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Stabilize Prometheus Native Histogram -> OTLP (Exponential) Histogram#4898

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Stabilize Prometheus Native Histogram -> OTLP (Exponential) Histogram#4898
reyang merged 10 commits intoopen-telemetry:mainfrom
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@krajorama krajorama commented Feb 23, 2026

Fixes #4748

Changes

Enacted from #4748 (comment)

  • The counter reset header is not mentioned -added
  • Stale NaN is not defined in the document - added link to code where the bit representation can be found
  • Conversion of spans and counts is a bit hand-wavy, I understand why you'd want to link to something - added precise wording and link
  • Off by one of the offset is mentioned, but it doesn't say if it's -1 or +1 - precise now with explanation
  • NHCB (-53) schema is missing indeed - added
  • Prometheus has renamed the Created timestamp to Start timestamp to be more aligned
  • I'm not sure if the overflow buckets of native histograms are handled or how they work in OTel. Where do you count - values equal to +-Inf or values outside float64 ? - these were indeed not handled, specified now

Additionally added notes on Count and Sum for special value cases. Note that the OTel metric data model does not have "MUST" requirements on the special values or if the overall Count must be equal to the sum of all buckets.

For non-trivial changes, follow the change proposal process.

  • Related issues #
  • Related OTEP(s) #
  • Links to the prototypes (when adding or changing features)
  • CHANGELOG.md file updated for non-trivial changes
    • For trivial changes, include [chore] in the PR title to skip the changelog check
  • Spec compliance matrix updated if necessary

@krajorama krajorama requested review from a team as code owners February 23, 2026 11:01
@krajorama
Stabilize Prometheus Native Histogram -> OTLP (Exponential) Histogram
8cf1fd9 
Fixes: open-telemetry#4748

See task list in the issues comments.

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
@krajorama krajorama force-pushed the krajo/nh-prom-to-otel branch from 0a31c07 to 8cf1fd9 Compare February 23, 2026 11:10
@krajorama krajorama mentioned this pull request Feb 23, 2026
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dashpole
dashpole reviewed Feb 25, 2026
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Comment thread specification/compatibility/prometheus_and_openmetrics.md Outdated
Comment thread specification/compatibility/prometheus_and_openmetrics.md Outdated
Comment thread specification/compatibility/prometheus_and_openmetrics.md Outdated
Comment thread specification/compatibility/prometheus_and_openmetrics.md
krajorama and others added 7 commits March 11, 2026 09:34
@krajorama
Merge remote-tracking branch 'origin/main' into krajo/nh-prom-to-otel
a97f269
@krajorama
improve wording about the bucket index minus one difference
cb1e3f7 
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
@krajorama
the calculation of count
0393074 
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
@krajorama
chore: add NHCB to cspell word list
0a530fd 
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
Coded with Claude Sonnet 4.6.
@krajorama
Move NHCB to Histogram part
46d0f72 
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
@krajorama
Revert "Move NHCB to Histogram part"
06bab9f 
This reverts commit 46d0f72.
@krajorama
Merge branch 'open-telemetry:main' into krajo/nh-prom-to-otel
ff88561
dashpole
dashpole approved these changes Mar 13, 2026
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I'm OK also moving this to stable (updating the status for the section), as it matches existing implementations. If you don't move it to stable, please update the title and description

krajorama and others added 2 commits March 16, 2026 16:11
@krajorama
Merge branch 'main' into krajo/nh-prom-to-otel
bb6f023
@krajorama
set status to stable
f614789 
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
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krajorama commented Mar 16, 2026

I'm OK also moving this to stable (updating the status for the section), as it matches existing implementations. If you don't move it to stable, please update the title and description

Set to stable.

@krajorama krajorama mentioned this pull request Mar 16, 2026
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@reyang reyang added this pull request to the merge queue Mar 18, 2026
Merged via the queue into open-telemetry:main with commit 3f7b3be Mar 18, 2026
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@carlosalberto carlosalberto mentioned this pull request Apr 15, 2026
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pull Bot pushed a commit to MC-MAGA/opentelemetry-specification that referenced this pull request Apr 20, 2026
@carlosalberto @jack-berg
Release 1.56 (open-telemetry#5029)
50149c2 
### Context

- Align environment variable context propagation name restrictions with
POSIX.1-2024
  and define normalization behavior.

([open-telemetry#4944](open-telemetry#4944))
- Decouple the responsibilities of the environment variable propagation
carrier.

([open-telemetry#4961](open-telemetry#4961))
- Remove misleading implementation approach the environment variable
propagation.

([open-telemetry#5003](open-telemetry#5003))
- Change Environment Variables as Context Propagation Carriers document
status to Beta.

([open-telemetry#5020](open-telemetry#5020))

### Traces

- Stabilize Tracer `enabled` operation

([open-telemetry#4941](open-telemetry#4941))
- Stabilize `AlwaysRecord` sampler.

([open-telemetry#4934](open-telemetry#4934))

### Metrics

- Add development `maxExportBatchSize` parameter to Periodic exporting
MetricReader.

([open-telemetry#4895](open-telemetry#4895))

### Logs

- Add event to span event bridge.

([open-telemetry#5006](open-telemetry#5006))

### Resource

- Clarify that a Resource describes the observed entity, not the
component
  that technically emits telemetry.

([open-telemetry#4905](open-telemetry#4905))

### Compatibility

- Deprecate OpenTracing compatibility requirements in the specification.

([open-telemetry#4938](open-telemetry#4938))
- Stabilize sections of Prometheus and OpenMetrics Compatibility.
- Stabilize Prometheus Classic Histogram to OTLP Explicit Histogram
transformation.

([open-telemetry#4874](open-telemetry#4874))
  - Stabilize Prometheus Timestamp and Start timestamp transformation.

([open-telemetry#4953](open-telemetry#4953))
- Clarify Prometheus Native Histogram to OTLP Exponential Histogram
conversion,
add conversion rules for Native Histograms with Custom Buckets (NHCB) to
OTLP
    Histogram.

([open-telemetry#4898](open-telemetry#4898))
  - Stabilize Prometheus Dropped Types transformation.

([open-telemetry#4952](open-telemetry#4952))
- Stabilize OpenTelemetry Attributes to Prometheus labels
transformation.

([open-telemetry#4963](open-telemetry#4963))
- Stabilize Prometheus Exemplar to OpenTelemetry Exemplar
transformation.

([open-telemetry#4962](open-telemetry#4962))
  - Stabilize Prometheus Metadata transformation.

([open-telemetry#4954](open-telemetry#4954))
- Stabilize OpenTelemetry Metric Metadata to Prometheus metric metadata.

([open-telemetry#4966](open-telemetry#4966))
- Stabilize OpenTelemetry Exemplar to Prometheus Exemplar
transformation.

([open-telemetry#4964](open-telemetry#4964))
- Stabilize sections of Prometheus Metrics Exporter.
  - Stabilize host configuration.

([open-telemetry#5025](open-telemetry#5025))

### SDK Configuration

- Declarative configuration: add in-development guidance for exposing
the
  effective `Resource` returned by `Create`.

([open-telemetry#4949](open-telemetry#4949))
- Require spec changes to consider declarative config schema

([open-telemetry#4916](open-telemetry#4916))
- Add strict YAML parsing guidance to configuration supplementary
guidelines.

([open-telemetry#4878](open-telemetry#4878))

### OTEPs

- Process Context: Sharing Resource Attributes with External Readers.

([open-telemetry#4719](open-telemetry#4719))
- Support multiple Resources within an SDK.

([open-telemetry#4665](open-telemetry#4665))

---------

Co-authored-by: Jack Berg <34418638+jack-berg@users.noreply.github.com>
hilmarf pushed a commit to apeirora/opentelemetry-specification that referenced this pull request Apr 22, 2026
@carlosalberto @jack-berg @hilmarf
Release 1.56 (open-telemetry#5029)
68fba8a 
### Context

- Align environment variable context propagation name restrictions with
POSIX.1-2024
  and define normalization behavior.

([open-telemetry#4944](open-telemetry#4944))
- Decouple the responsibilities of the environment variable propagation
carrier.

([open-telemetry#4961](open-telemetry#4961))
- Remove misleading implementation approach the environment variable
propagation.

([open-telemetry#5003](open-telemetry#5003))
- Change Environment Variables as Context Propagation Carriers document
status to Beta.

([open-telemetry#5020](open-telemetry#5020))

### Traces

- Stabilize Tracer `enabled` operation

([open-telemetry#4941](open-telemetry#4941))
- Stabilize `AlwaysRecord` sampler.

([open-telemetry#4934](open-telemetry#4934))

### Metrics

- Add development `maxExportBatchSize` parameter to Periodic exporting
MetricReader.

([open-telemetry#4895](open-telemetry#4895))

### Logs

- Add event to span event bridge.

([open-telemetry#5006](open-telemetry#5006))

### Resource

- Clarify that a Resource describes the observed entity, not the
component
  that technically emits telemetry.

([open-telemetry#4905](open-telemetry#4905))

### Compatibility

- Deprecate OpenTracing compatibility requirements in the specification.

([open-telemetry#4938](open-telemetry#4938))
- Stabilize sections of Prometheus and OpenMetrics Compatibility.
- Stabilize Prometheus Classic Histogram to OTLP Explicit Histogram
transformation.

([open-telemetry#4874](open-telemetry#4874))
  - Stabilize Prometheus Timestamp and Start timestamp transformation.

([open-telemetry#4953](open-telemetry#4953))
- Clarify Prometheus Native Histogram to OTLP Exponential Histogram
conversion,
add conversion rules for Native Histograms with Custom Buckets (NHCB) to
OTLP
    Histogram.

([open-telemetry#4898](open-telemetry#4898))
  - Stabilize Prometheus Dropped Types transformation.

([open-telemetry#4952](open-telemetry#4952))
- Stabilize OpenTelemetry Attributes to Prometheus labels
transformation.

([open-telemetry#4963](open-telemetry#4963))
- Stabilize Prometheus Exemplar to OpenTelemetry Exemplar
transformation.

([open-telemetry#4962](open-telemetry#4962))
  - Stabilize Prometheus Metadata transformation.

([open-telemetry#4954](open-telemetry#4954))
- Stabilize OpenTelemetry Metric Metadata to Prometheus metric metadata.

([open-telemetry#4966](open-telemetry#4966))
- Stabilize OpenTelemetry Exemplar to Prometheus Exemplar
transformation.

([open-telemetry#4964](open-telemetry#4964))
- Stabilize sections of Prometheus Metrics Exporter.
  - Stabilize host configuration.

([open-telemetry#5025](open-telemetry#5025))

### SDK Configuration

- Declarative configuration: add in-development guidance for exposing
the
  effective `Resource` returned by `Create`.

([open-telemetry#4949](open-telemetry#4949))
- Require spec changes to consider declarative config schema

([open-telemetry#4916](open-telemetry#4916))
- Add strict YAML parsing guidance to configuration supplementary
guidelines.

([open-telemetry#4878](open-telemetry#4878))

### OTEPs

- Process Context: Sharing Resource Attributes with External Readers.

([open-telemetry#4719](open-telemetry#4719))
- Support multiple Resources within an SDK.

([open-telemetry#4665](open-telemetry#4665))

---------

Co-authored-by: Jack Berg <34418638+jack-berg@users.noreply.github.com>
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[prometheus] Stabilize Prometheus -> OTLP: Native Histograms

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