Using Serilog in DXP

TL;DR Use Serilog.Sinks.Console for DXP apps — or skip Serilog entirely and rely on default logging.

It’s common during investigations that all the downloadable logs from the PaaS portal are empty.

In most cases, this happens because Serilog is used and configured to only write logs to files. While that works locally or in traditional hosting environments, it doesn’t play well with how Optimizely DXP handles logs.

What’s important to understand (maybe not clearly defined in documentation) is that the logs available in the PaaS Portal are App Service Console Logs and not file-based logs.

If your goal is to use Serilog for local development or debugging, you can simply follow the setup used in the Foundation project. That configuration works perfectly fine for DXP.

Implementing Serilog for Both Development and DXP

Below is an example of how the Program class can look. It uses a bootstrap logger during startup which ensures that logging is available even before the host is fully built, while still letting Serilog load its settings from configuration later on.

public class Program
{
    public static void Main(string[] args)
    {
        Log.Logger = new LoggerConfiguration()
            .MinimumLevel.Override("Microsoft", LogEventLevel.Information)
            .WriteTo.Console()
            .CreateBootstrapLogger();


        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureCmsDefaults()
            .UseSerilog((context, services, configuration) =>
            {
                configuration
                    .ReadFrom.Configuration(context.Configuration)
                    .ReadFrom.Services(services)
                    .Enrich.FromLogContext();
            })
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

This setup requires the NuGet packages Serilog, Serilog.AspNetCore and Serilog.Sinks.Console are installed.

Configuration for Development

In development, you might want to see logs both in the console and written to a local file for troubleshooting.

Your appsettings.Development.json could look like this:

{
  "Serilog": {
    "Using": ["Serilog.Sinks.Console", "Serilog.Sinks.File"],
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "EPiServer": "Information",
        "EPiServer.Commerce": "Warning",
        "Microsoft.Hosting.Lifetime": "Warning",
        "MySite.SomeNamespace": "Information"
      }
    },
    "WriteTo": [
      { "Name": "Console" },
      {
        "Name": "File",
        "Args": {
          "path": "app_data/log.txt",
          "rollingInterval": "Day",
          "retainedFileCountLimit": 10
        }
      }
    ]
  }
}

This configuration assumes the package Serilog.Sinks.File is installed.

Configuration for DXP

Logs written to the console are captured as App Service Console Logs. These are the logs visible in the DXP portal.

For DXP, you can simplify and optimize Serilog by only using the console sink, optionally wrapped in an async sink which may or may not improve performance. This is how appsettings.<ENV>.json could look like:

{
  "Serilog": {
    "Using": ["Serilog.Sinks.Async", "Serilog.Sinks.Console"],
    "MinimumLevel": {
      "Default": "Warning",
      "Override": {
        "Microsoft": "Warning",
        "EPiServer": "Warning",
        "EPiServer.Commerce": "Warning",
        "Microsoft.Hosting.Lifetime": "Information",
        "MySite.SomeNamespace": "Information"
      }
    },
    "WriteTo": [
      {
        "Name": "Async",
        "Args": {
          "configure": [
            { "Name": "Console" }
          ]
        }
      }
    ]
  }
}

The configuration assumes that Serilog.Sinks.Async and Serilog.Sinks.Console are installed.

With this setup, you can enjoy all the benefits of Serilog’s structured logging while ensuring that logs are still captured correctly in Optimizely DXP.