Azure Function中ILogger日志仅在Live Metrics，未同步到Transaction Search

问题详情 #

发布Azure Function后，已成功连接Application Insights：

• Transaction Search中能看到部分系统日志，但构造注入ILogger输出的自定义追踪日志缺失
• 这些自定义日志可正常显示在Live Metrics中
• 仅当将ILogger作为方法参数注入时，日志才会出现在Transaction Search中

注：为复用ILogger采用构造函数注入方式，代码中实际包含Startup配置（与最初计划的无Startup/IServiceCollection不符）。

代码片段 #

[assembly: FunctionsStartup(typeof(AFLeaderListFunc.Startup))]

namespace AFLeaderListFunc
{
    public class Startup : FunctionsStartup
    {
        public override void Configure(IFunctionsHostBuilder builder)
        {
            builder.Services.AddLogging();
            builder.Services.AddTransient<Function1>();
        }
    }
    public class Function1
    {
        private readonly ILogger _logger;

        public Function1(ILogger<Function1> logger)
        {
            _logger = logger;
        }


        [FunctionName("Function1")]
        public async Task Run([TimerTrigger("0 05 13 * * *")] TimerInfo myTimer)
        {
            try
            {
                _logger.LogInformation("Test using DI injection");
                _logger.LogInformation(await GetADUserAsyncByEmail());
                _logger.LogInformation("Executing complete");
                _logger.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
            }
            catch (Exception ex)
            {
                _logger.LogInformation(ex.ToString());
                Console.WriteLine(ex);
            }
        }
    }
}

.csproj配置 #

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  </PropertyGroup>

    <ItemGroup>
    <PackageReference Include="Azure.Identity" Version="1.8.1" />
    <PackageReference Include="Azure.Security.KeyVault.Secrets" Version="4.4.0" />
    <PackageReference Include="Dapper" Version="2.0.123" />
    <PackageReference Include="Microsoft.ApplicationInsights" Version="2.20.0" />
    <PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.15.0" />
    <PackageReference Include="Microsoft.AspNetCore.AzureKeyVault.HostingStartup" Version="2.0.4" />
    <PackageReference Include="Microsoft.Azure.Functions.Extensions" Version="1.1.0" />
    <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="3.1.32" />
    <PackageReference Include="Microsoft.Graph" Version="4.52.0" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.1.1" />
    <PackageReference Include="System.Data.SqlClient" Version="4.8.5" />
    <PackageReference Include="System.Text.Encodings.Web" Version="6.0.0" />
  </ItemGroup>
    <ItemGroup>
        <FunctionsPreservedDependencies Include="System.Text.Encodings.Web.dll" />
    </ItemGroup>
  <ItemGroup>
    <None Update="appsettings.json">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
    <None Update="host.json">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </None>
  </ItemGroup>
</Project>

核心原因分析 #

1. 上下文关联缺失：方法参数注入的ILogger会自动绑定当前Function执行的Operation ID，而构造注入的实例在初始化时未获取到该上下文，导致日志无法关联到Transaction追踪链，因此Transaction Search无法筛选到这些日志（Live Metrics不依赖严格上下文关联，所以能显示）。
2. 依赖包版本冲突：Microsoft.ApplicationInsights.WorkerService（2.15.0）与Microsoft.ApplicationInsights（2.20.0）版本差异过大，可能导致上下文传递逻辑异常。
3. 日志配置缺失：host.json未明确配置Application Insights的日志过滤规则，可能导致部分日志类别或级别被过滤。

排查与修复步骤 #

1. 手动绑定Operation ID到构造注入的ILogger #

注入IOperationIdProvider，为日志添加Operation ID标记，确保关联到Transaction追踪链：

private readonly ILogger _logger;
private readonly string _operationId;

public Function1(ILogger<Function1> logger, IOperationIdProvider operationIdProvider)
{
    _logger = logger;
    _operationId = operationIdProvider.GetOperationId();
}

// 日志输出时携带Operation ID
_logger.LogInformation("Test using DI injection {OperationId}", _operationId);

2. 统一Application Insights依赖包版本 #

将Microsoft.ApplicationInsights.WorkerService升级至与Microsoft.ApplicationInsights一致的版本（如2.20.0），避免版本冲突：

<PackageReference Include="Microsoft.ApplicationInsights" Version="2.20.0" />
<PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.20.0" />

3. 配置host.json日志规则 #

添加Application Insights日志配置，确保自定义日志被正确采集：

{
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      },
      "enableLiveMetricsFilters": true
    },
    "logLevel": {
      "AFLeaderListFunc.Function1": "Information",
      "Default": "Information"
    }
  }
}

4. 简化Startup配置 #

移除不必要的builder.Services.AddLogging()（Azure Functions宿主已默认配置日志系统）：

public override void Configure(IFunctionsHostBuilder builder)
{
    builder.Services.AddTransient<Function1>();
}

内容的提问来源于stack exchange，提问作者Alexander Thomsen