Exemplars, exemplars...) | ||
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| return nil | ||
| } | ||
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| // exponentialToNativeHistogram translates OTel Exponential Histogram data point | ||
| // to Prometheus Native Histogram. | ||
| func exponentialToNativeHistogram(p pmetric.ExponentialHistogramDataPoint) (prompb.Histogram, error) { | ||
| scale := p.Scale() | ||
| if scale < -4 || scale > 8 { | ||
| return prompb.Histogram{}, | ||
| fmt.Errorf("cannot convert exponential to native histogram."+ | ||
| " Scale must be <= 8 and >= -4, was %d", scale) | ||
| // TODO: downscale to 8 if scale > 8 | ||
| } | ||
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| pSpans, pDeltas := convertBucketsLayout(p.Positive()) | ||
| nSpans, nDeltas := convertBucketsLayout(p.Negative()) | ||
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| h := prompb.Histogram{ | ||
| Schema: scale, | ||
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| ZeroCount: &prompb.Histogram_ZeroCountInt{ZeroCountInt: p.ZeroCount()}, | ||
| // TODO use zero_threshold, if set, see | ||
| // https://github.com/open-telemetry/opentelemetry-proto/pull/441 | ||
| ZeroThreshold: defaultZeroThreshold, | ||
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| PositiveSpans: pSpans, | ||
| PositiveDeltas: pDeltas, | ||
| NegativeSpans: nSpans, | ||
| NegativeDeltas: nDeltas, | ||
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| Timestamp: convertTimeStamp(p.Timestamp()), | ||
| } | ||
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| if p.Flags().NoRecordedValue() { | ||
| h.Sum = math.Float64frombits(value.StaleNaN) | ||
| h.Count = &prompb.Histogram_CountInt{CountInt: value.StaleNaN} | ||
| } else { | ||
| if p.HasSum() { | ||
| h.Sum = p.Sum() | ||
| } | ||
| h.Count = &prompb.Histogram_CountInt{CountInt: p.Count()} | ||
| } | ||
| return h, nil | ||
| } | ||
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| // convertBucketsLayout translates OTel Exponential Histogram dense buckets | ||
| // representation to Prometheus Native Histogram sparse bucket representation. | ||
| // | ||
| // The translation logic is taken from the client_golang `histogram.go#makeBuckets` | ||
| // function, see `makeBuckets` https://github.com/prometheus/client_golang/blob/main/prometheus/histogram.go | ||
| // The bucket indexes conversion was adjusted, since OTel exp. histogram bucket | ||
| // index 0 corresponds to the range (1, base] while Prometheus bucket index 0 | ||
| // to the range (base 1]. | ||
| func convertBucketsLayout(buckets pmetric.ExponentialHistogramDataPointBuckets) ([]*prompb.BucketSpan, []int64) { | ||
| bucketCounts := buckets.BucketCounts() | ||
| if bucketCounts.Len() == 0 { | ||
| return nil, nil | ||
| } | ||
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| var ( | ||
| spans []*prompb.BucketSpan | ||
| deltas []int64 | ||
| prevCount int64 | ||
| nextBucketIdx int32 | ||
| ) | ||
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| appendDelta := func(count int64) { | ||
| spans[len(spans)-1].Length++ | ||
| deltas = append(deltas, count-prevCount) | ||
| prevCount = count | ||
| } | ||
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| for i := 0; i < bucketCounts.Len(); i++ { | ||
| count := int64(bucketCounts.At(i)) | ||
| if count == 0 { | ||
| continue | ||
| } | ||
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| // The offset is adjusted by 1 as described above. | ||
| bucketIdx := int32(i) + buckets.Offset() + 1 | ||
| delta := bucketIdx - nextBucketIdx | ||
| if i == 0 || delta > 2 { | ||
| // We have to create a new span, either because we are | ||
| // at the very beginning, or because we have found a gap | ||
| // of more than two buckets. The constant 2 is copied from the logic in | ||
| // https://github.com/prometheus/client_golang/blob/27f0506d6ebbb117b6b697d0552ee5be2502c5f2/prometheus/histogram.go#L1296 | ||
| spans = append(spans, &prompb.BucketSpan{ | ||
| Offset: delta, | ||
| Length: 0, | ||
| }) | ||
| } else { | ||
| // We have found a small gap (or no gap at all). | ||
| // Insert empty buckets as needed. | ||
| for j := int32(0); j < delta; j++ { | ||
| appendDelta(0) | ||
| } | ||
| } | ||
| appendDelta(count) | ||
| nextBucketIdx = bucketIdx + 1 | ||
| } | ||
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| return spans, deltas | ||
| } |
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