Modify output depending on accept headers

open-telemetry · Nov 30, 2023 · 937b7da · 937b7da
1 parent da28e9d
commit 937b7da
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Showing 8 changed files with 39 additions and 20 deletions.
diff --git a/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusExporterMiddleware.cs b/src/OpenTelemetry.Exporter.Prometheus.AspNetCore/PrometheusExporterMiddleware.cs
@@ -68,7 +68,11 @@ public async Task InvokeAsync(HttpContext httpContext)
 
         try
         {
-            var collectionResponse = await this.exporter.CollectionManager.EnterCollect().ConfigureAwait(false);
+            var openMetricsRequested =
+                this.exporter.OpenMetricsEnabled && this.AcceptsOpenMetrics(httpContext.Request);
+
+            var collectionResponse = await this.exporter.CollectionManager.EnterCollect(openMetricsRequested).ConfigureAwait(false);
+
             try
             {
                 if (collectionResponse.View.Count > 0)
@@ -79,7 +83,8 @@ public async Task InvokeAsync(HttpContext httpContext)
 #else
                     response.Headers.Add("Last-Modified", collectionResponse.GeneratedAtUtc.ToString("R"));
 #endif
-                    if (this.exporter.OpenMetricsEnabled && this.AcceptsOpenMetrics(httpContext.Request))
+
+                    if (openMetricsRequested)
                     {
                         response.ContentType = "application/openmetrics-text; version=1.0.0; charset=utf-8";
                     }

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusCollectionManager.cs
@@ -47,9 +47,9 @@ public PrometheusCollectionManager(PrometheusExporter exporter)
     }
 
 #if NET6_0_OR_GREATER
-    public ValueTask<CollectionResponse> EnterCollect()
+    public ValueTask<CollectionResponse> EnterCollect(bool openMetricsRequested)
 #else
-    public Task<CollectionResponse> EnterCollect()
+    public Task<CollectionResponse> EnterCollect(bool openMetricsRequested)
 #endif
     {
         this.EnterGlobalLock();
@@ -95,7 +95,7 @@ public Task<CollectionResponse> EnterCollect()
         this.ExitGlobalLock();
 
         CollectionResponse response;
-        var result = this.ExecuteCollect();
+        var result = this.ExecuteCollect(openMetricsRequested);
         if (result)
         {
             this.previousDataViewGeneratedAtUtc = DateTime.UtcNow;
@@ -170,11 +170,13 @@ private void WaitForReadersToComplete()
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private bool ExecuteCollect()
+    private bool ExecuteCollect(bool openMetricsRequested)
     {
         this.exporter.OnExport = this.onCollectRef;
+        this.exporter.OpenMetricsRequested = openMetricsRequested;
         var result = this.exporter.Collect(Timeout.Infinite);
         this.exporter.OnExport = null;
+        this.exporter.OpenMetricsRequested = null;
         return result;
     }
 
@@ -229,7 +231,14 @@ private ExportResult OnCollect(Batch<Metric> metrics)
                 {
                     try
                     {
-                        cursor = PrometheusSerializer.WriteMetric(this.buffer, cursor, metric, this.GetPrometheusMetric(metric), this.exporter.OpenMetricsEnabled);
+                        cursor = PrometheusSerializer.WriteMetric(
+                            this.buffer,
+                            cursor,
+                            metric,
+                            this.GetPrometheusMetric(metric),
+                            this.exporter.OpenMetricsEnabled,
+                            this.exporter.OpenMetricsRequested ?? false);
+
                         break;
                     }
                     catch (IndexOutOfRangeException)

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusExporter.cs
@@ -58,6 +58,8 @@ public PrometheusExporter(PrometheusExporterOptions options)
         set => this.funcExport = value;
     }
 
+    internal bool? OpenMetricsRequested { get; set; }
+
     internal Action OnDispose { get; set; }
 
     internal PrometheusCollectionManager CollectionManager { get; }

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusSerializer.cs
@@ -353,9 +353,9 @@ public static int WriteScopeInfo(byte[] buffer, int cursor, string scopeName)
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static int WriteTimestamp(byte[] buffer, int cursor, long value, bool openMetricsEnabled)
+    public static int WriteTimestamp(byte[] buffer, int cursor, long value, bool useOpenMetrics)
     {
-        if (openMetricsEnabled)
+        if (useOpenMetrics)
         {
             cursor = WriteLong(buffer, cursor, value / 1000);
             buffer[cursor++] = unchecked((byte)'.');

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, bool openMetricsEnabled = true)
+    public static int WriteMetric(byte[] buffer, int cursor, Metric metric, PrometheusMetric prometheusMetric, bool openMetricsEnabled = true, bool openMetricsRequested = false)
     {
         cursor = WriteTypeMetadata(buffer, cursor, prometheusMetric);
         cursor = WriteUnitMetadata(buffer, cursor, prometheusMetric);
@@ -81,7 +81,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
 
                 buffer[cursor++] = unchecked((byte)' ');
 
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsEnabled);
+                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
 
                 buffer[cursor++] = ASCII_LINEFEED;
             }
@@ -118,7 +118,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                     cursor = WriteLong(buffer, cursor, totalCount);
                     buffer[cursor++] = unchecked((byte)' ');
 
-                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsEnabled);
+                    cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
 
                     buffer[cursor++] = ASCII_LINEFEED;
                 }
@@ -133,7 +133,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 cursor = WriteDouble(buffer, cursor, metricPoint.GetHistogramSum());
                 buffer[cursor++] = unchecked((byte)' ');
 
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsEnabled);
+                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
 
                 buffer[cursor++] = ASCII_LINEFEED;
 
@@ -147,7 +147,7 @@ public static int WriteMetric(byte[] buffer, int cursor, Metric metric, Promethe
                 cursor = WriteLong(buffer, cursor, metricPoint.GetHistogramCount());
                 buffer[cursor++] = unchecked((byte)' ');
 
-                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsEnabled);
+                cursor = WriteTimestamp(buffer, cursor, timestamp, openMetricsRequested);
 
                 buffer[cursor++] = ASCII_LINEFEED;
             }

diff --git a/src/OpenTelemetry.Exporter.Prometheus.HttpListener/PrometheusHttpListener.cs b/src/OpenTelemetry.Exporter.Prometheus.HttpListener/PrometheusHttpListener.cs
@@ -151,7 +151,10 @@ private async Task ProcessRequestAsync(HttpListenerContext context)
     {
         try
         {
-            var collectionResponse = await this.exporter.CollectionManager.EnterCollect().ConfigureAwait(false);
+            var openMetricsRequested = this.exporter.OpenMetricsEnabled && this.AcceptsOpenMetrics(context.Request.Headers);
+
+            var collectionResponse = await this.exporter.CollectionManager.EnterCollect(openMetricsRequested).ConfigureAwait(false);
+
             try
             {
                 context.Response.Headers.Add("Server", string.Empty);
@@ -160,7 +163,7 @@ private async Task ProcessRequestAsync(HttpListenerContext context)
                     context.Response.StatusCode = 200;
                     context.Response.Headers.Add("Last-Modified", collectionResponse.GeneratedAtUtc.ToString("R"));
 
-                    if (this.AcceptsOpenMetrics(context.Request.Headers))
+                    if (openMetricsRequested)
                     {
                         context.Response.ContentType = "application/openmetrics-text; version=1.0.0; charset=utf-8";
                     }

diff --git a/.../OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusCollectionManagerTests.cs b/.../OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusCollectionManagerTests.cs
@@ -65,7 +65,7 @@ public async Task EnterExitCollectTest(int scrapeResponseCacheDurationMillisecon
             {
                 collectTasks[i] = Task.Run(async () =>
                 {
-                    var response = await exporter.CollectionManager.EnterCollect();
+                    var response = await exporter.CollectionManager.EnterCollect(false);
                     try
                     {
                         return new Response
@@ -98,7 +98,7 @@ public async Task EnterExitCollectTest(int scrapeResponseCacheDurationMillisecon
             counter.Add(100);
 
             // This should use the cache and ignore the second counter update.
-            var task = exporter.CollectionManager.EnterCollect();
+            var task = exporter.CollectionManager.EnterCollect(false);
             Assert.True(task.IsCompleted);
             var response = await task;
             try
@@ -129,7 +129,7 @@ public async Task EnterExitCollectTest(int scrapeResponseCacheDurationMillisecon
             {
                 collectTasks[i] = Task.Run(async () =>
                 {
-                    var response = await exporter.CollectionManager.EnterCollect();
+                    var response = await exporter.CollectionManager.EnterCollect(false);
                     try
                     {
                         return new Response

diff --git a/test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusSerializerTests.cs b/test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusSerializerTests.cs
@@ -601,6 +601,6 @@ public void HistogramOneDimensionWithScopeInfo()
 
     private static int WriteMetric(byte[] buffer, int cursor, Metric metric, bool useOpenMetrics = false)
     {
-        return PrometheusSerializer.WriteMetric(buffer, cursor, metric, PrometheusMetric.Create(metric), useOpenMetrics);
+        return PrometheusSerializer.WriteMetric(buffer, cursor, metric, PrometheusMetric.Create(metric), useOpenMetrics, useOpenMetrics);
     }
 }