Serilog and .NET Core 2.1 HostBuilder Configuration

Question

I'm using the .NET Core 2.1 HostBuilder class to set up and run a GRPC server and am having trouble getting SeriLog properly configured so that it is used by the .NET Core logging pipeline as well as available (via dependency injection) elsewhere in my app.

class Program
{
    private static async Task Main(string[] args)
    {
        var hostBuilder = new HostBuilder()
            .ConfigureServices((hostContext, services) =>
            {
                services.AddSingleton<ILogger>(BuildLogger);

                // other services here 
            })
            .ConfigureLogging((hostContext, loggingBuilder) =>
                loggingBuilder.AddSerilog(dispose: true));

        await hostBuilder.RunConsoleAsync();
    }

    private static ILogger BuildLogger(IServiceProvider provider)
    {

        // create a (global) logger
        Log.Logger = new LoggerConfiguration() 
            ...
            .CreateLogger();

        return Log.Logger;
    }
}

The problem is that I need the call to loggingBuilder.AddSerilog() to use the singleton ILogger that was registered with the DI services configuration a few lines above.

I realize I could directly call BuildLogger() to get the ILogger instance and register that instance with the DI service configuration, but it seems like I shouldn't have to. What I'm looking for is a way, from within the .ConfigureLogging() method to access a ServiceProvider instance so I can get the registered ILogger maybe like

serviceProvider.GetRequiredService<ILogger>();

and pass that to the AddSerilog() call. Any ideas?

Answer 1

Try the new package now available in Serilog - https://github.com/serilog/serilog-extensions-hosting.

  public static IHost BuildHost(string[] args) =>
    new HostBuilder()
        .ConfigureServices(services => services.AddSingleton<IHostedService, PrintTimeService>())
        .UseSerilog() // <- Add this line
        .Build();

Answer 2

What I'm looking for is a way, from within the .ConfigureLogging() method to access a ServiceProvider instance so I can get the registered ILogger

You can access the ServiceProvider from within the ConfigureLogging() method via ILoggingBuilder.Services.BuildServiceProvider(). Like so:

//...

private static async Task Main(string[] args)
{
    var hostBuilder = new HostBuilder()
        .ConfigureServices((hostContext, services) =>
        {
            services.AddSingleton<ILogger>(BuildLogger);

            // other services here 
        })
        .ConfigureLogging((hostContext, loggingBuilder) =>
            loggingBuilder.AddSerilog(
                loggingBuilder
                    .Services.BuildServiceProvider().GetRequiredService<ILogger>(),
                dispose: true));

    await hostBuilder.RunConsoleAsync();
}

...//

Answer 3

Here is a sample that shows how to do this including using appsettings.json for configuring serilog and how to get the logging using ILogger without having to manually inject it as the marked answer shows and how you can also you IOptions:

    public class Settings
{
    public string Sample { get; set; }
}

public class Service : IHostedService
{
    private readonly ILogger<Service> _logger;
    private Settings _settings;
    public Service(ILogger<Service> logger,
        Settings settings)
    {
        _logger = logger;
        _settings = settings;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }
}

class Program
{
    static async Task Main(string[] args)
    {
        var host = new HostBuilder()
                   .ConfigureHostConfiguration(builder =>
                   {
                       builder.AddJsonFile("hostsettings.json", optional: true);
                   })
                   .ConfigureAppConfiguration((hostContext, builder) =>
                   {
                       builder.AddJsonFile("appsettings.json");
                       builder.AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", optional: true);
                   })
                   .ConfigureLogging((hostContext, builder) =>
                   {
                       Log.Logger = new LoggerConfiguration()
                                    .ReadFrom.Configuration(hostContext.Configuration).CreateLogger();
                       builder.AddConfiguration(hostContext.Configuration.GetSection("Logging"));
                       builder.AddSerilog(dispose: true);
                   })
                   .ConfigureServices((hostContext, services) =>
                   {
                       var settings = hostContext.Configuration.GetSection("Configuration").Get<Settings>();
                       services.AddSingleton(settings);

                       services.AddHostedService<Service>();
                       services.AddLogging();
                       services.AddOptions();
                   })
                   .Build();

        using (host)
        {
            await host.StartAsync();
            await host.WaitForShutdownAsync();
        }
    }
}

Answer 4

According to documentation on the repo for .NET Core 2.0+, call AddSerilog() on the provided loggingBuilder and make sure to configure Serilog first:

//...

private static async Task Main(string[] args) {

    Log.Logger = new LoggerConfiguration()
        //...
        .CreateLogger();

    var hostBuilder = new HostBuilder()
        .ConfigureServices((hostContext, services) => {        
            services.AddLogging(loggingBuilder =>
                loggingBuilder.AddSerilog(dispose: true));

            // other services here 
        });

    await hostBuilder.RunConsoleAsync();
}

//...

Answer 5

some changes in .Net6

here is my program.cs

var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddSingleton<WeatherForecastService>();
Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Information()
    .MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
    .Enrich.FromLogContext()
    .WriteTo.Console()
    .CreateLogger(); 
builder.Host.UseSerilog( Log.Logger);
var app = builder.Build();