.net core 结构化日志组件Serilog：记录对查询分析友好的日志

• .net core 结构化日志组件Serilog：记录对查询分析友好的日志
  • 结构化日志的好处
  • 场景举例
  • 内容实践

结构化日志的好处

• 易于检索
• 易于分析统计

场景举例

• 实现日志警告
• 实现上下文的关联
• 实现与追踪系统集成

内容实践

安装相关依赖包

https://www.nuget.org/packages/Serilog.AspNetCore

配置日志级别 appsetting.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Information",
        "System": "Information"
      }
    }
  },
  "AllowedHosts": "*"
}

Program.cs

public class Program
{
    public static IConfiguration Configuration  => new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
        .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCOre_ENVIRONMENT") ?? "Production"}.json")
        .AddEnvironmentVariables()
        .Build();
    public static int Main(string[] args)
    {
        Log.Logger = new LoggerConfiguration().ReadFrom.Configuration(Configuration)
            .MinimumLevel.Debug()//最小级别
            .Enrich.FromLogContext()//使用Serilog.Context.LogContext中的属性来丰富日志事件。
            .WriteTo.Console(new RenderedCompactJsonFormatter())//控制台使用Json格式输出
            .WriteTo.File(formatter: new CompactJsonFormatter(), "logs\\myapp.txt", rollingInterval: RollingInterval.Day)//天为单位以Json格式输出到指定的文件中去
            .CreateLogger();//创建日志
        try
        {
            Log.Information("Starting web host");
            CreateHostBuilder(args).Build().Run();
            return 0;
        }
        catch (Exception ex)
        {
            Log.Fatal(ex, "Host terminated unexpectedly");
            return 1;
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }
    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            })
            .UseSerilog(dispose:true);
}

WeatherForecastController.cs

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };
    private readonly ILogger<WeatherForecastController> _logger;
    public WeatherForecastController(ILogger<WeatherForecastController> logger)
    {
        _logger = logger;
    }
    [HttpGet]
    public IEnumerable<WeatherForecast> Get()
    {
        _logger.LogInformation("Create a log data");
        var rng = new Random();
        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
        {
            Date = DateTime.Now.AddDays(index),
            TemperatureC = rng.Next(-20, 55),
            Summary = Summaries[rng.Next(Summaries.Length)]
        })
        .ToArray();
    }
}

运行效果

这里我们在最后一行看得到Create a log data,但日志太多了很难看到我们想要的东西，所以我们可以对appsetting.json进行修改，将日志级别调高为Error

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "Serilog": {
    "MinimumLevel": {
      "Default": "Error",
      "Override": {
        "Microsoft": "Error",
        "System": "Information"
      }
    }
  },
  "AllowedHosts": "*"
}

第二次运行