Wire and inject NLog into .NET Core console app

user_4298 0
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I created a consumer/job that I will have running as a process on Linux written in C#.

The process will:

  1. Read a message from RabbitMQ
  2. Make changes to the database
  3. Log any errors

All the documentation on NLog about .NET Core are on ASP.NET Core. When I try to get an ILogger implementation, it returns null.

Here is an except of wiring and usage:

static void ConfigureServices()
{
    string environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");

    var builder = new ConfigurationBuilder()
         .SetBasePath(Path.Combine(AppContext.BaseDirectory))
         .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
         .AddJsonFile($"appsettings.{environment}.json", optional: true);

    var services = new ServiceCollection();

    Configuration = builder.Build();

    [...]

    services.AddLogging();

    ServiceProvider = services.BuildServiceProvider();

    var loggerFactory = ServiceProvider.GetService<ILoggerFactory>();
    loggerFactory.AddNLog();
}

static void Main(string[] args)
{
    ConfigureServices();
    
    var logger = ServiceProvider.GetService<NLog.ILogger>();

    logger.Debug("Logging");

    [...]
}

Do not be confused with the environment variable ASPNETCORE_ENVIRONMENT; it is used solely to determine which appsettings.json to use.

I've based my code on this issue report.

Finally, these are the packages I currently have installed.

<ItemGroup>
  <PackageReference Include="Microsoft.EntityFrameworkCore" Version="1.1.2" />
  <PackageReference Include="Microsoft.Extensions.Configuration" Version="1.1.2" />
  <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" Version="1.1.2" />
  <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="1.1.2" />
  <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="1.1.2" />
  <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="1.1.2" />
  <PackageReference Include="NLog" Version="5.0.0-beta09" />
  <PackageReference Include="NLog.Extensions.Logging" Version="1.0.0-rtm-beta5" />
  <PackageReference Include="Npgsql" Version="3.2.4.1" />
  <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="1.1.0" />
</ItemGroup>
.net-core nlog c#
3 Answers

In DotNet Core 2 you can use the start up class now and clean up the code a bit to look more like the web one.

And as a bonus a way to start your app inside the DI container using ConsoleApp

Program.cs 

static void Main(string[] args)
{
    IServiceCollection services = new ServiceCollection();

    Startup startup = new Startup();
    startup.ConfigureServices(services);

    IServiceProvider serviceProvider = services.BuildServiceProvider();

    // entry to run app
    serviceProvider.GetService<ConsoleApp>().Run();
}

Startup.cs

public class Startup
{
    IConfigurationRoot Configuration { get; }

    public Startup()
    {
        var builder = new ConfigurationBuilder()
          .SetBasePath(Directory.GetCurrentDirectory())
          .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);

        Configuration = builder.Build();
    }


    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IConfigurationRoot>(Configuration);

        services.AddSingleton<IMyConfiguration, MyConfiguration>();

        services.AddLogging(loggingBuilder => {
           loggingBuilder.AddNLog("nlog.config");
        });

        services.AddTransient<ConsoleApp>();
    }
}

ConsoleApp.cs

public class ConsoleApp
{
    private readonly ILogger<ConsoleApp> _logger;
    private readonly IMyConfiguration _config;

    public ConsoleApp(IMyConfiguration configurationRoot, ILogger<ConsoleApp> logger)
    {
        _logger = logger;
        _config = configurationRoot;
    }


    public void Run()
    {
        var test = _config.YourItem;

        _logger.LogCritical(test);

        System.Console.ReadKey();
    }
}

Configuration.cs

public class MyConfiguration : IMyConfiguration
{

    IConfigurationRoot _configurationRoot;
    public MyConfiguration(IConfigurationRoot configurationRoot)
    {
        _configurationRoot = configurationRoot;
    }

    public string YourItem => _configurationRoot["YourItem"];
}


public interface IMyConfiguration
{
    string YourItem { get; }
}
user_7063630
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