logging

Serilog Structured Logging

Reference material for adding and using Serilog in ASP.NET Core. Used by dnp-architect and dnp-tdd-developer-hard.

NuGet Packages

<PackageReference Include="Serilog.AspNetCore" Version="8.*" />
<PackageReference Include="Serilog.Enrichers.Environment" Version="3.*" />
<PackageReference Include="Serilog.Enrichers.Thread" Version="4.*" />
<PackageReference Include="Serilog.Formatting.Compact" Version="3.*" />
<!-- Add sinks as needed: -->
<PackageReference Include="Serilog.Sinks.OpenTelemetry" Version="4.*" />

Setup — Program.cs

Replace the default ASP.NET Core logging before builder.Build():

builder.Host.UseSerilog((context, config) =>
    config
        .ReadFrom.Configuration(context.Configuration)
        .Enrich.FromLogContext()
        .Enrich.WithMachineName()
        .Enrich.WithThreadId()
        .WriteTo.Console(new CompactJsonFormatter())
        .WriteTo.OpenTelemetry()); // swap/add sinks as needed

For early startup errors, bootstrap a minimal logger before the host is built:

Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .CreateBootstrapLogger();
try
{
    var builder = WebApplication.CreateBuilder(args);
    builder.Host.UseSerilog((ctx, cfg) => cfg.ReadFrom.Configuration(ctx.Configuration)...);
    // ...
}
catch (Exception ex)
{
    Log.Fatal(ex, "Application startup failed.");
}
finally
{
    Log.CloseAndFlush();
}

appsettings.json Configuration

{
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "Microsoft.EntityFrameworkCore": "Warning",
        "Microsoft.EntityFrameworkCore.Database.Command": "Information",
        "System": "Warning"
      }
    }
  }
}

Flip EF Core's Database.Command override to Information temporarily when debugging query issues; revert before shipping.

Structured Logging — Message Templates

Always use message templates, never string interpolation. Interpolation loses the structured property; templates capture it.