[automated] Merge branch 'main' => 'dev'

Samples.sln

@@ -55,6 +55,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Compliance", "Compliance",
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "AuditReports", "src\Compliance\AuditReports\AuditReports.csproj", "{9B5FB8C7-27BA-4397-B4B8-DD0B0D525CB2}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LogSampling", "src\Telemetry\Logging\LogSampling\LogSampling.csproj", "{1A8652E7-EA1D-49AF-98B3-56D655F759B6}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -93,6 +95,10 @@ Global
 		{9B5FB8C7-27BA-4397-B4B8-DD0B0D525CB2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9B5FB8C7-27BA-4397-B4B8-DD0B0D525CB2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{9B5FB8C7-27BA-4397-B4B8-DD0B0D525CB2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1A8652E7-EA1D-49AF-98B3-56D655F759B6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1A8652E7-EA1D-49AF-98B3-56D655F759B6}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1A8652E7-EA1D-49AF-98B3-56D655F759B6}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1A8652E7-EA1D-49AF-98B3-56D655F759B6}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -116,6 +122,7 @@ Global
 		{931A6585-1085-4185-AE12-78BBA87F2A73} = {175F98E5-AFE8-4978-A512-EB84AD660208}
 		{C42F13CB-E8D9-4A37-BFCC-A50458509D69} = {301296EC-54FF-4ADC-B2D1-281E0C7F2867}
 		{9B5FB8C7-27BA-4397-B4B8-DD0B0D525CB2} = {C42F13CB-E8D9-4A37-BFCC-A50458509D69}
+		{1A8652E7-EA1D-49AF-98B3-56D655F759B6} = {248CB37C-2412-4231-96C0-092413C10D4B}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {6083D400-BF26-4ACE-86A8-778D26A8FA6A}

src/Telemetry/Logging/LogSampling/Log.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.Logging;
+
+namespace LogSampling;
+
+internal static partial class Log
+{
+    [LoggerMessage(Level = LogLevel.Error, Message = "ERROR log message in my application.")]
+    public static partial void ErrorMessage(ILogger logger);
+
+    [LoggerMessage(Level = LogLevel.Information, Message = "INFORMATION log message in my application.")]
+    public static partial void InformationMessage(ILogger logger);
+
+}

src/Telemetry/Logging/LogSampling/LogSampling.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <Description>Demonstrates how to use log sampling feature.</Description>
+    <OutputType>Exe</OutputType>
+    <NoWarn>$(NoWarn);EXTEXP0003</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="$(MicrosoftExtensionsLoggingConsoleVersion)" />
+    <PackageReference Include="Microsoft.Extensions.Telemetry" Version="9.4.0-preview.1.25174.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="appsettings.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

src/Telemetry/Logging/LogSampling/Program.cs

@@ -0,0 +1,41 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Threading;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace LogSampling;
+
+internal static class Program
+{
+    public static void Main()
+    {
+        var hostBuilder = Host.CreateApplicationBuilder();
+        hostBuilder.Logging.AddSimpleConsole(options =>
+        {
+            options.SingleLine = true;
+            options.TimestampFormat = "hh:mm:ss";
+        });
+
+        // Add the Random probabilistic sampler to the logging pipeline.
+        hostBuilder.Logging.AddRandomProbabilisticSampler(hostBuilder.Configuration);
+
+        var app = hostBuilder.Build();
+        var loggerFactory = app.Services.GetRequiredService<ILoggerFactory>();
+        var logger = loggerFactory.CreateLogger("SamplingDemo");
+
+        // Simulate a prod application with many log messages generated:
+        while (true)
+        {
+            Log.ErrorMessage(logger);
+
+            for (int i = 0; i < 10; i++)
+            {
+                Log.InformationMessage(logger);
+                Thread.Sleep(300);
+            }
+        }
+    }
+}

src/Telemetry/Logging/LogSampling/README.md

@@ -0,0 +1,20 @@
+# Log Sampling
+
+This sample shows how to use
+[log sampling](https://github.com/dotnet/extensions/blob/main/src/Libraries/Microsoft.Extensions.Telemetry/README.md).
+Log Sampling allows logs to be sampled, e.g. only some share of all log messages will be emitted.
+
+The sample uses a typical `HostApplicationBuilder` pattern to configure a small console application with
+logging. Log sampling is enabled by calling `.AddRandomProbabilisticSampler()` on the logging builder
+and
+providing a configuration via `appsettings.json`.
+
+The configuration in `appsettings.json` is flexible - you can configure specific sampling rates per
+any combination of
+- log level
+- category name
+- event id
+
+And, importantly, the configuration supports dynamic runtime updates via the `IOptionsMonitor<T>` pattern.
+So you can change the `appsettings.json` (in the `/artifacts/bin/LogSampling/Debug` folder) at runtime
+and the changes will be picked up by the Log sampling.

src/Telemetry/Logging/LogSampling/appsettings.json

@@ -0,0 +1,20 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information"
+    }
+  },
+
+  "RandomProbabilisticSampler": {
+    "Rules": [
+      {
+        "LogLevel": "Information",
+        "Probability": 1
+      },
+      {
+        "LogLevel": "Error",
+        "Probability": 1
+      }
+    ]
+  }
+}