Include resource attributes as tags for Prometheus exporters

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/.publicApi/PublicAPI.Unshipped.txt

@@ -1,6 +1,8 @@
 Microsoft.AspNetCore.Builder.PrometheusExporterApplicationBuilderExtensions
 Microsoft.AspNetCore.Builder.PrometheusExporterEndpointRouteBuilderExtensions
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions
+OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.AllowedResourceAttributesFilter.get -> System.Predicate<string>
+OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.AllowedResourceAttributesFilter.set -> void
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.DisableTotalNameSuffixForCounters.get -> bool
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.DisableTotalNameSuffixForCounters.set -> void
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.PrometheusAspNetCoreOptions() -> void

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

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+* Add resource attributes as tags for Prometheus exporters with filter
+  ([#3087](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5407))
+
 ## 1.8.0-rc.1
 
 Released 2024-Mar-27

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/OpenTelemetry.Exporter.Prometheus.AspNetCore.csproj

@@ -24,6 +24,7 @@
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusExporter.cs" Link="Includes/PrometheusExporter.cs" />
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusExporterEventSource.cs" Link="Includes/PrometheusExporterEventSource.cs" />
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusExporterOptions.cs" Link="Includes/PrometheusExporterOptions.cs" />
+    <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusResourceTagCollection.cs" Link="Includes/PrometheusResourceTagCollection.cs" />
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusSerializer.cs" Link="Includes/PrometheusSerializer.cs" />
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusSerializerExt.cs" Link="Includes/PrometheusSerializerExt.cs" />
     <Compile Include="$(RepoRoot)\src\OpenTelemetry.Exporter.Prometheus.HttpListener\Internal\PrometheusType.cs" Link="Includes/PrometheusType.cs" />

src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusAspNetCoreOptions.cs

@@ -38,5 +38,14 @@ public int ScrapeResponseCacheDurationMilliseconds
         set => this.ExporterOptions.ScrapeResponseCacheDurationMilliseconds = value;
     }
 
+    /// <summary>
+    /// Gets or sets the allowed resource attributes filter. Default value: null (no attributes allowed).
+    /// </summary>
+    public Predicate<string> AllowedResourceAttributesFilter
+    {
+        get => this.ExporterOptions.AllowedResourceAttributesFilter;
+        set => this.ExporterOptions.AllowedResourceAttributesFilter = value;
+    }
+
     internal PrometheusExporterOptions ExporterOptions { get; } = new();
 }

src/OpenTelemetry.Exporter.Prometheus.HttpListener/.publicApi/PublicAPI.Unshipped.txt

@@ -1,4 +1,6 @@
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions
+OpenTelemetry.Exporter.PrometheusHttpListenerOptions.AllowedResourceAttributesFilter.get -> System.Predicate<string>
+OpenTelemetry.Exporter.PrometheusHttpListenerOptions.AllowedResourceAttributesFilter.set -> void
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.DisableTotalNameSuffixForCounters.get -> bool
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.DisableTotalNameSuffixForCounters.set -> void
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.UriPrefixes.get -> System.Collections.Generic.IReadOnlyCollection<string>

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

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+* Add resource attributes as tags for Prometheus exporters with filter
+  ([#3087](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5407))
+
 ## 1.8.0-rc.1
 
 Released 2024-Mar-27

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

@@ -173,6 +173,8 @@ private ExportResult OnCollect(Batch<Metric> metrics)
 
         try
         {
+            var resourceTags = new PrometheusResourceTagCollection(this.exporter.Resource, this.exporter.AllowedResourceAttributesFilter);
+
             if (this.exporter.OpenMetricsRequested)
             {
                 cursor = this.WriteTargetInfo();
@@ -230,6 +232,7 @@ private ExportResult OnCollect(Batch<Metric> metrics)
                             cursor,
                             metric,
                             this.GetPrometheusMetric(metric),
+                            resourceTags,
                             this.exporter.OpenMetricsRequested);
 
                         break;

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

@@ -28,6 +28,7 @@ public PrometheusExporter(PrometheusExporterOptions options)
 
         this.ScrapeResponseCacheDurationMilliseconds = options.ScrapeResponseCacheDurationMilliseconds;
         this.DisableTotalNameSuffixForCounters = options.DisableTotalNameSuffixForCounters;
+        this.AllowedResourceAttributesFilter = options.AllowedResourceAttributesFilter;
 
         this.CollectionManager = new PrometheusCollectionManager(this);
     }
@@ -59,6 +60,8 @@ internal Func<Batch<Metric>, ExportResult> OnExport
 
     internal Resource Resource => this.resource ??= this.ParentProvider.GetResource();
 
+    internal Predicate<string> AllowedResourceAttributesFilter { get; set; }
+
     /// <inheritdoc/>
     public override ExportResult Export(in Batch<Metric> metrics)
     {

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

@@ -33,4 +33,9 @@ public int ScrapeResponseCacheDurationMilliseconds
     /// Gets or sets a value indicating whether addition of _total suffix for counter metric names is disabled. Default value: <see langword="false"/>.
     /// </summary>
     public bool DisableTotalNameSuffixForCounters { get; set; }
+
+    /// <summary>
+    /// Gets or sets the allowed resource attributes filter. Default value: null (no attributes allowed).
+    /// </summary>
+    public Predicate<string> AllowedResourceAttributesFilter { get; set; } = null;
 }

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

@@ -0,0 +1,34 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using OpenTelemetry.Resources;
+
+namespace OpenTelemetry.Exporter.Prometheus;
+
+internal readonly struct PrometheusResourceTagCollection
+{
+    private readonly Resource resource;
+    private readonly Predicate<string> resourceAttributeFilter;
+
+    public PrometheusResourceTagCollection(Resource resource, Predicate<string> resourceAttributeFilter = null)
+    {
+        this.resource = resource;
+        this.resourceAttributeFilter = resourceAttributeFilter;
+    }
+
+    public IEnumerable<KeyValuePair<string, object>> Attributes
+    {
+        get
+        {
+            if (this.resource == null || this.resourceAttributeFilter == null)
+            {
+                return Enumerable.Empty<KeyValuePair<string, object>>();
+            }
+
+            var attributeFilter = this.resourceAttributeFilter;
+
+            return this.resource?.Attributes
+                .Where(attribute => attributeFilter(attribute.Key));
+        }
+    }
+}

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

@@ -367,13 +367,19 @@ public static int WriteTimestamp(byte[] buffer, int cursor, long value, bool use
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static int WriteTags(byte[] buffer, int cursor, Metric metric, ReadOnlyTagCollection tags, bool writeEnclosingBraces = true)
+    public static int WriteTags(byte[] buffer, int cursor, Metric metric, ReadOnlyTagCollection tags, PrometheusResourceTagCollection resourceTags = default, bool writeEnclosingBraces = true)
     {
         if (writeEnclosingBraces)
         {
             buffer[cursor++] = unchecked((byte)'{');
         }
 
+        foreach (var resourceAttribute in resourceTags.Attributes)
+        {
+            cursor = WriteLabel(buffer, cursor, resourceAttribute.Key, resourceAttribute.Value);
+            buffer[cursor++] = unchecked((byte)',');
+        }
+
         cursor = WriteLabel(buffer, cursor, "otel_scope_name", metric.MeterName);
         buffer[cursor++] = unchecked((byte)',');
 

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

@@ -22,7 +22,7 @@ public static bool CanWriteMetric(Metric metric)
         return true;
     }
 
-    public static int WriteMetric(byte[] buffer, int cursor, Metric metric, PrometheusMetric prometheusMetric, bool openMetricsRequested = false)
+    public static int WriteMetric(byte[] buffer, int cursor, Metric metric, PrometheusMetric prometheusMetric, PrometheusResourceTagCollection resourceTags = default, bool openMetricsRequested = false)
     {
         cursor = WriteTypeMetadata(buffer, cursor, prometheusMetric);
         cursor = WriteUnitMetadata(buffer, cursor, prometheusMetric);
@@ -36,7 +36,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
 
                 // Counter and Gauge
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
-                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags);
+                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags, resourceTags);
 
                 buffer[cursor++] = unchecked((byte)' ');
 
@@ -87,7 +87,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
 
                     cursor = WriteMetricName(buffer, cursor, prometheusMetric);
                     cursor = WriteAsciiStringNoEscape(buffer, cursor, "_bucket{");
-                    cursor = WriteTags(buffer, cursor, metric, tags, writeEnclosingBraces: false);
+                    cursor = WriteTags(buffer, cursor, metric, tags, resourceTags, writeEnclosingBraces: false);
 
                     cursor = WriteAsciiStringNoEscape(buffer, cursor, "le=\"");
 
@@ -113,7 +113,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 // Histogram sum
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
                 cursor = WriteAsciiStringNoEscape(buffer, cursor, "_sum");
-                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags);
+                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags, resourceTags);
 
                 buffer[cursor++] = unchecked((byte)' ');
 
@@ -127,7 +127,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 // Histogram count
                 cursor = WriteMetricName(buffer, cursor, prometheusMetric);
                 cursor = WriteAsciiStringNoEscape(buffer, cursor, "_count");
-                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags);
+                cursor = WriteTags(buffer, cursor, metric, metricPoint.Tags, resourceTags);
 
                 buffer[cursor++] = unchecked((byte)' ');
 

src/OpenTelemetry.Exporter.Prometheus.HttpListener/PrometheusHttpListenerMeterProviderBuilderExtensions.cs

@@ -69,6 +69,7 @@ private static MetricReader BuildPrometheusHttpListenerMetricReader(
         {
             ScrapeResponseCacheDurationMilliseconds = 0,
             DisableTotalNameSuffixForCounters = options.DisableTotalNameSuffixForCounters,
+            AllowedResourceAttributesFilter = options.AllowedResourceAttributesFilter,
         });
 
         var reader = new BaseExportingMetricReader(exporter)

src/OpenTelemetry.Exporter.Prometheus.HttpListener/PrometheusHttpListenerOptions.cs

@@ -41,4 +41,9 @@ public IReadOnlyCollection<string> UriPrefixes
             this.uriPrefixes = value;
         }
     }
+
+    /// <summary>
+    /// Gets or sets the allowed resource attributes filter. Default value: null (no attributes allowed).
+    /// </summary>
+    public Predicate<string> AllowedResourceAttributesFilter { get; set; } = null;
 }

test/OpenTelemetry.Exporter.Prometheus.AspNetCore.Tests/PrometheusExporterMiddlewareTests.cs

@@ -248,6 +248,16 @@ public Task PrometheusExporterMiddlewareIntegration_UseOpenMetricsVersionHeader(
             acceptHeader: "application/openmetrics-text; version=1.0.0");
     }
 
+    [Fact]
+    public Task PrometheusExporterMiddlewareIntegration_AddResourceAttributesAsTags()
+    {
+        return RunPrometheusExporterMiddlewareIntegrationTest(
+            "/metrics",
+            app => app.UseOpenTelemetryPrometheusScrapingEndpoint(),
+            configureOptions: o => o.AllowedResourceAttributesFilter = s => s == "service.name",
+            addServiceNameResourceTag: true);
+    }
+
     private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
         string path,
         Action<IApplicationBuilder> configure,
@@ -256,7 +266,8 @@ private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
         bool registerMeterProvider = true,
         Action<PrometheusAspNetCoreOptions> configureOptions = null,
         bool skipMetrics = false,
-        string acceptHeader = "application/openmetrics-text")
+        string acceptHeader = "application/openmetrics-text",
+        bool addServiceNameResourceTag = false)
     {
         var requestOpenMetrics = acceptHeader.StartsWith("application/openmetrics-text");
 
@@ -325,6 +336,10 @@ private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
 
             string content = await response.Content.ReadAsStringAsync();
 
+            var resourceTagAttributes = addServiceNameResourceTag
+                ? "service_name='my_service',"
+                : string.Empty;
+
             string expected = requestOpenMetrics
                 ? "# TYPE target info\n"
                   + "# HELP target Target metadata\n"
@@ -333,10 +348,10 @@ private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
                   + "# HELP otel_scope_info Scope metadata\n"
                   + $"otel_scope_info{{otel_scope_name='{MeterName}'}} 1\n"
                   + "# TYPE counter_double_total counter\n"
-                  + $"counter_double_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+\\.\\d{{3}})\n"
+                  + $"counter_double_total{{{resourceTagAttributes}otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+\\.\\d{{3}})\n"
                   + "# EOF\n"
                 : "# TYPE counter_double_total counter\n"
-                  + $"counter_double_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+)\n"
+                  + $"counter_double_total{{{resourceTagAttributes}otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+)\n"
                   + "# EOF\n";
 
             var matches = Regex.Matches(content, ("^" + expected + "$").Replace('\'', '"'));

test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusHttpListenerTests.cs

@@ -84,6 +84,12 @@ public async Task PrometheusExporterHttpServerIntegration_UseOpenMetricsVersionH
         await this.RunPrometheusExporterHttpServerIntegrationTest(acceptHeader: "application/openmetrics-text; version=1.0.0");
     }
 
+    [Fact]
+    public async Task PrometheusExporterHttpServerIntegration_AddResourceAttributeAsTag()
+    {
+        await this.RunPrometheusExporterHttpServerIntegrationTest(addServiceNameResourceTag: true);
+    }
+
     [Fact]
     public void PrometheusHttpListenerThrowsOnStart()
     {
@@ -155,7 +161,7 @@ private static void TestPrometheusHttpListenerUriPrefixOptions(string[] uriPrefi
             });
     }
 
-    private async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetrics = false, string acceptHeader = "application/openmetrics-text")
+    private async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetrics = false, string acceptHeader = "application/openmetrics-text", bool addServiceNameResourceTag = false)
     {
         var requestOpenMetrics = acceptHeader.StartsWith("application/openmetrics-text");
 
@@ -180,6 +186,11 @@ private async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetri
                     .AddPrometheusHttpListener(options =>
                     {
                         options.UriPrefixes = new string[] { address };
+
+                        if (addServiceNameResourceTag)
+                        {
+                            options.AllowedResourceAttributesFilter = s => s == "service.name";
+                        }
                     })
                     .Build();
 
@@ -234,6 +245,10 @@ private async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetri
 
             var content = await response.Content.ReadAsStringAsync();
 
+            var resourceTagAttributes = addServiceNameResourceTag
+                ? "service_name='my_service',"
+                : string.Empty;
+
             var expected = requestOpenMetrics
                 ? "# TYPE target info\n"
                   + "# HELP target Target metadata\n"
@@ -242,10 +257,10 @@ private async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetri
                   + "# HELP otel_scope_info Scope metadata\n"
                   + $"otel_scope_info{{otel_scope_name='{MeterName}'}} 1\n"
                   + "# TYPE counter_double_total counter\n"
-                  + $"counter_double_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+\\.\\d{{3}})\n"
+                  + $"counter_double_total{{{resourceTagAttributes}otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+\\.\\d{{3}})\n"
                   + "# EOF\n"
                 : "# TYPE counter_double_total counter\n"
-                  + $"counter_double_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+)\n"
+                  + $"counter_double_total{{{resourceTagAttributes}otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',key1='value1',key2='value2'}} 101.17 (\\d+)\n"
                   + "# EOF\n";
 
             Assert.Matches(("^" + expected + "$").Replace('\'', '"'), content);

test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusSerializerTests.cs

@@ -4,6 +4,7 @@
 using System.Diagnostics.Metrics;
 using System.Text;
 using OpenTelemetry.Metrics;
+using OpenTelemetry.Resources;
 using OpenTelemetry.Tests;
 using Xunit;
 
@@ -653,8 +654,38 @@ public void HistogramOneDimensionWithScopeVersion()
             Encoding.UTF8.GetString(buffer, 0, cursor));
     }
 
-    private static int WriteMetric(byte[] buffer, int cursor, Metric metric, bool useOpenMetrics = false)
+    [Fact]
+    public void SumWithResourceAttributes()
+    {
+        var buffer = new byte[85000];
+        var metrics = new List<Metric>();
+
+        var resource = ResourceBuilder.CreateEmpty().AddService("my_service");
+
+        using var meter = new Meter(Utils.GetCurrentMethodName());
+        using var provider = Sdk.CreateMeterProviderBuilder()
+            .AddMeter(meter.Name)
+            .AddInMemoryExporter(metrics)
+            .SetResourceBuilder(resource)
+            .Build();
+
+        var counter = meter.CreateUpDownCounter<double>("test_updown_counter");
+        counter.Add(10);
+        counter.Add(-11);
+
+        provider.ForceFlush();
+
+        var cursor = WriteMetric(buffer, 0, metrics[0], true, new PrometheusResourceTagCollection(resource.Build(), s => s == "service.name"));
+        Assert.Matches(
+            ("^"
+             + "# TYPE test_updown_counter gauge\n"
+             + $"test_updown_counter{{service_name='my_service',otel_scope_name='{Utils.GetCurrentMethodName()}'}} -1 \\d+\\.\\d{{3}}\n"
+             + "$").Replace('\'', '"'),
+            Encoding.UTF8.GetString(buffer, 0, cursor));
+    }
+
+    private static int WriteMetric(byte[] buffer, int cursor, Metric metric, bool useOpenMetrics = false, PrometheusResourceTagCollection resourceTags = default)
     {
-        return PrometheusSerializer.WriteMetric(buffer, cursor, metric, PrometheusMetric.Create(metric, false), useOpenMetrics);
+        return PrometheusSerializer.WriteMetric(buffer, cursor, metric, PrometheusMetric.Create(metric, false), resourceTags, useOpenMetrics);
     }
 }