[AzureMonitorExporter] Add ApplicationInsightsSampler to the exporter (Azure#36972)

rajkumar-rangaraj · web-flow · commit 1cfd94f97a84 · 2023-06-14T22:47:36.000Z
* Add `ApplicationInsightsSampler` to the exporter

* Changelog + public Api

* IDeferredTracerProviderBuilder
diff --git a/eng/Packages.Data.props b/eng/Packages.Data.props
@@ -122,7 +122,6 @@
     <!-- OpenTelemetry dependency approved for Azure.Monitor.OpenTelemetry.Exporter package only -->
     <PackageReference Update="OpenTelemetry" Version="1.4.0" />
     <PackageReference Update="OpenTelemetry.Exporter.InMemory" Version="1.4.0" />
-    <PackageReference Update="OpenTelemetry.Extensions.AzureMonitor" Version="1.0.0-beta.4" />
     <PackageReference Update="OpenTelemetry.Extensions.Hosting" Version="1.4.0" />
     <PackageReference Update="OpenTelemetry.Instrumentation.AspNetCore" Version="1.0.0-rc9.14" />
     <PackageReference Update="OpenTelemetry.Instrumentation.Http" Version="1.0.0-rc9.14" />
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/CHANGELOG.md b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/CHANGELOG.md
@@ -4,12 +4,18 @@
 
 ### Features Added
 
+* Added `SamplingRatio` property to customize the sampling rate in Azure Monitor Exporter.
+  ([#36972](https://github.com/Azure/azure-sdk-for-net/pull/36972))
+
 ### Breaking Changes
 
 ### Bugs Fixed
 
 ### Other Changes
 
+* Removed reference to `OpenTelemetry.Extensions.AzureMonitor`.
+  ([#36972](https://github.com/Azure/azure-sdk-for-net/pull/36972))
+
 ## 1.0.0-beta.4 (2023-05-09)
 
 ### Features Added
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/README.md b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/README.md
@@ -18,7 +18,6 @@ The Azure Monitor Distro is a distribution of the .NET OpenTelemetry SDK and rel
   * [ASP.NET Core Instrumentation Library](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.AspNetCore/) provides automatic tracing for incoming HTTP requests to ASP.NET Core applications.
   * [HTTP Client Instrumentation Library](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.Http/) provides automatic tracing for outgoing HTTP requests made using [System.Net.Http.HttpClient](https://docs.microsoft.com/dotnet/api/system.net.http.httpclient) and [System.Net.HttpWebRequest](https://docs.microsoft.com/dotnet/api/system.net.httpwebrequest).
   * [SQL Client Instrumentation Library](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.SqlClient) provides automatic tracing for SQL queries executed using the [Microsoft.Data.SqlClient](https://www.nuget.org/packages/Microsoft.Data.SqlClient) and [System.Data.SqlClient](https://www.nuget.org/packages/System.Data.SqlClient) packages.
-  * [Application Insights Sampler](https://www.nuget.org/packages/OpenTelemetry.Extensions.AzureMonitor/) provides a sampling that is compatible with Application Insights sampling.
 
 * Metrics
   * [ASP.NET Core Instrumentation Library](https://www.nuget.org/packages/OpenTelemetry.Instrumentation.AspNetCore/) provides automatic collection of common ASP.NET Core metrics.
@@ -152,8 +151,10 @@ builder.Services.Configure<SqlClientInstrumentationOptions>(options =>
 When using the Azure Monitor Distro, the sampling percentage for telemetry data is set to 100% (1.0F) by default. For example, let's say you want to set the sampling percentage to 50%. You can achieve this by modifying the code as follows:
 
 ``` C#
-builder.Services.AddOpenTelemetry().UseAzureMonitor();
-builder.Services.Configure<ApplicationInsightsSamplerOptions>(options => { options.SamplingRatio = 0.5F; });
+builder.Services.AddOpenTelemetry().UseAzureMonitor(o =>
+{
+    o.SamplingRatio = 0.5F;
+});
 ```
 
 #### Adding Custom ActivitySource to Traces
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/api/Azure.Monitor.OpenTelemetry.AspNetCore.netstandard2.0.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/api/Azure.Monitor.OpenTelemetry.AspNetCore.netstandard2.0.cs
@@ -6,6 +6,7 @@ public AzureMonitorOptions() { }
         public string ConnectionString { get { throw null; } set { } }
         public Azure.Core.TokenCredential Credential { get { throw null; } set { } }
         public bool DisableOfflineStorage { get { throw null; } set { } }
+        public float SamplingRatio { get { throw null; } set { } }
         public string StorageDirectory { get { throw null; } set { } }
     }
     public static partial class OpenTelemetryBuilderExtensions
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/Azure.Monitor.OpenTelemetry.AspNetCore.csproj b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/Azure.Monitor.OpenTelemetry.AspNetCore.csproj
@@ -9,7 +9,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="OpenTelemetry.Extensions.AzureMonitor" />
     <PackageReference Include="OpenTelemetry.Extensions.Hosting" />
     <PackageReference Include="OpenTelemetry.Instrumentation.AspNetCore" />
     <PackageReference Include="OpenTelemetry.Instrumentation.Http" />
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/AzureMonitorOptions.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/AzureMonitorOptions.cs
@@ -36,6 +36,13 @@ public class AzureMonitorOptions : ClientOptions
         /// </summary>
         public bool DisableOfflineStorage { get; set; }
 
+        /// <summary>
+        /// Gets or sets the ratio of telemetry items to be sampled. The value must be between 0.0F and 1.0F, inclusive.
+        /// For example, specifying 0.4 means that 40% of traces are sampled and 60% are dropped.
+        /// The default value is 1.0F, indicating that all telemetry items are sampled.
+        /// </summary>
+        public float SamplingRatio { get; set; } = 1.0F;
+
         /// <summary>
         /// Override the default directory for offline storage.
         /// </summary>
@@ -46,6 +53,7 @@ internal void SetValueToExporterOptions(AzureMonitorExporterOptions exporterOpti
             exporterOptions.ConnectionString = ConnectionString;
             exporterOptions.Credential = Credential;
             exporterOptions.DisableOfflineStorage = DisableOfflineStorage;
+            exporterOptions.SamplingRatio = SamplingRatio;
             exporterOptions.StorageDirectory = StorageDirectory;
             if (Transport != null)
             {
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/OpenTelemetryBuilderExtensions.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.AspNetCore/src/OpenTelemetryBuilderExtensions.cs
@@ -8,7 +8,6 @@
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using OpenTelemetry;
-using OpenTelemetry.Extensions.AzureMonitor;
 using OpenTelemetry.Logs;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
@@ -94,11 +93,6 @@ public static OpenTelemetryBuilder UseAzureMonitor(this OpenTelemetryBuilder bui
                             .AddAspNetCoreInstrumentation()
                             .AddHttpClientInstrumentation()
                             .AddSqlClientInstrumentation()
-                            .SetSampler(sp =>
-                            {
-                                var options = sp.GetRequiredService<IOptionsMonitor<ApplicationInsightsSamplerOptions>>().Get(Options.DefaultName);
-                                return new ApplicationInsightsSampler(options);
-                            })
                             .AddAzureMonitorTraceExporter());
 
             builder.WithMetrics(b => b
@@ -116,9 +110,6 @@ public static OpenTelemetryBuilder UseAzureMonitor(this OpenTelemetryBuilder bui
                 });
             });
 
-            // Set the default sampling ratio to 100 % to ensure that all telemetry is captured by default.
-            builder.Services.Configure<ApplicationInsightsSamplerOptions>(options => { options.SamplingRatio = 1.0F; });
-
             // Add AzureMonitorLogExporter to AzureMonitorOptions
             // once the service provider is available containing the final
             // AzureMonitorOptions.
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/CHANGELOG.md b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/CHANGELOG.md
@@ -4,6 +4,9 @@
 
 ### Features Added
 
+* Added `ApplicationInsightsSampler` to the exporter, enabling users to customize the sampling rate using the `SamplingRatio` property.
+  ([#36972](https://github.com/Azure/azure-sdk-for-net/pull/36972))
+
 ### Breaking Changes
 
 ### Bugs Fixed
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/api/Azure.Monitor.OpenTelemetry.Exporter.netstandard2.0.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/api/Azure.Monitor.OpenTelemetry.Exporter.netstandard2.0.cs
@@ -15,6 +15,7 @@ public AzureMonitorExporterOptions(Azure.Monitor.OpenTelemetry.Exporter.AzureMon
         public string? ConnectionString { get { throw null; } set { } }
         public Azure.Core.TokenCredential? Credential { get { throw null; } set { } }
         public bool DisableOfflineStorage { get { throw null; } set { } }
+        public float SamplingRatio { get { throw null; } set { } }
         public string? StorageDirectory { get { throw null; } set { } }
         public Azure.Monitor.OpenTelemetry.Exporter.AzureMonitorExporterOptions.ServiceVersion Version { get { throw null; } set { } }
         public enum ServiceVersion
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterOptions.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterOptions.cs
@@ -30,6 +30,13 @@ public class AzureMonitorExporterOptions : ClientOptions
         /// </summary>
         public TokenCredential? Credential { get; set; }
 
+        /// <summary>
+        /// Gets or sets the ratio of telemetry items to be sampled. The value must be between 0.0F and 1.0F, inclusive.
+        /// For example, specifying 0.4 means that 40% of traces are sampled and 60% are dropped.
+        /// The default value is 1.0F, indicating that all telemetry items are sampled.
+        /// </summary>
+        public float SamplingRatio { get; set; } = 1.0F;
+
         /// <summary>
         /// The <see cref="ServiceVersion"/> of the Azure Monitor ingestion API.
         /// </summary>
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterTraceExtensions.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/AzureMonitorExporterTraceExtensions.cs
@@ -49,10 +49,15 @@ public static TracerProviderBuilder AddAzureMonitorTraceExporter(
                 builder.ConfigureServices(services => services.Configure(finalOptionsName, configure));
             }
 
-            return builder.AddProcessor(sp =>
+            var deferredBuilder = builder as IDeferredTracerProviderBuilder;
+            if (deferredBuilder == null)
             {
-                var exporterOptions = sp.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(finalOptionsName);
+                throw new InvalidOperationException("The provided TracerProviderBuilder does not implement IDeferredTracerProviderBuilder.");
+            }
 
+            return deferredBuilder.Configure((sp, builder) =>
+            {
+                var exporterOptions = sp.GetRequiredService<IOptionsMonitor<AzureMonitorExporterOptions>>().Get(finalOptionsName);
                 if (name == null && configure != null)
                 {
                     // If we are NOT using named options, we execute the
@@ -63,18 +68,20 @@ public static TracerProviderBuilder AddAzureMonitorTraceExporter(
                     configure(exporterOptions);
                 }
 
+                builder.SetSampler(new ApplicationInsightsSampler(exporterOptions.SamplingRatio));
+
                 if (credential != null)
                 {
                     // Credential can be set by either AzureMonitorExporterOptions or Extension Method Parameter.
                     // Options should take precedence.
                     exporterOptions.Credential ??= credential;
                 }
 
-                return new CompositeProcessor<Activity>(new BaseProcessor<Activity>[]
+                builder.AddProcessor(new CompositeProcessor<Activity>(new BaseProcessor<Activity>[]
                 {
                     new StandardMetricsExtractionProcessor(new AzureMonitorMetricExporter(exporterOptions)),
                     new BatchActivityExportProcessor(new AzureMonitorTraceExporter(exporterOptions))
-                });
+                }));
             });
         }
     }
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/Internals/ApplicationInsightsSampler.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/src/Internals/ApplicationInsightsSampler.cs
@@ -0,0 +1,103 @@
+﻿// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using OpenTelemetry.Trace;
+
+namespace Azure.Monitor.OpenTelemetry.Exporter.Internals;
+
+/// <summary>
+/// Sample configurable for OpenTelemetry exporters for compatibility
+/// with Application Insight SDKs.
+/// </summary>
+internal class ApplicationInsightsSampler : Sampler
+{
+    private static readonly SamplingResult RecordOnlySamplingResult = new(SamplingDecision.RecordOnly);
+    private readonly SamplingResult recordAndSampleSamplingResult;
+    private readonly float samplingRatio;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ApplicationInsightsSampler"/> class.
+    /// </summary>
+    /// <param name="samplingRatio">
+    /// Ratio of telemetry that should be sampled.
+    /// For example; Specifying 0.4F means 40% of traces are sampled and 60% are dropped.
+    /// </param>
+    public ApplicationInsightsSampler(float samplingRatio)
+    {
+        // Ensure passed ratio is between 0 and 1, inclusive
+        if (samplingRatio < 0.0F || samplingRatio > 1.0F)
+        {
+            throw new ArgumentOutOfRangeException(nameof(samplingRatio), "Sampling ratio must be between 0.0 and 1.0 (inclusive).");
+        }
+
+        this.samplingRatio = samplingRatio;
+        Description = "ApplicationInsightsSampler{" + samplingRatio + "}";
+        var sampleRate = (float)Math.Round(samplingRatio * 100);
+        recordAndSampleSamplingResult = new SamplingResult(
+            SamplingDecision.RecordAndSample,
+            new Dictionary<string, object>
+                {
+                    { "sampleRate", sampleRate },
+                });
+    }
+
+    /// <summary>
+    /// Computational method using the DJB2 Hash algorithm to decide whether to sample
+    /// a given telemetry item, based on its Trace Id.
+    /// </summary>
+    /// <param name="samplingParameters">Parameters of telemetry item used to make sampling decision.</param>
+    /// <returns>Returns whether or not we should sample telemetry in the form of a <see cref="SamplingResult"/> class.</returns>
+    public override SamplingResult ShouldSample(in SamplingParameters samplingParameters)
+    {
+        if (samplingRatio == 0)
+        {
+            return RecordOnlySamplingResult;
+        }
+
+        if (samplingRatio == 1)
+        {
+            return recordAndSampleSamplingResult;
+        }
+
+        double sampleScore = DJB2SampleScore(samplingParameters.TraceId.ToHexString().ToUpperInvariant());
+
+        if (sampleScore < samplingRatio)
+        {
+            return recordAndSampleSamplingResult;
+        }
+        else
+        {
+            return RecordOnlySamplingResult;
+        }
+    }
+
+    private static double DJB2SampleScore(string traceIdHex)
+    {
+        // Calculate DJB2 hash code from hex-converted TraceId
+        int hash = 5381;
+
+        for (int i = 0; i < traceIdHex.Length; i++)
+        {
+            unchecked
+            {
+                hash = (hash << 5) + hash + (int)traceIdHex[i];
+            }
+        }
+
+        // Take the absolute value of the hash
+        if (hash == int.MinValue)
+        {
+            hash = int.MaxValue;
+        }
+        else
+        {
+            hash = Math.Abs(hash);
+        }
+
+        // Divide by MaxValue for value between 0 and 1 for sampling score
+        double samplingScore = (double)hash / int.MaxValue;
+        return samplingScore;
+    }
+}
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Demo/Azure.Monitor.OpenTelemetry.Exporter.Demo.csproj b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Demo/Azure.Monitor.OpenTelemetry.Exporter.Demo.csproj
@@ -14,7 +14,6 @@
   <ItemGroup>
     <PackageReference Include="Azure.Identity" VersionOverride="1.8.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" VersionOverride="6.0.0" />
-    <PackageReference Include="OpenTelemetry.Extensions.AzureMonitor" />
     <ProjectReference Include="..\..\src\Azure.Monitor.OpenTelemetry.Exporter.csproj" />
   </ItemGroup>
 
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Demo/Traces/TraceDemo.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Demo/Traces/TraceDemo.cs
@@ -6,7 +6,6 @@
 using System.Diagnostics;
 using Azure.Core;
 using OpenTelemetry;
-using OpenTelemetry.Extensions.AzureMonitor;
 using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
 
@@ -36,8 +35,7 @@ public TraceDemo(string connectionString, TokenCredential? credential = null)
                             .AddSource(ActivitySourceName)
                             .AddProcessor(new ActivityFilteringProcessor())
                             .AddProcessor(new ActivityEnrichingProcessor())
-                            .SetSampler(new ApplicationInsightsSampler(new ApplicationInsightsSamplerOptions() { SamplingRatio = 1.0F }))
-                            .AddAzureMonitorTraceExporter(o => o.ConnectionString = connectionString, credential)
+                            .AddAzureMonitorTraceExporter(o => { o.ConnectionString = connectionString; o.SamplingRatio = 1.0F; }, credential)
                             .Build();
         }
 
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/ApplicationInsightsSamplerTests.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/ApplicationInsightsSamplerTests.cs
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/Azure.Monitor.OpenTelemetry.Exporter.Tests.csproj b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/Azure.Monitor.OpenTelemetry.Exporter.Tests.csproj
diff --git a/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/SampleRateTests.cs b/sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/tests/Azure.Monitor.OpenTelemetry.Exporter.Tests/SampleRateTests.cs

Original file line number	Diff line number	Diff line change
`@@ -6,6 +6,7 @@ public AzureMonitorOptions() { }`
`6`	`6`	`public string ConnectionString { get { throw null; } set { } }`
`7`	`7`	`public Azure.Core.TokenCredential Credential { get { throw null; } set { } }`
`8`	`8`	`public bool DisableOfflineStorage { get { throw null; } set { } }`
	`9`	`+ public float SamplingRatio { get { throw null; } set { } }`
`9`	`10`	`public string StorageDirectory { get { throw null; } set { } }`
`10`	`11`	`}`
`11`	`12`	`public static partial class OpenTelemetryBuilderExtensions`