How to fix obsolete ILoggerFactory methods?

Question

I upgraded my project to .NET Core 2.2.x and got an obsolete warning regarding the following code - both lines:

public void Configure(IApplicationBuilder app, 
                      IHostingEnvironment env, 
                      ILoggerFactory loggerFactory) 
  {
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));

The suggestion to fix is The recommended alternative is AddConsole(this ILoggingBuilder builder). I thought that is what I am using.

What am I missing here?

Answer 1

I had the same issue today.

Remove your logging configuration from Startup.cs and go to your Program.cs file and add something like:

var host = new WebHostBuilder()
    .UseKestrel()
    .UseContentRoot(Directory.GetCurrentDirectory())
    .UseIISIntegration()
    .UseStartup<Startup>()
    .ConfigureLogging((hostingContext, logging) =>
    {
        logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
        logging.AddConsole();
        logging.AddDebug();
    })
    .Build();

This used the 'builder' because the variable 'logging' is an IloggingBuilder (whereas your code is still using ILoggerFactory)

UPDATE: The other method I just tried is to stay inside Startup.cs but move the logging stuff from the 'Configure' method to 'ConfigureServices' like this:

public void ConfigureServices(IServiceCollection services)
{
    services.AddLogging(loggingBuilder =>
    {
        loggingBuilder.AddConfiguration(Configuration.GetSection("Logging"));
        loggingBuilder.AddConsole();
        loggingBuilder.AddDebug();
    });
}

Perhaps keeps the Program.cs less polluted...

Answer 2

The documentation's recommendation to use AddConsole(this ILoggingBuilder builder) is correct, but for that to work you need to add a reference to the NuGet package Microsoft.Extensions.Logging.Console.

Answer 3

I got the same warning when I was updating logging code from .Net Core 2.1 to 3.0. The recommended way to do the upgrade is documented on MSDN.

In my case, I was trying to get an instance of LoggerFactory for console which is pretty straightforward in .Net Core 3.0:

using (var loggerFactory = LoggerFactory.Create(builder => builder.AddConsole()))
{
    // use loggerFactory
}

Answer 4

Don't worry about it - this is the dumbest thing ever!

Note

The following code sample uses a ConsoleLoggerProvider constructor that has been obsoleted in version 2.2. Proper replacements for obsolete logging APIs will be available in version 3.0. In the meantime, it is safe to ignore and suppress the warnings.

In case you thought you forgot what Obsolete meant - you hadn't! Don't worry about it and just ignore it for now - or suppress the warning (sorry I don't have the code for that to hand).

(Wish they'd put a better explanation for why this was done - that's what I mean by dumb.)

Answer 5

According to the issue opened on GitHub for this, the replacement methods are already being called if you use CreateDefaultBuilder() method in your Program.cs.

https://github.com/aspnet/Docs/issues/9829

The only issue I have is that I only turned these on for non-Production environments.. and don't see a way to do so going forward.

Answer 6

If you don't have access to the LoggerFactory.Create(), use can still use the ILoggerFactory with the AddProvider() method giving it a ConsoleLoggerProvider() but it is a bit of a pain if you want to do something simple. The problem is, ConsoleLoggerProvider() requires a IOptionsMonitor<ConsoleLoggerOptions> as a parameter and the easiest thing to do if you

• you don't have access to the options mechanism in your code base (my problem), or
• the real options mechanisms in your existing code base don't match up with IOptionsMonitor<>, or
• you have other reasons not to use the ASP.Net options facilities

is to create a dummy class:

using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Console;
using Microsoft.Extensions.Options;
    
    class DummyConsoleLoggerOptionsMonitor : IOptionsMonitor<ConsoleLoggerOptions>
    {
        private readonly ConsoleLoggerOptions option = new ConsoleLoggerOptions();

        public DummyConsoleLoggerOptionsMonitor(LogLevel level)
        {
            option.LogToStandardErrorThreshold = level;
        }

        public ConsoleLoggerOptions Get(string name)
        {
            return this.option;
        }

        public IDisposable OnChange(Action<ConsoleLoggerOptions, string> listener)
        {
            return new DummyDisposable();
        }

        public ConsoleLoggerOptions CurrentValue => this.option;

        private sealed class DummyDisposable : IDisposable
        {
            public void Dispose()
            {
            }
        }
    }

You can then use your ILoggerFactory like:

factory.AddProvider(
    new ConsoleLoggerProvider(
        new DummyConsoleLoggerOptionsMonitor(LogLevel.Debug)));