How do I write logs from within Startup.cs?

Question

In order to debug a .NET Core app which is failing on startup, I would like to write logs from within the startup.cs file. I have logging setup within the file that can be u

Answer 1

Main code:

public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup()
            .Build();
}

CreateDefaultBuilder sets up a default console logger.

... configures the ILoggerFactory to log to the console and debug output

Startup code:

using Microsoft.Extensions.Logging;
...
public class Startup
{
    private readonly ILogger _logger;

    public Startup(IConfiguration configuration, ILoggerFactory logFactory)
    {
        _logger = logFactory.CreateLogger();
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        _logger.LogInformation("hello stackoverflow");
    }

I couldn't get the injection of an ILogger to work, but perhaps that's because it's not a controller. More info welcome!

Refs:

• https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-2.1&tabs=aspnetcore2x