Add scope info and version to Prometheus exporter

open-telemetry · Nov 27, 2023 · 665537c · 665537c
1 parent eec09c9
commit 665537c
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Showing 6 changed files with 116 additions and 10 deletions.
diff --git a/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusAspNetCoreOptions.cs b/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusAspNetCoreOptions.cs
@@ -42,5 +42,14 @@ public int ScrapeResponseCacheDurationMilliseconds
         set => this.ExporterOptions.ScrapeResponseCacheDurationMilliseconds = value;
     }
 
+    /// <summary>
+    /// Gets or sets the ability to export metric scope info. Default value: true.
+    /// </summary>
+    public bool ScopeInfoEnabled
+    {
+        get => this.ExporterOptions.ScopeInfoEnabled;
+        set => this.ExporterOptions.ScopeInfoEnabled = value;
+    }
+
     internal PrometheusExporterOptions ExporterOptions { get; } = new();
 }
diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs
@@ -182,19 +182,23 @@ private ExportResult OnCollect(Batch<Metric> metrics)
 
         try
         {
-            foreach (var metric in metrics)
+            if (this.exporter.ScopeInfoEnabled)
             {
-                if (!PrometheusSerializer.CanWriteMetric(metric))
+                var scopes = new HashSet<string>();
+
+                foreach (var metric in metrics)
                 {
-                    continue;
+                    if (PrometheusSerializer.CanWriteMetric(metric))
+                    {
+                        scopes.Add(metric.MeterName);
+                    }
                 }
 
-                while (true)
+                foreach (var scope in scopes)
                 {
                     try
                     {
-                        cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric));
-                        break;
+                        cursor = PrometheusSerializer.WriteScopeInfo(this.buffer, cursor, scope);
                     }
                     catch (IndexOutOfRangeException)
                     {
@@ -212,6 +216,30 @@ private ExportResult OnCollect(Batch<Metric> metrics)
                 }
             }
 
+            foreach (var metric in metrics)
+            {
+                if (!PrometheusSerializer.CanWriteMetric(metric))
+                {
+                    continue;
+                }
+
+                while (true)
+                {
+                    try
+                    {
+                        cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric), this.exporter.ScopeInfoEnabled);
+                        break;
+                    }
+                    catch (IndexOutOfRangeException)
+                    {
+                        if (!this.IncreaseBufferSize())
+                        {
+                            throw;
+                        }
+                    }
+                }
+            }
+
             while (true)
             {
                 try

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs
@@ -38,6 +38,7 @@ public PrometheusExporter(PrometheusExporterOptions options)
         Guard.ThrowIfNull(options);
 
         this.ScrapeResponseCacheDurationMilliseconds = options.ScrapeResponseCacheDurationMilliseconds;
+        this.ScopeInfoEnabled = options.ScopeInfoEnabled;
 
         this.CollectionManager = new PrometheusCollectionManager(this);
     }
@@ -63,6 +64,8 @@ public PrometheusExporter(PrometheusExporterOptions options)
 
     internal int ScrapeResponseCacheDurationMilliseconds { get; }
 
+    internal bool ScopeInfoEnabled { get; }
+
     /// <inheritdoc/>
     public override ExportResult Export(in Batch<Metric> metrics)
     {

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporterOptions.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporterOptions.cs
@@ -41,4 +41,9 @@ public int ScrapeResponseCacheDurationMilliseconds
             this.scrapeResponseCacheDurationMilliseconds = value;
         }
     }
+
+    /// <summary>
+    /// Gets or sets the ability to export metric scope info. Default value: true.
+    /// </summary>
+    public bool ScopeInfoEnabled { get; set; } = true;
 }
diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs
@@ -326,6 +326,31 @@ public static int WriteUnitMetadata(byte[] buffer, int cursor, PrometheusMetric
         return cursor;
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int WriteScopeInfo(byte[] buffer, int cursor, string scopeName)
+    {
+        if (string.IsNullOrEmpty(scopeName))
+        {
+            return cursor;
+        }
+
+        cursor = WriteAsciiStringNoEscape(buffer, cursor, "# TYPE otel_scope_info info");
+        buffer[cursor++] = ASCII_LINEFEED;
+
+        cursor = WriteAsciiStringNoEscape(buffer, cursor, "# HELP otel_scope_info Scope metadata");
+        buffer[cursor++] = ASCII_LINEFEED;
+
+        cursor = WriteAsciiStringNoEscape(buffer, cursor, "otel_scope_info");
+        buffer[cursor++] = unchecked((byte)'{');
+        cursor = WriteLabel(buffer, cursor, "otel_scope_name", scopeName);
+        buffer[cursor++] = unchecked((byte)'}');
+        buffer[cursor++] = unchecked((byte)' ');
+        buffer[cursor++] = unchecked((byte)'1');
+        buffer[cursor++] = ASCII_LINEFEED;
+
+        return cursor;
+    }
+
     private static string MapPrometheusType(PrometheusType type)
     {
         return type switch

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializerExt.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializerExt.cs
@@ -35,7 +35,7 @@ public static bool CanWriteMetric(Metric metric)
         return true;
     }
 
-    public static int WriteMetric(byte[] buffer, int cursor, Metric metric, PrometheusMetric prometheusMetric)
+    public static int WriteMetric(byte[] buffer, int cursor, Metric metric, PrometheusMetric prometheusMetric, bool scopeInfoEnabled)
     {
         cursor = WriteTypeMetadata(buffer, cursor, prometheusMetric);
         cursor = WriteUnitMetadata(buffer, cursor, prometheusMetric);
@@ -51,10 +51,22 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 // Counter and Gauge
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
 
-                if (tags.Count > 0)
+                if (tags.Count > 0 || scopeInfoEnabled)
                 {
                     buffer[cursor++] = unchecked((byte)'{');
 
+                    if (scopeInfoEnabled)
+                    {
+                        cursor = WriteLabel(buffer, cursor, "otel_scope_name", metric.MeterName);
+                        buffer[cursor++] = unchecked((byte)',');
+
+                        if (!string.IsNullOrEmpty(metric.MeterVersion))
+                        {
+                            cursor = WriteLabel(buffer, cursor, "otel_scope_version", metric.MeterVersion);
+                            buffer[cursor++] = unchecked((byte)',');
+                        }
+                    }
+
                     foreach (var tag in tags)
                     {
                         cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);
@@ -145,10 +157,22 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
                 cursor = WriteAsciiStringNoEscape(buffer, cursor, "_sum");
 
-                if (tags.Count > 0)
+                if (tags.Count > 0 || scopeInfoEnabled)
                 {
                     buffer[cursor++] = unchecked((byte)'{');
 
+                    if (scopeInfoEnabled)
+                    {
+                        cursor = WriteLabel(buffer, cursor, "otel_scope_name", metric.MeterName);
+                        buffer[cursor++] = unchecked((byte)',');
+
+                        if (!string.IsNullOrEmpty(metric.MeterVersion))
+                        {
+                            cursor = WriteLabel(buffer, cursor, "otel_scope_version", metric.MeterVersion);
+                            buffer[cursor++] = unchecked((byte)',');
+                        }
+                    }
+
                     foreach (var tag in tags)
                     {
                         cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);
@@ -171,10 +195,22 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
                 cursor = WriteAsciiStringNoEscape(buffer, cursor, "_count");
 
-                if (tags.Count > 0)
+                if (tags.Count > 0 || scopeInfoEnabled)
                 {
                     buffer[cursor++] = unchecked((byte)'{');
 
+                    if (scopeInfoEnabled)
+                    {
+                        cursor = WriteLabel(buffer, cursor, "otel_scope_name", metric.MeterName);
+                        buffer[cursor++] = unchecked((byte)',');
+
+                        if (!string.IsNullOrEmpty(metric.MeterVersion))
+                        {
+                            cursor = WriteLabel(buffer, cursor, "otel_scope_version", metric.MeterVersion);
+                            buffer[cursor++] = unchecked((byte)',');
+                        }
+                    }
+
                     foreach (var tag in tags)
                     {
                         cursor = WriteLabel(buffer, cursor, tag.Key, tag.Value);