[Exporter.Prometheus] Fix scope metadata

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/CHANGELOG.md

@@ -26,45 +26,45 @@ Notes](../../RELEASENOTES.md).
 
 * Fix non-ASCII characters in metric names and unit strings not being sanitized
   correctly during Prometheus serialization.
-  ([#7184](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7184))
+  ([#7184](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7184))
 
 * Fix case where reader tracking could be reset while readers were still active.
   ([#7190](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7190))
 
 * Improve `Accept` header handling for format negotiation so OpenMetrics is
   selected correctly by considering whitespace and `q` weights.
-  ([#7208](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7208))
+  ([#7208](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7208))
 
 * Emit OpenMetrics exemplars for counters and histogram buckets.
-  ([#7222](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7222))
+  ([#7222](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7222))
 
 * Fix incorrect handling of untyped metrics when using OpenMetrics format.
-  ([#7219](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7219))
+  ([#7219](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7219))
 
 * Fix Prometheus/OpenMetrics serialization to emit metric and label names
   containing `_` instead of dropping them and prefixing leading digits.
   Invalid characters are replaced with `_` instead of being dropped.
-  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7209))
+  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7209))
 
 * Add `escaping=underscores` to the `Accept` header handling for content
   negotiation so OpenMetrics are handled correctly.
-  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7209))
+  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7209))
 
 * Omit histogram `_sum` and `_count` in OpenMetrics when negative bucket
   thresholds are present.
-  ([#7221](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7221))
+  ([#7221](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7221))
 
 * Fix `ArgumentException` if `OTEL_SDK_DISABLED=true`.
-  ([#7273](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7273))
+  ([#7273](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7273))
 
 * Update `Accept` header parsing to more closely follow the Prometheus
   [Scrape protocol content negotiation](https://prometheus.io/docs/instrumenting/content_negotiation/)
   specification.
-  ([#7266](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7266))
+  ([#7266](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7266))
 
 * Abort scrape request processing if request exceeds the value specified by the
   `X-Prometheus-Scrape-Timeout-Seconds` HTTP request header.
-  ([#7252](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7252))
+  ([#7252](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7252))
 
 * Use the canonical representation for histogram "le" label values when using
   OpenMetrics.
@@ -84,13 +84,21 @@ Notes](../../RELEASENOTES.md).
   specified by the HTTP request headers.
   ([#7274](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7274))
 
+* Include instrumentation scope metadata on samples using `otel_scope_*` labels
+  including scope version, schema URL, and prefixed scope attributes. OpenMetrics
+  output no longer emits a separate `otel_scope_info` scope metadata metric.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Drop conflicting scope attributes named `name`, `version`, and `schema_url`.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
 ## 1.15.3-beta.1
 
 Released 2026-Apr-21
 
 * Fixed metric unit strings containing invalid Prometheus characters (e.g. `# RU`)
   not being sanitized, resulting in malformed metric names.
-  ([#6187](https://github.com/open-telemetry/opentelemetry-dotnet/issues/6187))
+  ([#7033](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7033))
 
 * Fixed Prometheus metric serialization to handle empty label names without
   throwing during scrape rendering.

src/OpenTelemetry.Exporter.Prometheus.HttpListener/CHANGELOG.md

@@ -32,7 +32,7 @@ Notes](../../RELEASENOTES.md).
 
 * Fix non-ASCII characters in metric names and unit strings not being sanitized
   correctly during Prometheus serialization.
-  ([#7184](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7184))
+  ([#7184](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7184))
 
 * Add support for caching the scrape endpoint HTTP responses using the
   `PrometheusHttpListenerOptions.ScrapeResponseCacheDurationMilliseconds` option.
@@ -45,13 +45,13 @@ Notes](../../RELEASENOTES.md).
 
 * Improve `Accept` header handling for format negotiation so OpenMetrics is
   selected correctly by considering whitespace and `q` weights.
-  ([#7208](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7208))
+  ([#7208](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7208))
 
 * Emit OpenMetrics exemplars for counters and histogram buckets.
-  ([#7222](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7222))
+  ([#7222](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7222))
 
 * Fix incorrect handling of untyped metrics when using OpenMetrics format.
-  ([#7219](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7219))
+  ([#7219](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7219))
 
 * Add support for configuring the HTTP listener endpoint host and port using
   the `OTEL_EXPORTER_PROMETHEUS_HOST` and `OTEL_EXPORTER_PROMETHEUS_PORT`
@@ -62,24 +62,24 @@ Notes](../../RELEASENOTES.md).
 * Fix Prometheus/OpenMetrics serialization to emit metric and label names
   containing and `_` instead of dropping them and prefixing leading digits.
   Invalid characters are replaced with `_` instead of being dropped.
-  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7209))
+  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7209))
 
 * Add `escaping=underscores` to the `Accept` header handling for content
   negotiation so OpenMetrics are handled correctly.
-  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7209))
+  ([#7209](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7209))
 
 * Omit histogram `_sum` and `_count` in OpenMetrics when negative bucket
   thresholds are present.
-  ([#7221](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7221))
+  ([#7221](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7221))
 
 * Update `Accept` header parsing to more closely follow the Prometheus
   [Scrape protocol content negotiation](https://prometheus.io/docs/instrumenting/content_negotiation/)
   specification.
-  ([#7266](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7266))
+  ([#7266](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7266))
 
 * Abort scrape request processing if request exceeds the value specified by the
   `X-Prometheus-Scrape-Timeout-Seconds` HTTP request header.
-  ([#7252](https://github.com/open-telemetry/opentelemetry-dotnet/issues/7252))
+  ([#7252](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7252))
 
 * Use the canonical representation for histogram "le" label values when using
   OpenMetrics.
@@ -95,13 +95,21 @@ Notes](../../RELEASENOTES.md).
   OpenMetrics and a start time is available.
   ([#7223](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7223))
 
+* Include instrumentation scope metadata on samples using `otel_scope_*` labels
+  including scope version, schema URL, and prefixed scope attributes. OpenMetrics
+  output no longer emits a separate `otel_scope_info` scope metadata metric.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
+* Drop conflicting scope attributes named `name`, `version`, and `schema_url`.
+  ([#7237](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7237))
+
 ## 1.15.3-beta.1
 
 Released 2026-Apr-21
 
 * Fixed metric unit strings containing invalid Prometheus characters (e.g. `# RU`)
   not being sanitized, resulting in malformed metric names.
-  ([#6187](https://github.com/open-telemetry/opentelemetry-dotnet/issues/6187))
+  ([#7033](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7033))
 
 * Fixed Prometheus metric serialization to handle empty label names without
   throwing during scrape rendering.

src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs

@@ -16,7 +16,6 @@ internal sealed class PrometheusCollectionManager
     private readonly long baseTimestamp = Stopwatch.GetTimestamp();
     private readonly PrometheusExporter.ExportFunc onCollectRef;
     private readonly Dictionary<Metric, PrometheusMetric> metricsCache;
-    private readonly HashSet<string> scopes;
     private int metricsCacheCount;
     private byte[] plainTextBuffer = new byte[85000]; // encourage the object to live in LOH (large object heap)
     private byte[] openMetricsBuffer = new byte[85000]; // encourage the object to live in LOH (large object heap)
@@ -39,7 +38,6 @@ public PrometheusCollectionManager(PrometheusExporter exporter)
         this.scrapeResponseCacheDuration = TimeSpan.FromMilliseconds(this.exporter.ScrapeResponseCacheDurationMilliseconds);
         this.onCollectRef = this.OnCollect;
         this.metricsCache = [];
-        this.scopes = [];
         this.GetElapsedTime = () => Stopwatch.GetElapsedTime(this.baseTimestamp);
     }
 
@@ -235,52 +233,10 @@ private ExportResult OnCollect(in Batch<Metric> metrics)
     {
         var cursor = 0;
         ref var buffer = ref (this.exporter.OpenMetricsRequested ? ref this.openMetricsBuffer : ref this.plainTextBuffer);
-
         try
         {
             cursor = this.WriteTargetInfo(ref buffer);
 
-            if (this.exporter.OpenMetricsRequested)
-            {
-                this.scopes.Clear();
-                var writeScopeMetadata = true;
-
-                foreach (var metric in metrics)
-                {
-                    if (!PrometheusSerializer.CanWriteMetric(metric))
-                    {
-                        continue;
-                    }
-
-                    if (this.scopes.Add(metric.MeterName))
-                    {
-                        while (true)
-                        {
-                            try
-                            {
-                                cursor = PrometheusSerializer.WriteScopeInfo(buffer, cursor, metric.MeterName, openMetricsRequested: true, writeMetadata: writeScopeMetadata);
-                                writeScopeMetadata = false;
-
-                                break;
-                            }
-                            catch (IndexOutOfRangeException)
-                            {
-                                if (!IncreaseBufferSize(ref buffer))
-                                {
-                                    // there are two cases we might run into the following condition:
-                                    // 1. we have many metrics to be exported - in this case we probably want
-                                    //    to put some upper limit and allow the user to configure it.
-                                    // 2. we got an IndexOutOfRangeException which was triggered by some other
-                                    //    code instead of the buffer[cursor++] - in this case we should give up
-                                    //    at certain point rather than allocating like crazy.
-                                    throw;
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-
             var metricStates = this.GetMetricStates(metrics, this.exporter.OpenMetricsRequested);
 
             foreach (var metricState in metricStates)
@@ -407,7 +363,7 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
     {
         var precomputedMetricStates = new List<PrecomputedMetricState>();
         var metadataStates = new Dictionary<string, MetadataState>(StringComparer.Ordinal);
-        var droppedMetricNames = new HashSet<string>(StringComparer.Ordinal);
+        HashSet<string>? droppedMetricNames = null;
 
         foreach (var metric in metrics)
         {
@@ -431,6 +387,7 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
 
             if (metadataState.Type != prometheusMetric.Type)
             {
+                droppedMetricNames ??= new(StringComparer.Ordinal);
                 droppedMetricNames.Add(metadataName);
                 PrometheusExporterEventSource.Log.ConflictingType(metadataName, metadataState.Type, prometheusMetric.Type);
             }
@@ -484,7 +441,7 @@ private List<MetricState> GetMetricStates(in Batch<Metric> metrics, bool openMet
 
         foreach (var metricState in precomputedMetricStates)
         {
-            if (droppedMetricNames.Contains(metricState.MetadataName))
+            if (droppedMetricNames?.Contains(metricState.MetadataName) is true)
             {
                 continue;
             }