how do i customize output for serilog?

There are three JSON formatters provided by the Serilog project:

  • Serilog.Formatting.Json.JsonFormatter – This is the historical default shipped in the Serilog package. It produces a complete rendering of the log event and supports a few configuration options.
  • Serilog.Formatting.Compact.CompactJsonFormatter – A newer, more space-efficient JSON formatter shipped in Serilog.Formatting.Compact.
  • Serilog.Formatting.Compact.RenderedCompactJsonFormatter – Also shipped in Serilog.Formatting.Compact, this formatter pre-renders message templates into text.

You could refer the following steps and use Serilog.Formatting.Compact to customize Serilog output:

  1. Install Serilog.AspNetCore via Nuget.

  2. Configure to use Serilog:

     public class Program
         public static int Main(string[] args)
             // CreateHostBuilder(args).Build().Run();
             Log.Logger = new LoggerConfiguration()
            .MinimumLevel.Override("Microsoft", LogEventLevel.Information)
            .WriteTo.File(new CompactJsonFormatter(), "log20201104.json")
                 Log.Information("Starting web host");
                 return 0;
             catch (Exception ex)
                 Log.Fatal(ex, "Host terminated unexpectedly");
                 return 1;
         public static IHostBuilder CreateHostBuilder(string[] args) =>
                 .ConfigureWebHostDefaults(webBuilder =>

    Remember to add the following reference:

     using Serilog;
     using Serilog.Events;
     using Serilog.Formatting.Compact;
  3. According to your code, it seems that you want to log the request and response information, if that is the case, you could also create a SerilogRequestLogger Middleware. Like this:

     public class SerilogRequestLogger
         readonly RequestDelegate _next;
         public SerilogRequestLogger(RequestDelegate next)
             if (next == null) throw new ArgumentNullException(nameof(next));
             _next = next;
         public async Task Invoke(HttpContext httpContext)
             if (httpContext == null) throw new ArgumentNullException(nameof(httpContext));
             // Push the user name into the log context so that it is included in all log entries
             LogContext.PushProperty("UserName", httpContext.User.Identity.Name);
             // Getting the request body is a little tricky because it's a stream
             // So, we need to read the stream and then rewind it back to the beginning
             string requestBody = "";
             Stream body = httpContext.Request.Body;
             byte[] buffer = new byte[Convert.ToInt32(httpContext.Request.ContentLength)];
             await httpContext.Request.Body.ReadAsync(buffer, 0, buffer.Length);
             requestBody = Encoding.UTF8.GetString(buffer);
             body.Seek(0, SeekOrigin.Begin);
             httpContext.Request.Body = body;
             Log.ForContext("RequestHeaders", httpContext.Request.Headers.ToDictionary(h => h.Key, h => h.Value.ToString()), destructureObjects: true)
                .ForContext("RequestBody", requestBody)
                .Debug("Request information {RequestMethod} {RequestPath} information", httpContext.Request.Method, httpContext.Request.Path);
             Log.Information(string.Format("Request Body: {0} ", requestBody));
             var exampleUser = new WebApplication2User { Id = "1001", UserName = "Adam", SecurityStamp = DateTime.Now.ToString() };
             Log.Information("Created {@User} on {Created}", exampleUser, DateTime.Now);
             // The reponse body is also a stream so we need to:
             // - hold a reference to the original response body stream
             // - re-point the response body to a new memory stream
             // - read the response body after the request is handled into our memory stream
             // - copy the response in the memory stream out to the original response stream
             using (var responseBodyMemoryStream = new MemoryStream())
                 var originalResponseBodyReference = httpContext.Response.Body;
                 httpContext.Response.Body = responseBodyMemoryStream;
                 await _next(httpContext);
                 httpContext.Response.Body.Seek(0, SeekOrigin.Begin);
                 var responseBody = await new StreamReader(httpContext.Response.Body).ReadToEndAsync();
                 httpContext.Response.Body.Seek(0, SeekOrigin.Begin);
                 Log.ForContext("RequestBody", requestBody)
                    .ForContext("ResponseBody", responseBody)
                    .Debug("Response information {RequestMethod} {RequestPath} {statusCode}", httpContext.Request.Method, httpContext.Request.Path, httpContext.Response.StatusCode);
                 await responseBodyMemoryStream.CopyToAsync(originalResponseBodyReference);
  4. Configure the SerilogRequestLogger Middleware in the Configure method:


Then, you could use the following code to log information:

            var exampleUser = new WebApplication2User { Id = "1001", UserName = "Adam", SecurityStamp = DateTime.Now.ToString() };
            Log.Information("Created {@User} on {Created}", exampleUser, DateTime.Now);

the result like this:

{“@t”:”2020-11-04T14:19:23.2065796Z”,”@mt”:”Created {@User} on {Created}”,”User”:{“Id”:”1001″,”Age”:0,”UserName”:”Adam”,”NormalizedUserName”:null,”Email”:null,”NormalizedEmail”:null,”EmailConfirmed”:false,”PasswordHash”:null,”SecurityStamp”:”11/4/2020 10:19:23 PM”,”ConcurrencyStamp”:”ca564733-9524-446f-8103-dd211cf8b44c”,”PhoneNumber”:null,”PhoneNumberConfirmed”:false,”TwoFactorEnabled”:false,”LockoutEnd”:null,”LockoutEnabled”:false,”AccessFailedCount”:0,”$type”:”WebApplication2User”},”Created”:”2020-11-04T22:19:23.2060830+08:00″,”UserName”:null,”RequestId”:”80000080-0005-fd00-b63f-84710c7967bb”,”RequestPath”:”/Home/Privacy”,”SpanId”:”|e29bfdb0-4bd9f6a34acb24d8.”,”TraceId”:”e29bfdb0-4bd9f6a34acb24d8″,”ParentId”:””}


Formatting JSON


How to add ‘request body’ in serilog’s output .net core?

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