.NET 8 ASP.NET应用实现OpenTelemetry日志/指标/追踪JSON控制台输出

核心问题原因 #

你的普通日志通过自定义JsonLogFormatter实现了JSON格式，但OpenTelemetry的追踪（Tracing）、指标（Metrics）使用独立的Console Exporter，默认输出为文本格式，需要单独配置JSON格式化规则。

分步解决方案 #

1. 安装必要NuGet包 #

确保项目已安装OpenTelemetry控制台导出器包：

dotnet add package OpenTelemetry.Exporter.Console

2. 配置追踪（Tracing）为JSON输出 #

修改OpenTelemetry追踪配置，为控制台导出器指定JSON格式化器：

otel.WithTracing(tracing =>
{
    tracing.AddAspNetCoreInstrumentation();
    tracing.AddHttpClientInstrumentation();
    // 启用JSON格式输出
    tracing.AddConsoleExporter(options =>
    {
        options.Formatter = new JsonConsoleExporterFormatter();
    });
});

3. 配置指标（Metrics）为JSON输出 #

为Metrics模块添加控制台导出器并启用JSON格式：

otel.WithMetrics(metrics => metrics
    .AddAspNetCoreInstrumentation()
    .AddMeter("Microsoft.AspNetCore.Hosting")
    .AddMeter("Microsoft.AspNetCore.Server.Kestrel")
    // 添加JSON格式的指标导出
    .AddConsoleExporter(options =>
    {
        options.Formatter = new JsonConsoleExporterFormatter();
    })
);

4. 统一OpenTelemetry日志的JSON格式 #

如果应用通过OpenTelemetry Logger Provider输出日志，可将其关联到已配置的LoggerFactory，或直接配置JSON导出：

otel.WithLogging(logging =>
{
    // 复用已有的JSON日志格式化配置
    logging.SetLoggerFactory(loggerFactory);
    // 也可直接指定JSON导出器
    // logging.AddConsoleExporter(options => options.Formatter = new JsonConsoleExporterFormatter());
});

完整修改后代码示例 #

var builder = WebApplication.CreateBuilder(args);
var services = builder.Services;
var configuration = builder.Configuration;

// OpenTelemetry核心配置
var otel = services.AddOpenTelemetry();

// Metrics配置：JSON格式控制台导出
otel.WithMetrics(metrics => metrics
    .AddAspNetCoreInstrumentation()
    .AddMeter("Microsoft.AspNetCore.Hosting")
    .AddMeter("Microsoft.AspNetCore.Server.Kestrel")
    .AddConsoleExporter(options =>
    {
        options.Formatter = new JsonConsoleExporterFormatter();
    })
);

// Tracing配置：JSON格式控制台导出
otel.WithTracing(tracing =>
{
    tracing.AddAspNetCoreInstrumentation();
    tracing.AddHttpClientInstrumentation();
    tracing.AddConsoleExporter(options =>
    {
        options.Formatter = new JsonConsoleExporterFormatter();
    });
});

// Logging配置：统一JSON格式
otel.WithLogging(logging =>
{
    logging.SetLoggerFactory(loggerFactory);
});

// 原有自定义JSON日志格式化配置
var loggerFactory = LoggerFactory.Create(builder =>
{
    builder.ClearProviders();
    builder.AddConfiguration(configuration.GetSection("Logging"))
        .AddConsole();
    builder.AddConsoleFormatter<JsonLogFormatter, JsonLogOptions>();
});
services.AddSingleton(loggerFactory);
services.AddLogging();

var app = builder.Build();
// 后续应用中间件配置...

效果验证 #

修改完成后，OpenTelemetry的追踪、指标、日志都会以JSON格式输出到控制台，示例输出如下：

{"ActivityId":"8794488a000a8aa943fb4bd76b8becbe","SpanId":"bae785686698f263","TraceFlags":"Recorded","SourceName":"System.Net.Http","DisplayName":"GET","Kind":"Client",...}
{"Name":"http.server.request.duration","Labels":{"http.method":"GET","http.route":"/api/values"},"Value":123.45,"Timestamp":"2024-03-14T19:38:23.2569003+01:00",...}

内容的提问来源于stack exchange，提问作者user1713059