.NET 8独立进程Azure Functions集成Serilog后AI日志重复问题

问题 #

我有一个基于.NET 8的独立工作进程Azure Functions项目，已集成ASP.NET Core。为记录范围属性，我希望使用Serilog及Application Insights接收器。

本地配置中已定义APPINSIGHTS_INSTRUMENTATIONKEY和APPLICATIONINSIGHTS_CONNECTION_STRING，Program.cs代码如下：

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication(worker => {})
    .ConfigureAppConfiguration((hostingContext, configBuilder) =>
    {
        configBuilder.AddJsonFile("local.settings.json", optional: true, reloadOnChange: true);
    })
    .ConfigureServices((hostBuilderContext, services) =>
    {
        services.AddApplicationInsightsTelemetryWorkerService();
        services.ConfigureFunctionsApplicationInsights();
    })
    .UseSerilog((context, provider, configuration) =>
    {
        var telemetryClient = provider.GetRequiredService<TelemetryClient>();
       
        configuration
            .Enrich.WithMachineName()
            .Enrich.WithEnvironmentName()
            .Enrich.FromLogContext()
            .WriteTo.ApplicationInsights(telemetryClient, TelemetryConverter.Traces)
            .WriteTo.Console();
    })
    .Build();

await host.RunAsync();

host.json配置如下：

{
    "version": "2.0",
    "extensions": {
        "durableTask": {
            "storageProvider": {
                "type": "mssql",
                "connectionStringName": "EnterpriseResourcePlanningServicesDbConnection",
                "taskEventLockTimeout": "00:02:00",
                "createDatabaseIfNotExists": true,
                "schemaName": "dt"
            }
        }
    }
}

本地运行时出现日志重复：一条带[INF]标识的日志在customDimensions中无范围数据，另一条则包含完整的范围属性。尝试清除HostBuilder的ConfigureLogging提供程序但无效，请问问题原因及解决方法？

重复日志示例：

问题原因 #

1. 双重日志管道冲突：同时启用了两个向Application Insights写入日志的路径：
   • 一是通过services.AddApplicationInsightsTelemetryWorkerService()和services.ConfigureFunctionsApplicationInsights()注册的Azure Functions默认日志提供程序，它会自动发送日志到AI，但不会处理Serilog的LogContext范围属性；
   • 二是Serilog的WriteTo.ApplicationInsights接收器，它会携带LogContext中的范围属性，但和默认管道形成重复输出。
2. 默认日志提供程序未彻底移除：仅清除ConfigureLogging的提供程序不足以禁用Azure Functions独立工作进程自动注册的内置日志提供程序，需要显式处理。

解决方法 #

方案1：禁用默认AI日志提供程序，仅保留Serilog管道 #

修改Program.cs，调整服务注册逻辑，彻底移除默认日志提供程序：

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication(worker => {})
    .ConfigureAppConfiguration((hostingContext, configBuilder) =>
    {
        configBuilder.AddJsonFile("local.settings.json", optional: true, reloadOnChange: true);
    })
    .ConfigureServices((hostBuilderContext, services) =>
    {
        // 注册Application Insights核心服务，禁用默认日志相关配置
        services.AddApplicationInsightsTelemetryWorkerService(options =>
        {
            options.EnableAdaptiveSampling = true;
        });
        // 移除所有默认日志提供程序，避免冲突
        services.RemoveAll<ILoggerProvider>();
    })
    .UseSerilog((context, provider, configuration) =>
    {
        var telemetryClient = provider.GetRequiredService<TelemetryClient>();
       
        configuration
            .Enrich.WithMachineName()
            .Enrich.WithEnvironmentName()
            .Enrich.FromLogContext()
            .WriteTo.ApplicationInsights(telemetryClient, TelemetryConverter.Events) // 可选：用Events替代Traces，避免格式冲突
            .WriteTo.Console();
    })
    .Build();

await host.RunAsync();

方案2：让默认日志系统使用Serilog作为底层提供程序 #

统一日志管道，让Azure Functions默认日志流程基于Serilog运行：

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication(worker => {})
    .ConfigureAppConfiguration((hostingContext, configBuilder) =>
    {
        configBuilder.AddJsonFile("local.settings.json", optional: true, reloadOnChange: true);
    })
    .ConfigureLogging((context, logging) =>
    {
        // 清除所有默认日志提供程序
        logging.ClearProviders();
        // 添加Serilog作为唯一日志提供程序
        logging.AddSerilog(dispose: true);
    })
    .ConfigureServices((hostBuilderContext, services) =>
    {
        services.AddApplicationInsightsTelemetryWorkerService();
        services.ConfigureFunctionsApplicationInsights();
    })
    .UseSerilog((context, provider, configuration) =>
    {
        configuration
            .Enrich.WithMachineName()
            .Enrich.WithEnvironmentName()
            .Enrich.FromLogContext()
            .WriteTo.ApplicationInsights(provider.GetRequiredService<TelemetryClient>(), TelemetryConverter.Traces)
            .WriteTo.Console();
    })
    .Build();

await host.RunAsync();

额外优化：配置host.json精简日志输出 #

在host.json中添加日志级别配置，减少冗余日志：

{
    "version": "2.0",
    "logging": {
        "logLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        },
        "applicationInsights": {
            "enableDependencyTracking": true,
            "enablePerformanceCountersCollection": true,
            "enableLiveMetrics": true,
            "disableTelemetry": false
        }
    },
    "extensions": {
        "durableTask": {
            "storageProvider": {
                "type": "mssql",
                "connectionStringName": "EnterpriseResourcePlanningServicesDbConnection",
                "taskEventLockTimeout": "00:02:00",
                "createDatabaseIfNotExists": true,
                "schemaName": "dt"
            }
        }
    }
}

内容的提问来源于stack exchange，提问作者321X