Optionally disable timestamps in the 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.DisableTimestamp.get -> bool
+OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.DisableTimestamp.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

@@ -16,6 +16,9 @@ Notes](../../RELEASENOTES.md).
 * Add support for .NET 10.0.
   ([#6307](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6307))
 
+* Added the possibility to disable timestamps via the `PrometheusAspNetCoreOptions`.
+  ([#6600](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6600))
+
 ## 1.13.1-beta.1
 
 Released 2025-Oct-10

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

@@ -38,5 +38,14 @@ public int ScrapeResponseCacheDurationMilliseconds
         set => this.ExporterOptions.ScrapeResponseCacheDurationMilliseconds = value;
     }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether timestamps should be disabled. Default value: <see langword="false"/>.
+    /// </summary>
+    public bool DisableTimestamp
+    {
+        get => this.ExporterOptions.DisableTimestamp;
+        set => this.ExporterOptions.DisableTimestamp = 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.DisableTimestamp.get -> bool
+OpenTelemetry.Exporter.PrometheusHttpListenerOptions.DisableTimestamp.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

@@ -16,6 +16,9 @@ Notes](../../RELEASENOTES.md).
 * Add support for .NET 10.0.
   ([#6307](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6307))
 
+* Added the possibility to disable timestamps via the `PrometheusHttpListenerOptions`.
+  ([#6600](https://github.com/open-telemetry/opentelemetry-dotnet/pull/6600))
+
 ## 1.13.1-beta.1
 
 Released 2025-Oct-10

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

@@ -275,7 +275,8 @@ private ExportResult OnCollect(in Batch<Metric> metrics)
                             cursor,
                             metric,
                             this.GetPrometheusMetric(metric),
-                            this.exporter.OpenMetricsRequested);
+                            this.exporter.OpenMetricsRequested,
+                            this.exporter.DisableTimestamp);
 
                         break;
                     }

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

@@ -27,6 +27,7 @@ public PrometheusExporter(PrometheusExporterOptions options)
 
         this.ScrapeResponseCacheDurationMilliseconds = options.ScrapeResponseCacheDurationMilliseconds;
         this.DisableTotalNameSuffixForCounters = options.DisableTotalNameSuffixForCounters;
+        this.DisableTimestamp = options.DisableTimestamp;
 
         this.CollectionManager = new PrometheusCollectionManager(this);
     }
@@ -50,6 +51,8 @@ public PrometheusExporter(PrometheusExporterOptions options)
 
     internal bool OpenMetricsRequested { get; set; }
 
+    internal bool DisableTimestamp { get; set; }
+
     internal Resource Resource => this.resource ??= this.ParentProvider.GetResource();
 
     /// <inheritdoc/>

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 a value indicating whether timestamps should be disabled. Default value: <see langword="false"/>.
+    /// </summary>
+    public bool DisableTimestamp { get; set; }
 }

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, bool openMetricsRequested, bool disableTimestamp)
     {
         cursor = WriteTypeMetadata(buffer, cursor, prometheusMetric, openMetricsRequested);
         cursor = WriteUnitMetadata(buffer, cursor, prometheusMetric, openMetricsRequested);
@@ -66,9 +66,11 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                     }
                 }
 
-                buffer[cursor++] = unchecked((byte)' ');
-
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                if (!disableTimestamp)
+                {
+                    buffer[cursor++] = unchecked((byte)' ');
+                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                }
 
                 buffer[cursor++] = ASCII_LINEFEED;
             }
@@ -103,9 +105,12 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                     cursor = WriteAsciiStringNoEscape(buffer, cursor, "\"} ");
 
                     cursor = WriteLong(buffer, cursor, totalCount);
-                    buffer[cursor++] = unchecked((byte)' ');
 
-                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                    if (!disableTimestamp)
+                    {
+                        buffer[cursor++] = unchecked((byte)' ');
+                        cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                    }
 
                     buffer[cursor++] = ASCII_LINEFEED;
                 }
@@ -118,9 +123,12 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 buffer[cursor++] = unchecked((byte)' ');
 
                 cursor = WriteDouble(buffer, cursor, metricPoint.GetHistogramSum());
-                buffer[cursor++] = unchecked((byte)' ');
 
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                if (!disableTimestamp)
+                {
+                    buffer[cursor++] = unchecked((byte)' ');
+                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                }
 
                 buffer[cursor++] = ASCII_LINEFEED;
 
@@ -132,9 +140,12 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 buffer[cursor++] = unchecked((byte)' ');
 
                 cursor = WriteLong(buffer, cursor, metricPoint.GetHistogramCount());
-                buffer[cursor++] = unchecked((byte)' ');
 
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                if (!disableTimestamp)
+                {
+                    buffer[cursor++] = unchecked((byte)' ');
+                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
+                }
 
                 buffer[cursor++] = ASCII_LINEFEED;
             }

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

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

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

@@ -24,6 +24,11 @@ public class PrometheusHttpListenerOptions
     /// </summary>
     public bool DisableTotalNameSuffixForCounters { get; set; }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether timestamps should be disabled. Default value: <see langword="false"/>.
+    /// </summary>
+    public bool DisableTimestamp { get; set; }
+
     /// <summary>
     /// Gets or sets the URI (Uniform Resource Identifier) prefixes to use for the http listener.
     /// Default value: <c>["http://localhost:9464/"]</c>.

test/Benchmarks/Exporter/PrometheusSerializerBenchmarks.cs

@@ -59,7 +59,7 @@ public void WriteMetric()
             int cursor = 0;
             foreach (var metric in this.metrics)
             {
-                cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric));
+                cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric), openMetricsRequested: false, disableTimestamp: false);
             }
         }
     }

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

@@ -51,13 +51,19 @@ public Task PrometheusExporterMiddlewareIntegration_OptionsFallback()
             services => services.Configure<PrometheusAspNetCoreOptions>(o => o.ScrapeEndpointPath = null));
     }
 
-    [Fact]
-    public Task PrometheusExporterMiddlewareIntegration_OptionsViaAddPrometheusExporter()
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public Task PrometheusExporterMiddlewareIntegration_OptionsViaAddPrometheusExporter(bool disableTimestamp)
     {
         return RunPrometheusExporterMiddlewareIntegrationTest(
             "/metrics_from_AddPrometheusExporter",
             app => app.UseOpenTelemetryPrometheusScrapingEndpoint(),
-            configureOptions: o => o.ScrapeEndpointPath = "/metrics_from_AddPrometheusExporter");
+            configureOptions: o =>
+            {
+                o.ScrapeEndpointPath = "/metrics_from_AddPrometheusExporter";
+                o.DisableTimestamp = disableTimestamp;
+            });
     }
 
     [Fact]
@@ -407,7 +413,9 @@ private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
 
         if (!skipMetrics)
         {
-            await VerifyAsync(beginTimestamp, endTimestamp, response, requestOpenMetrics, meterTags);
+            var options = new PrometheusAspNetCoreOptions();
+            configureOptions?.Invoke(options);
+            await VerifyAsync(beginTimestamp, endTimestamp, response, requestOpenMetrics, meterTags, options.DisableTimestamp);
         }
         else
         {
@@ -419,7 +427,7 @@ private static async Task RunPrometheusExporterMiddlewareIntegrationTest(
         await host.StopAsync();
     }
 
-    private static async Task VerifyAsync(long beginTimestamp, long endTimestamp, HttpResponseMessage response, bool requestOpenMetrics, KeyValuePair<string, object?>[]? meterTags)
+    private static async Task VerifyAsync(long beginTimestamp, long endTimestamp, HttpResponseMessage response, bool requestOpenMetrics, KeyValuePair<string, object?>[]? meterTags, bool disableTimestamp = false)
     {
         Assert.Equal(HttpStatusCode.OK, response.StatusCode);
         Assert.True(response.Content.Headers.Contains("Last-Modified"));
@@ -439,6 +447,8 @@ private static async Task VerifyAsync(long beginTimestamp, long endTimestamp, Ht
 
         string content = (await response.Content.ReadAsStringAsync()).ReplaceLineEndings();
 
+        var timestampPart = disableTimestamp ? string.Empty : " (\\d+)";
+        var timestampPartOpenMetrics = disableTimestamp ? string.Empty : " (\\d+\\.\\d{3})";
         string expected = requestOpenMetrics
             ? $$"""
                     # TYPE target info
@@ -449,14 +459,14 @@ private static async Task VerifyAsync(long beginTimestamp, long endTimestamp, Ht
                     otel_scope_info{otel_scope_name="{{MeterName}}"} 1
                     # TYPE counter_double_bytes counter
                     # UNIT counter_double_bytes bytes
-                    counter_double_bytes_total{otel_scope_name="{{MeterName}}",otel_scope_version="{{MeterVersion}}",{{additionalTags}}key1="value1",key2="value2"} 101.17 (\d+\.\d{3})
+                    counter_double_bytes_total{otel_scope_name="{{MeterName}}",otel_scope_version="{{MeterVersion}}",{{additionalTags}}key1="value1",key2="value2"} 101.17{{timestampPartOpenMetrics}}
                     # EOF
 
                     """.ReplaceLineEndings()
             : $$"""
                     # TYPE counter_double_bytes_total counter
                     # UNIT counter_double_bytes_total bytes
-                    counter_double_bytes_total{otel_scope_name="{{MeterName}}",otel_scope_version="{{MeterVersion}}",{{additionalTags}}key1="value1",key2="value2"} 101.17 (\d+)
+                    counter_double_bytes_total{otel_scope_name="{{MeterName}}",otel_scope_version="{{MeterVersion}}",{{additionalTags}}key1="value1",key2="value2"} 101.17{{timestampPart}}
                     # EOF
 
                     """.ReplaceLineEndings();
@@ -465,9 +475,12 @@ private static async Task VerifyAsync(long beginTimestamp, long endTimestamp, Ht
 
         Assert.True(matches.Count == 1, content);
 
-        var timestamp = long.Parse(matches[0].Groups[1].Value.Replace(".", string.Empty, StringComparison.Ordinal), CultureInfo.InvariantCulture);
+        if (!disableTimestamp)
+        {
+            var timestamp = long.Parse(matches[0].Groups[1].Value.Replace(".", string.Empty, StringComparison.Ordinal), CultureInfo.InvariantCulture);
 
-        Assert.True(beginTimestamp <= timestamp && timestamp <= endTimestamp, $"{beginTimestamp} {timestamp} {endTimestamp}");
+            Assert.True(beginTimestamp <= timestamp && timestamp <= endTimestamp, $"{beginTimestamp} {timestamp} {endTimestamp}");
+        }
     }
 
     private static Task<IHost> StartTestHostAsync(

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

@@ -61,10 +61,12 @@ public void UriPrefixesInvalid()
         });
     }
 
-    [Fact]
-    public async Task PrometheusExporterHttpServerIntegration()
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task PrometheusExporterHttpServerIntegration(bool disableTimestamp)
     {
-        await RunPrometheusExporterHttpServerIntegrationTest();
+        await RunPrometheusExporterHttpServerIntegrationTest(disableTimestamp: disableTimestamp);
     }
 
     [Fact]
@@ -73,10 +75,12 @@ public async Task PrometheusExporterHttpServerIntegration_NoMetrics()
         await RunPrometheusExporterHttpServerIntegrationTest(skipMetrics: true);
     }
 
-    [Fact]
-    public async Task PrometheusExporterHttpServerIntegration_NoOpenMetrics()
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public async Task PrometheusExporterHttpServerIntegration_NoOpenMetrics(bool disableTimestamp)
     {
-        await RunPrometheusExporterHttpServerIntegrationTest(acceptHeader: string.Empty);
+        await RunPrometheusExporterHttpServerIntegrationTest(acceptHeader: string.Empty, disableTimestamp: disableTimestamp);
     }
 
     [Fact]
@@ -220,7 +224,7 @@ private static void TestPrometheusHttpListenerUriPrefixOptions(string[] uriPrefi
             });
     }
 
-    private static MeterProvider BuildMeterProvider(Meter meter, IEnumerable<KeyValuePair<string, object>> attributes, out string address)
+    private static MeterProvider BuildMeterProvider(Meter meter, IEnumerable<KeyValuePair<string, object>> attributes, out string address, bool disableTimestamp = false)
     {
         Random random = new Random();
         int retryAttempts = 5;
@@ -242,6 +246,7 @@ private static MeterProvider BuildMeterProvider(Meter meter, IEnumerable<KeyValu
                     .AddPrometheusHttpListener(options =>
                     {
                         options.UriPrefixes = [generatedAddress];
+                        options.DisableTimestamp = disableTimestamp;
                     })
                     .Build();
 
@@ -258,13 +263,13 @@ private static MeterProvider BuildMeterProvider(Meter meter, IEnumerable<KeyValu
         return provider ?? throw new InvalidOperationException("HttpListener could not be started");
     }
 
-    private static async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetrics = false, string acceptHeader = "application/openmetrics-text", KeyValuePair<string, object?>[]? meterTags = null)
+    private static async Task RunPrometheusExporterHttpServerIntegrationTest(bool skipMetrics = false, string acceptHeader = "application/openmetrics-text", KeyValuePair<string, object?>[]? meterTags = null, bool disableTimestamp = false)
     {
         var requestOpenMetrics = acceptHeader.StartsWith("application/openmetrics-text", StringComparison.Ordinal);
 
         using var meter = new Meter(MeterName, MeterVersion, meterTags);
 
-        var provider = BuildMeterProvider(meter, [], out var address);
+        var provider = BuildMeterProvider(meter, [], out var address, disableTimestamp);
 
         var counterTags = new KeyValuePair<string, object?>[]
         {
@@ -308,6 +313,8 @@ private static async Task RunPrometheusExporterHttpServerIntegrationTest(bool sk
 
             var content = await response.Content.ReadAsStringAsync();
 
+            var timestampPart = disableTimestamp ? string.Empty : " (\\d+)";
+            var timestampPartOpenMetrics = disableTimestamp ? string.Empty : " (\\d+\\.\\d{3})";
             var expected = requestOpenMetrics
                 ? "# TYPE target info\n"
                   + "# HELP target Target metadata\n"
@@ -317,11 +324,11 @@ private static async Task RunPrometheusExporterHttpServerIntegrationTest(bool sk
                   + $"otel_scope_info{{otel_scope_name='{MeterName}'}} 1\n"
                   + "# TYPE counter_double_bytes counter\n"
                   + "# UNIT counter_double_bytes bytes\n"
-                  + $"counter_double_bytes_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',{additionalTags}key1='value1',key2='value2'}} 101.17 (\\d+\\.\\d{{3}})\n"
+                  + $"counter_double_bytes_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',{additionalTags}key1='value1',key2='value2'}} 101.17{timestampPartOpenMetrics}\n"
                   + "# EOF\n"
                 : "# TYPE counter_double_bytes_total counter\n"
                   + "# UNIT counter_double_bytes_total bytes\n"
-                  + $"counter_double_bytes_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',{additionalTags}key1='value1',key2='value2'}} 101.17 (\\d+)\n"
+                  + $"counter_double_bytes_total{{otel_scope_name='{MeterName}',otel_scope_version='{MeterVersion}',{additionalTags}key1='value1',key2='value2'}} 101.17{timestampPart}\n"
                   + "# EOF\n";
 
             Assert.Matches(("^" + expected + "$").Replace('\'', '"'), content);