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feat(otelcol.exporter.prometheus): Add honor_metadata config argument [backport] #5439

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ptodev merged 1 commit into from
Feb 4, 2026
Merged

feat(otelcol.exporter.prometheus): Add honor_metadata config argument [backport] #5439

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32 changes: 23 additions & 9 deletions docs/sources/reference/components/otelcol/otelcol.exporter.prometheus.md
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Original file line number Diff line number Diff line change
Expand Up @@ -36,20 +36,34 @@ otelcol.exporter.prometheus "<LABEL>" {

You can use the following arguments with `otelcol.exporter.prometheus`:

| Name | Type | Description | Default | Required |
| ---------------------------------- | ----------------------- | ----------------------------------------------------------------- | ------- | -------- |
| `forward_to` | `list(MetricsReceiver)` | Where to forward converted Prometheus metrics. | | yes |
| `add_metric_suffixes` | `bool` | Whether to add type and unit suffixes to metric names. | `true` | no |
| `gc_frequency` | `duration` | How often to clean up stale metrics from memory. | `"5m"` | no |
| `include_scope_info` | `bool` | Whether to include `otel_scope_info` metrics. | `false` | no |
| `include_scope_labels` | `bool` | Whether to include additional OTLP labels in all metrics. | `true` | no |
| `include_target_info` | `bool` | Whether to include `target_info` metrics. | `true` | no |
| `resource_to_telemetry_conversion` | `bool` | Whether to convert OTel resource attributes to Prometheus labels. | `false` | no |
| Name | Type | Description | Default | Required |
| ---------------------------------- | ----------------------- | ------------------------------------------------------------------------------ | ------- | -------- |
| `forward_to` | `list(MetricsReceiver)` | Where to forward converted Prometheus metrics. | | yes |
| `add_metric_suffixes` | `bool` | Whether to add type and unit suffixes to metric names. | `true` | no |
| `gc_frequency` | `duration` | How often to clean up stale metrics from memory. | `"5m"` | no |
| `honor_metadata` | `bool` | (Experimental) Whether to send metric metadata to downstream components. | `false` | no |
| `include_scope_info` | `bool` | Whether to include `otel_scope_info` metrics. | `false` | no |
| `include_scope_labels` | `bool` | Whether to include additional OTLP labels in all metrics. | `true` | no |
| `include_target_info` | `bool` | Whether to include `target_info` metrics. | `true` | no |
| `resource_to_telemetry_conversion` | `bool` | Whether to convert OTel resource attributes to Prometheus labels. | `false` | no |

By default, OpenTelemetry resources are converted into `target_info` metrics.
OpenTelemetry instrumentation scopes are converted into `otel_scope_info` metrics.
Set the `include_scope_info` and `include_target_info` arguments to `false`, respectively, to disable the custom metrics.

{{< admonition type="warning" >}}
**EXPERIMENTAL**: The `honor_metadata` argument is an [experimental][] feature.
If you enable this argument, resource consumption may increase, particularly if you ingest many metrics with different names.
Some downstream components aren't compatible with Prometheus metadata.
The following components are compatible:

* `otelcol.receiver.prometheus`
* `prometheus.remote_write` only when configured for Remote Write v2.
* `prometheus.write_queue`

[experimental]: ../../../get-started/configuration-syntax/expressions/function_calls/#experimental-functions
{{< /admonition >}}

When `include_scope_labels` is `true` the `otel_scope_name` and `otel_scope_version` labels are added to every converted metric sample.

When `include_target_info` is true, OpenTelemetry Collector resources are converted into `target_info` metrics.
Expand Down
82 changes: 59 additions & 23 deletions internal/component/otelcol/exporter/prometheus/internal/convert/convert.go
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ type Options struct {
AddMetricSuffixes bool
// ResourceToTelemetryConversion controls whether to convert resource attributes to Prometheus-compatible datapoint attributes
ResourceToTelemetryConversion bool
HonorMetadata bool
}

var _ consumer.Metrics = (*Converter)(nil)
Expand Down Expand Up @@ -136,13 +137,18 @@ func (conv *Converter) consumeResourceMetrics(app storage.Appender, rm pmetric.R
resAttrs := rm.Resource().Attributes()
memResource := conv.getOrCreateResource(rm.Resource())

if conv.getOpts().IncludeTargetInfo {
if err := resourceMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write target_info metadata", "err", err)
}
opts := conv.getOpts()
if opts.IncludeTargetInfo {
// Write series data first, so the series exists before we write metadata.
if err := memResource.WriteTo(app, time.Now()); err != nil {
level.Error(conv.log).Log("msg", "failed to write target_info metric", "err", err)
}
// Write metadata after series data, so the series exists in the appender.
if opts.HonorMetadata {
if err := resourceMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write target_info metadata", "err", err)
}
}
}

for smcount := 0; smcount < rm.ScopeMetrics().Len(); smcount++ {
Expand Down Expand Up @@ -228,13 +234,18 @@ func (conv *Converter) consumeScopeMetrics(app storage.Appender, memResource *me
})
memScope := conv.getOrCreateScope(memResource, sm.Scope())

if conv.getOpts().IncludeScopeInfo {
if err := scopeMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write otel_scope_info metadata", "err", err)
}
opts := conv.getOpts()
if opts.IncludeScopeInfo {
// Write series data first, so the series exists before we write metadata.
if err := memScope.WriteTo(app, time.Now()); err != nil {
level.Error(conv.log).Log("msg", "failed to write otel_scope_info metric", "err", err)
}
// Write metadata after series data, so the series exists in the appender.
if opts.HonorMetadata {
if err := scopeMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write otel_scope_info metadata", "err", err)
}
}
}

for mcount := 0; mcount < sm.Metrics().Len(); mcount++ {
Expand Down Expand Up @@ -307,10 +318,8 @@ func (conv *Converter) consumeGauge(app storage.Appender, memResource *memorySer
Unit: m.Unit(),
Help: m.Description(),
})
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}

// Write series data first, so the series exists before we write metadata.
for dpcount := 0; dpcount < m.Gauge().DataPoints().Len(); dpcount++ {
dp := m.Gauge().DataPoints().At(dpcount)

Expand All @@ -323,6 +332,13 @@ func (conv *Converter) consumeGauge(app storage.Appender, memResource *memorySer
level.Error(conv.log).Log("msg", "failed to write metric sample", metricName, "err", err)
}
}

// Write metadata after series data, so the series exists in the appender.
if conv.getOpts().HonorMetadata {
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}
}
}

type otelcolDataPoint interface {
Expand Down Expand Up @@ -442,10 +458,8 @@ func (conv *Converter) consumeSum(app storage.Appender, memResource *memorySerie
Unit: m.Unit(),
Help: m.Description(),
})
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}

// Write series data first, so the series exists before we write metadata.
for dpcount := 0; dpcount < m.Sum().DataPoints().Len(); dpcount++ {
dp := m.Sum().DataPoints().At(dpcount)

Expand All @@ -468,6 +482,13 @@ func (conv *Converter) consumeSum(app storage.Appender, memResource *memorySerie
}
}
}

// Write metadata after series data, so the series exists in the appender.
if conv.getOpts().HonorMetadata {
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}
}
}

func (conv *Converter) consumeHistogram(app storage.Appender, memResource *memorySeries, memScope *memorySeries, m pmetric.Metric, resAttrs pcommon.Map) {
Expand All @@ -485,10 +506,8 @@ func (conv *Converter) consumeHistogram(app storage.Appender, memResource *memor
Unit: m.Unit(),
Help: m.Description(),
})
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}

// Write series data first, so the series exists before we write metadata.
for dpcount := 0; dpcount < m.Histogram().DataPoints().Len(); dpcount++ {
dp := m.Histogram().DataPoints().At(dpcount)

Expand Down Expand Up @@ -604,6 +623,13 @@ func (conv *Converter) consumeHistogram(app storage.Appender, memResource *memor
}
}
}

// Write metadata after series data, so the series exists in the appender.
if conv.getOpts().HonorMetadata {
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}
}
}

func (conv *Converter) consumeExponentialHistogram(app storage.Appender, memResource *memorySeries, memScope *memorySeries, m pmetric.Metric, resAttrs pcommon.Map) {
Expand All @@ -619,10 +645,8 @@ func (conv *Converter) consumeExponentialHistogram(app storage.Appender, memReso
Unit: m.Unit(),
Help: m.Description(),
})
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}

// Write series data first, so the series exists before we write metadata.
for dpcount := 0; dpcount < m.ExponentialHistogram().DataPoints().Len(); dpcount++ {
dp := m.ExponentialHistogram().DataPoints().At(dpcount)

Expand Down Expand Up @@ -657,6 +681,13 @@ func (conv *Converter) consumeExponentialHistogram(app storage.Appender, memReso
}
}
}

// Write metadata after series data, so the series exists in the appender.
if conv.getOpts().HonorMetadata {
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}
}
}

// Convert Otel Exemplar to Prometheus Exemplar.
Expand Down Expand Up @@ -695,10 +726,8 @@ func (conv *Converter) consumeSummary(app storage.Appender, memResource *memoryS
Unit: m.Unit(),
Help: m.Description(),
})
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}

// Write series data first, so the series exists before we write metadata.
for dpcount := 0; dpcount < m.Summary().DataPoints().Len(); dpcount++ {
dp := m.Summary().DataPoints().At(dpcount)

Expand Down Expand Up @@ -743,6 +772,13 @@ func (conv *Converter) consumeSummary(app storage.Appender, memResource *memoryS
}
}
}

// Write metadata after series data, so the series exists in the appender.
if conv.getOpts().HonorMetadata {
if err := metricMD.WriteTo(app, time.Now()); err != nil {
level.Warn(conv.log).Log("msg", "failed to write metric family metadata", "metric name", metricName, "err", err)
}
}
}

// GC cleans up stale metrics which have not been updated in the time specified
Expand Down
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