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Merged
songy23 merged 3 commits into from
Nov 13, 2025
Merged

[receiver/prometheusremotewritereceiver] accept unspecified histograms #44091

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0028929
accept unspecified histograms
jelly-afk Nov 6, 2025
f43b1bf
cleanup
jelly-afk Nov 13, 2025
4cce321
Merge branch 'main' into support-unspecified-histogram
songy23 Nov 13, 2025
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27 changes: 27 additions & 0 deletions .chloggen/support-unspecified-histogram.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
# Use this changelog template to create an entry for release notes.

# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
change_type: enhancement

# The name of the component, or a single word describing the area of concern, (e.g. receiver/filelog)
component: receiver/prometheusremotewrite

# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
note: prometheusremotewrite receiver now accepts metric type unspcified histograms.

# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
issues: [41840]

# (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:

# If your change doesn't affect end users or the exported elements of any package,
# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
# Optional: The change log or logs in which this entry should be included.
# e.g. '[user]' or '[user, api]'
# Include 'user' if the change is relevant to end users.
# Include 'api' if there is a change to a library API.
# Default: '[user]'
change_logs: [user]
13 changes: 12 additions & 1 deletion receiver/prometheusremotewritereceiver/receiver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -341,7 +341,8 @@ func (prw *prometheusRemoteWriteReceiver) translateV2(_ context.Context, req *wr
description := req.Symbols[ts.Metadata.HelpRef]

// Handle histograms separately due to their complex mixed-schema processing
if ts.Metadata.Type == writev2.Metadata_METRIC_TYPE_HISTOGRAM {
if ts.Metadata.Type == writev2.Metadata_METRIC_TYPE_HISTOGRAM ||
ts.Metadata.Type == writev2.Metadata_METRIC_TYPE_UNSPECIFIED && len(ts.Histograms) > 0 {
prw.processHistogramTimeSeries(otelMetrics, ls, ts, scopeName, scopeVersion, metricName, unit, description, metricCache, &stats, modifiedResourceMetric)
continue
}
Expand Down Expand Up @@ -513,6 +514,16 @@ func (prw *prometheusRemoteWriteReceiver) processHistogramTimeSeries(
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
}
metricCache[metricIDHash] = histMetric
switch ts.Metadata.Type {
case writev2.Metadata_METRIC_TYPE_HISTOGRAM:
histMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
case writev2.Metadata_METRIC_TYPE_UNSPECIFIED:
histMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "unknown")
default:
// This default case should not be reached as this function is only called when:
// 1. ts.Metadata.Type == METRIC_TYPE_HISTOGRAM, or
// 2. ts.Metadata.Type == METRIC_TYPE_UNSPECIFIED && len(ts.Histograms) > 0
}
Comment on lines +522 to +526

@perebaj perebaj Nov 12, 2025

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Maybe the default case should return an error? This because we are talking about a not listed case/

@perebaj perebaj Nov 12, 2025

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@ArthurSens or @dashpole do you have a different opinion about it?

@jelly-afk jelly-afk Nov 13, 2025

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We shouldn't encounter any other metric types here, as we have already validated the types here

if ts.Metadata.Type == writev2.Metadata_METRIC_TYPE_HISTOGRAM || ts.Metadata.Type == writev2.Metadata_METRIC_TYPE_UNSPECIFIED && len(ts.Histograms) > 0

So it can only be either a histogram or an unspecified histogram.

@perebaj perebaj Nov 13, 2025

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What do you think if we add a comment under the default option with this info? Saying that as we are only dealing with histograms inside the processHistogramTimeSeries we don't need to define a behavior for this option.

@jelly-afk jelly-afk Nov 13, 2025

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Sounds good.

} else if len(histMetric.Description()) < len(description) {
// When the new description is longer than the existing one, we should update the metric description.
// Reference to this behavior: https://opentelemetry.io/docs/specs/otel/metrics/data-model/#opentelemetry-protocol-data-model-producer-recommendations
Expand Down
164 changes: 157 additions & 7 deletions receiver/prometheusremotewritereceiver/receiver_test.go
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Expand Up @@ -466,7 +466,7 @@ func TestTranslateV2(t *testing.T) {
cbneMetric.SetName("test_metric")
cbneMetric.SetUnit("")
cbneMetric.SetDescription("")
// cbneMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
cbneMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
hist := cbneMetric.SetEmptyHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

Expand Down Expand Up @@ -497,7 +497,7 @@ func TestTranslateV2(t *testing.T) {
expMetric.SetName("test_metric")
expMetric.SetUnit("")
expMetric.SetDescription("")
// expMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
expMetric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
expHist := expMetric.SetEmptyExponentialHistogram()
expHist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

Expand Down Expand Up @@ -744,7 +744,7 @@ func TestTranslateV2(t *testing.T) {
m.SetName("test_metric")
m.SetUnit("")
m.SetDescription("")
// m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")

hist := m.SetEmptyExponentialHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
Expand Down Expand Up @@ -828,7 +828,7 @@ func TestTranslateV2(t *testing.T) {
m.SetName("test_metric")
m.SetUnit("")
m.SetDescription("")
// m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")

hist := m.SetEmptyExponentialHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
Expand Down Expand Up @@ -891,7 +891,7 @@ func TestTranslateV2(t *testing.T) {
m := sm.Metrics().AppendEmpty()
m.SetName("test_metric")
m.SetUnit("")
// m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")

hist := m.SetEmptyExponentialHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
Expand Down Expand Up @@ -981,7 +981,7 @@ func TestTranslateV2(t *testing.T) {
m := sm.Metrics().AppendEmpty()
m.SetName("test_metric")
m.SetUnit("")
// m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")

hist := m.SetEmptyExponentialHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
Expand Down Expand Up @@ -1177,6 +1177,7 @@ func TestTranslateV2(t *testing.T) {
m1.SetName("test_hncb_histogram")
m1.SetUnit("")
m1.SetDescription("")
m1.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
hist := m1.SetEmptyHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

Expand Down Expand Up @@ -1243,6 +1244,7 @@ func TestTranslateV2(t *testing.T) {
m1.SetName("test_hncb_histogram_stale")
m1.SetUnit("")
m1.SetDescription("")
m1.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
hist := m1.SetEmptyHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

Expand Down Expand Up @@ -1395,7 +1397,7 @@ func TestTranslateV2(t *testing.T) {
m2.SetName("test_mixed_histogram")
m2.SetUnit("")
m2.SetDescription("")
// m2.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
m2.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "histogram")
hist2 := m2.SetEmptyExponentialHistogram()
hist2.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

Expand All @@ -1410,6 +1412,154 @@ func TestTranslateV2(t *testing.T) {
dp2.Positive().SetOffset(0)
dp2.Positive().BucketCounts().FromRaw([]uint64{30, 70})

return metrics
}(),
},
{
name: "unspecified histogram",
request: &writev2.Request{
Symbols: []string{
"",
"__name__", "test_metric", // 1, 2
"job", "service-x/test", // 3, 4
"instance", "107cn001", // 5, 6
"otel_scope_name", "scope1", // 7, 8
"otel_scope_version", "v1", // 9, 10
"attr1", "attr1", // 11, 12
},
Timeseries: []writev2.TimeSeries{
{
CreatedTimestamp: 1,
Metadata: writev2.Metadata{},
Histograms: []writev2.Histogram{
{
Count: &writev2.Histogram_CountInt{
CountInt: 20,
},
Sum: 30,
Timestamp: 1,
ZeroThreshold: 1,
ZeroCount: &writev2.Histogram_ZeroCountInt{
ZeroCountInt: 2,
},
Schema: -4,
PositiveSpans: []writev2.BucketSpan{{Offset: 1, Length: 2}, {Offset: 3, Length: 1}},
NegativeSpans: []writev2.BucketSpan{{Offset: 0, Length: 1}, {Offset: 2, Length: 1}},
PositiveDeltas: []int64{100, 244, 221},
NegativeDeltas: []int64{1, 2},
},
},
LabelsRefs: []uint32{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12},
},
},
},
expectedStats: remote.WriteResponseStats{
Confirmed: true,
Samples: 0,
Histograms: 1,
Exemplars: 0,
},
expectedMetrics: func() pmetric.Metrics {
metrics := pmetric.NewMetrics()
rm := metrics.ResourceMetrics().AppendEmpty()
attrs := rm.Resource().Attributes()
attrs.PutStr("service.namespace", "service-x")
attrs.PutStr("service.name", "test")
attrs.PutStr("service.instance.id", "107cn001")

sm := rm.ScopeMetrics().AppendEmpty()
sm.Scope().SetName("scope1")
sm.Scope().SetVersion("v1")

m := sm.Metrics().AppendEmpty()
m.SetName("test_metric")
m.SetUnit("")
m.SetDescription("")
m.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "unknown")

hist := m.SetEmptyExponentialHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

dp := hist.DataPoints().AppendEmpty()
dp.SetTimestamp(pcommon.Timestamp(1 * int64(time.Millisecond)))
dp.SetStartTimestamp(pcommon.Timestamp(1 * int64(time.Millisecond)))
dp.SetScale(-4)
dp.SetSum(30)
dp.SetCount(20)
dp.SetZeroCount(2)
dp.SetZeroThreshold(1)
dp.Positive().SetOffset(0)
dp.Positive().BucketCounts().FromRaw([]uint64{100, 344, 0, 0, 0, 565})
dp.Negative().BucketCounts().FromRaw([]uint64{1})
dp.Negative().SetOffset(-1)
dp.Negative().BucketCounts().FromRaw([]uint64{1, 0, 0, 3})
dp.Attributes().PutStr("attr1", "attr1")
return metrics
}(),
},
{
name: "unspecified nhcb",
request: &writev2.Request{
Symbols: []string{
"",
"__name__", "test_hncb_histogram", // 1,2
"job", "test", // 3, 4
"instance", "localhost:8080", // 5, 6
"seconds", "Test NHCB histogram", // 7, 8
},
Timeseries: []writev2.TimeSeries{
{
LabelsRefs: []uint32{1, 2, 3, 4, 5, 6},
CreatedTimestamp: 123456000,
Metadata: writev2.Metadata{},
Histograms: []writev2.Histogram{
{
Timestamp: 123456789,
Schema: -53, // NHCB schema
Sum: 100.5,
Count: &writev2.Histogram_CountInt{CountInt: 180},
CustomValues: []float64{1.0, 2.0, 5.0, 10.0}, // Custom bucket boundaries
PositiveSpans: []writev2.BucketSpan{
{Offset: 0, Length: 5}, // 5 buckets: 4 custom + 1 overflow
},
PositiveDeltas: []int64{10, 15, 20, 5, 0}, // Delta counts for each bucket
},
},
},
},
},
expectedStats: remote.WriteResponseStats{
Confirmed: true,
Samples: 0,
Histograms: 1,
Exemplars: 0,
},
expectedMetrics: func() pmetric.Metrics {
metrics := pmetric.NewMetrics()
rm := metrics.ResourceMetrics().AppendEmpty()
attrs := rm.Resource().Attributes()
attrs.PutStr("service.name", "test")
attrs.PutStr("service.instance.id", "localhost:8080")

sm := rm.ScopeMetrics().AppendEmpty()
sm.Scope().SetName("OpenTelemetry Collector")
sm.Scope().SetVersion("latest")
m1 := sm.Metrics().AppendEmpty()
m1.SetName("test_hncb_histogram")
m1.SetUnit("")
m1.SetDescription("")
m1.Metadata().PutStr(prometheus.MetricMetadataTypeKey, "unknown")
hist := m1.SetEmptyHistogram()
hist.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)

dp := hist.DataPoints().AppendEmpty()
dp.SetStartTimestamp(pcommon.Timestamp(123456000 * int64(time.Millisecond)))
dp.SetTimestamp(pcommon.Timestamp(123456789 * int64(time.Millisecond)))
dp.SetSum(100.5)
dp.SetCount(180)
dp.ExplicitBounds().FromRaw([]float64{1.0, 2.0, 5.0, 10.0})
dp.BucketCounts().FromRaw([]uint64{10, 25, 45, 50, 50})

return metrics
}(),
},
Expand Down
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