Working with prometheus now

open-telemetry · Nov 30, 2023 · 9526647 · 9526647
1 parent 74014ac
commit 9526647
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Showing 15 changed files with 259 additions and 168 deletions.
diff --git a/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/.publicApi/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/.publicApi/PublicAPI.Unshipped.txt
@@ -2,8 +2,8 @@ Microsoft.AspNetCore.Builder.PrometheusExporterApplicationBuilderExtensions
 Microsoft.AspNetCore.Builder.PrometheusExporterEndpointRouteBuilderExtensions
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.PrometheusAspNetCoreOptions() -> void
-OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.ScopeInfoEnabled.get -> bool
-OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.ScopeInfoEnabled.set -> void
+OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.OpenMetricsEnabled.get -> bool
+OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.OpenMetricsEnabled.set -> void
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.ScrapeEndpointPath.get -> string
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.ScrapeEndpointPath.set -> void
 OpenTelemetry.Exporter.PrometheusAspNetCoreOptions.ScrapeResponseCacheDurationMilliseconds.get -> int

diff --git a/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusAspNetCoreOptions.cs b/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusAspNetCoreOptions.cs
@@ -43,12 +43,12 @@ public int ScrapeResponseCacheDurationMilliseconds
     }
 
     /// <summary>
-    /// Gets or sets a value indicating whether to export metric scope info. Default value: true.
+    /// Gets or sets a value indicating whether to export OpenMetrics compatible scrape responses. Default value: true.
     /// </summary>
-    public bool ScopeInfoEnabled
+    public bool OpenMetricsEnabled
     {
-        get => this.ExporterOptions.ScopeInfoEnabled;
-        set => this.ExporterOptions.ScopeInfoEnabled = value;
+        get => this.ExporterOptions.OpenMetricsEnabled;
+        set => this.ExporterOptions.OpenMetricsEnabled = value;
     }
 
     internal PrometheusExporterOptions ExporterOptions { get; } = new();

diff --git a/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusExporterMiddleware.cs b/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusExporterMiddleware.cs
@@ -16,6 +16,8 @@
 
 using System.Diagnostics;
 using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+using Microsoft.Net.Http.Headers;
 using OpenTelemetry.Exporter.Prometheus;
 using OpenTelemetry.Internal;
 using OpenTelemetry.Metrics;
@@ -27,6 +29,8 @@ namespace OpenTelemetry.Exporter;
 /// </summary>
 internal sealed class PrometheusExporterMiddleware
 {
+    private const string OpenMetricsMediaType = "application/openmetrics-text";
+
     private readonly PrometheusExporter exporter;
 
     /// <summary>
@@ -75,7 +79,14 @@ public async Task InvokeAsync(HttpContext httpContext)
 #else
                     response.Headers.Add("Last-Modified", collectionResponse.GeneratedAtUtc.ToString("R"));
 #endif
-                    response.ContentType = "text/plain; charset=utf-8; version=0.0.4";
+                    if (this.exporter.OpenMetricsEnabled && this.AcceptsOpenMetrics(httpContext.Request))
+                    {
+                        response.ContentType = "application/openmetrics-text; version=1.0.0; charset=utf-8";
+                    }
+                    else
+                    {
+                        response.ContentType = "text/plain; charset=utf-8; version=0.0.4";
+                    }
 
                     await response.Body.WriteAsync(collectionResponse.View.Array, 0, collectionResponse.View.Count).ConfigureAwait(false);
                 }
@@ -102,4 +113,28 @@ public async Task InvokeAsync(HttpContext httpContext)
 
         this.exporter.OnExport = null;
     }
+
+    private bool AcceptsOpenMetrics(HttpRequest request)
+    {
+        var requestAccept = request.Headers[HeaderNames.Accept];
+
+        if (StringValues.IsNullOrEmpty(requestAccept))
+        {
+            return false;
+        }
+
+        var acceptTypes = requestAccept.ToString().Split(',');
+
+        foreach (var acceptType in acceptTypes)
+        {
+            var acceptSubType = acceptType.Split(';').FirstOrDefault()?.Trim();
+
+            if (acceptSubType == OpenMetricsMediaType)
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }
diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/.publicApi/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/.publicApi/PublicAPI.Unshipped.txt
@@ -1,4 +1,6 @@
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions
+OpenTelemetry.Exporter.PrometheusHttpListenerOptions.OpenMetricsEnabled.get -> bool
+OpenTelemetry.Exporter.PrometheusHttpListenerOptions.OpenMetricsEnabled.set -> void
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.UriPrefixes.get -> System.Collections.Generic.IReadOnlyCollection<string>
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.UriPrefixes.set -> void
 OpenTelemetry.Exporter.PrometheusHttpListenerOptions.PrometheusHttpListenerOptions() -> void

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs
@@ -184,7 +184,7 @@ private ExportResult OnCollect(Batch<Metric> metrics)
 
         try
         {
-            if (this.exporter.ScopeInfoEnabled)
+            if (this.exporter.OpenMetricsEnabled)
             {
                 this.scopes.Clear();
 
@@ -229,7 +229,7 @@ private ExportResult OnCollect(Batch<Metric> metrics)
                 {
                     try
                     {
-                        cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric), this.exporter.ScopeInfoEnabled);
+                        cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric), this.exporter.OpenMetricsEnabled);
                         break;
                     }
                     catch (IndexOutOfRangeException)

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs
@@ -38,7 +38,7 @@ public PrometheusExporter(PrometheusExporterOptions options)
         Guard.ThrowIfNull(options);
 
         this.ScrapeResponseCacheDurationMilliseconds = options.ScrapeResponseCacheDurationMilliseconds;
-        this.ScopeInfoEnabled = options.ScopeInfoEnabled;
+        this.OpenMetricsEnabled = options.OpenMetricsEnabled;
 
         this.CollectionManager = new PrometheusCollectionManager(this);
     }
@@ -64,7 +64,7 @@ internal Func<Batch<Metric>, ExportResult> OnExport
 
     internal int ScrapeResponseCacheDurationMilliseconds { get; }
 
-    internal bool ScopeInfoEnabled { get; }
+    internal bool OpenMetricsEnabled { 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
@@ -43,7 +43,7 @@ public int ScrapeResponseCacheDurationMilliseconds
     }
 
     /// <summary>
-    /// Gets or sets a value indicating whether to export metric scope info. Default value: true.
+    /// Gets or sets a value indicating whether to export OpenMetrics compatible scrape responses. Default value: true.
     /// </summary>
-    public bool ScopeInfoEnabled { get; set; } = true;
+    public bool OpenMetricsEnabled { get; set; } = true;
 }
diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs
@@ -18,6 +18,7 @@
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using OpenTelemetry.Internal;
+using OpenTelemetry.Metrics;
 
 namespace OpenTelemetry.Exporter.Prometheus;
 
@@ -347,7 +348,69 @@ public static int WriteScopeInfo(byte[] buffer, int cursor, string scopeName)
         buffer[cursor++] = unchecked((byte)' ');
         buffer[cursor++] = unchecked((byte)'1');
         buffer[cursor++] = ASCII_LINEFEED;
-        buffer[cursor++] = ASCII_LINEFEED;
+
+        return cursor;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int WriteTimestamp(byte[] buffer, int cursor, long value, bool openMetricsEnabled)
+    {
+        if (openMetricsEnabled)
+        {
+            cursor = WriteLong(buffer, cursor, value / 1000);
+            buffer[cursor++] = unchecked((byte)'.');
+
+            long millis = value % 1000;
+
+            if (millis < 100)
+            {
+                buffer[cursor++] = unchecked((byte)'0');
+            }
+
+            if (millis < 10)
+            {
+                buffer[cursor++] = unchecked((byte)'0');
+            }
+
+            return WriteLong(buffer, cursor, millis);
+        }
+
+        return WriteLong(buffer, cursor, value);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int WriteTags(byte[] buffer, int cursor, Metric metric, ReadOnlyTagCollection tags, bool openMetricsEnabled, bool writeEnclosingBraces = true)
+    {
+        if (tags.Count > 0 || openMetricsEnabled)
+        {
+            if (writeEnclosingBraces)
+            {
+                buffer[cursor++] = unchecked((byte)'{');
+            }
+
+            if (openMetricsEnabled)
+            {
+                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);
+                buffer[cursor++] = unchecked((byte)',');
+            }
+
+            if (writeEnclosingBraces)
+            {
+                buffer[cursor - 1] = unchecked((byte)'}'); // Note: We write the '}' over the last written comma, which is extra.
+            }
+        }
 
         return cursor;
     }