ASP.NET Core - Logging

Enriched Logging with Serilog

To enable Serilog logging, update the default program.cs from,

public class Program
{
    public static IHostBuilder CreateHostBuilder(string[] args) =>
                Host.CreateDefaultBuilder(args)
                    .ConfigureWebHostDefaults(webBuilder =>
                    {
                        webBuilder.UseStartup<Startup>();
                    });

    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }
}

To

using Serilog;
using Code.Library.AspNetCore.Helpers;
public class Program
{
    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            })
        .UseSerilog((hostingContext, loggerConfiguration) => loggerConfiguration.WithSimpleConfiguration(hostingContext.Configuration));

    public static int Main(string[] args)
    {
        try
        {
            CreateHostBuilder(args).Build().Run();
            return 0;
        }
        catch (Exception ex)
        {
            Log.Fatal(ex, "Host terminated unexpectedly");
            return 1;
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }

}

You don't need to install Serilog via NuGet since it's a dependency for Code.Library.AspNetCore and will get installed automatically when you add Code.Library.AspNetCore via NuGet.

By doing so, it will generate logs under "logs" folder in the root directory. And a sample log looks like,

{
  "@t": "2020-04-25T13:55:20.3908717Z",
  "@m": "HTTP \"GET\" \"/liveness\" responded 200 in 5.5626 ms",
  "@i": "62d0885c",
  "Host": "localhost:5015",
  "Protocol": "HTTP/1.1",
  "Scheme": "http",
  "ContentType": "text/plain",
  "UserAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.113 Safari/537.36",
  "ClientIP": "::1",
  "UserName": "(anonymous)",
  "RequestMethod": "GET",
  "RequestPath": "/liveness",
  "StatusCode": 200,
  "Elapsed": 5.5626,
  "SourceContext": "Serilog.AspNetCore.RequestLoggingMiddleware",
  "RequestId": "0HLV93VUMSS33:00000002",
  "SpanId": "7b3e3dd92277ae4c",
  "TraceId": "81595b40301ed846b6e9a9b3fbac85d5",
  "ParentId": "0000000000000000",
  "ConnectionId": "0HLV93VUMSS33",
  "MachineName": "WORKSTN1",
  "Assembly": "Projet.Name.API",
  "Version": "1.0.0.0"
}

Logging Settings

Refine the logs by adding the below to the appsettings.json,

"Serilog": {
    "MinimumLevel": {
      "Default": "Debug",
      "Override": {
        "Microsoft": "Warning",
        "System": "Warning",
        "IdentityServer4": "Information",
        "Orleans": "Warning"
      }
    },
    "SeqServerUrl": null,
    "WriteToFile" : false,
    "UseElasticsearchFormatter": false,
}

SeqServerUrl

If SeqServerUrl is provided (ex. "http://localhost:5341/"), then seq sink gets attached to the Serilog. It's very useful in case of local development.

WriteToFile

To enable logging to file, set it to true. Default value is false.

UseElasticsearchFormatter

Set this to true if you want your console logs to written in elasticsearch format, useful in case of hosting in k8s where EFK configured to collect logs. Default value is false.

We don't need the default Logging configuration in the appsettings.json anymore, remove it.

"Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },

Also, remember to exclude the logs directory from version control.

HTTP Request Response Logging

Under Startup.cs Configure method,

app.UseRequestResponseLogging();

This will produce log in the following format for each request.

----- Handled HTTP Request "http://orderin...00:00.0000885\",\"status\":\"Healthy\"}}}")
HTTP "GET" "/hc" responded 200 in 1.3573 ms
----- Handling HTTP Request "http://ordering.api.test.empay.ae/hc" ("")

Request Response Logging Options

Include

RequestHeaders

Set this to true to enable request headers logging. This is disabled by default.

Exclude

HealthChecks

This will exclude logging for all endpoints with endpoint name "Health checks". This is enabled by default.

Paths

No logs for matching paths. Default values are ["/hc", "/liveness"]

RequestBody

Request body will not be logged for matching paths

ResponseBody

Response body will not be logged for matching paths

Request logging

Under Startup.cs Configure method,

app.UseRequestLogging();

Which internally uses Serilog's default request logging along with the enrichers.

Flurl request logging

To enable logging requests made by Flurl, add following under ConfigureServices

 services.AddFlurlTelemetry();