.NET 7 Azure Function中ITelemetryInitializer无法添加日志自定义属性

问题分析 #

你当前使用的是隔离进程模型的Azure Functions（由ConfigureFunctionsWorkerDefaults标识），这种模型下传统的ITelemetryInitializer注册逻辑需要调整，同时你的包引用存在冗余，这些都是导致自定义属性未生效的核心原因。

修复步骤 #

1. 清理冗余包引用 #

移除不需要的ASP.NET Core和基础Application Insights包，仅保留Worker Service专用包：

<PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.21.0"/>
<!-- 移除Microsoft.ApplicationInsights和Microsoft.ApplicationInsights.AspNetCore -->

2. 调整Program.cs中的服务注册逻辑 #

确保正确启用Application Insights Worker Service，并注册自定义初始化器，同时配置日志关联：

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults()
    .ConfigureServices((hostContext, services) =>
    {
        // 启用Application Insights Worker Service核心功能
        services.AddApplicationInsightsTelemetryWorkerService();
        // 注册自定义Telemetry初始化器
        services.AddSingleton<ITelemetryInitializer, CustomTelemetry>();
        // 确保Application Insights日志接收器生效
        services.Configure<LoggerFilterOptions>(options =>
        {
            var aiLoggerRule = options.Rules.FirstOrDefault(r => 
                r.ProviderName == "Microsoft.Extensions.Logging.ApplicationInsights.ApplicationInsightsLoggerProvider");
            if (aiLoggerRule != null)
            {
                aiLoggerRule.LogLevel = LogLevel.Information; // 根据需求调整日志级别
            }
        });
    })
    .Build();

host.Run();

3. 完善自定义Telemetry初始化器 #

添加属性存在性检查，避免重复添加报错：

using Microsoft.ApplicationInsights.Channel;
using Microsoft.ApplicationInsights.Extensibility;

public class CustomTelemetry : ITelemetryInitializer
{
    public void Initialize(ITelemetry telemetry)
    {
        if (!telemetry.Context.GlobalProperties.ContainsKey("GlobalProperties"))
        {
            telemetry.Context.GlobalProperties["GlobalProperties"] = "test";
        }
    }
}

4. 验证日志输出方式 #

确保函数中使用ILogger进行日志记录（而非直接操作TelemetryClient）：

public class SampleFunction
{
    private readonly ILogger<SampleFunction> _logger;

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

    [Function("SampleFunction")]
    public async Task<IActionResult> Run([HttpTrigger(AuthorizationLevel.Function, "get")] HttpRequest req)
    {
        _logger.LogInformation("Function executed successfully");
        return new OkObjectResult("Completed");
    }
}

验证方式 #

在Application Insights的日志查询中，通过customDimensions.GlobalProperties即可查看自定义属性值，例如：

traces
| where customDimensions.GlobalProperties == "test"

内容的提问来源于stack exchange，提问作者James