How to enable Application Logs in Azure for Net Core 2 App?

Question

I am trying to enable application logs in azure. I have a dummy Net Core 2 App running in an appService in azure.

and basically my goal is to see the trace messages in the log stream and in the application log files but I have not found the right way to do this.

One of the challenge I have found reading other posts is that they assume a web config in place.

Answer 1

The documentation for ASP.NET Core 2.2 is here.

Firstly, enable Application Logging and choose the appropriate level:

This may be all you need to do to diagnose any problems. But if you want log messages and see them, install the Microsoft.Extensions.Logging.AzureAppServices NuGet package.

Then, configure logging:

using Microsoft.Extensions.Logging;

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
    .ConfigureLogging(logging =>
    {
        logging.AddAzureWebAppDiagnostics();
    })
    .UseStartup<Startup>();

Now you can inject and use ILogger:

public Startup(IConfiguration configuration, ILogger<Startup> logger)
{
    Configuration = configuration;
    this.logger = logger;
}

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.LogWarning("Starting up");

Then in the Azure App Service, click on Log stream:

Answer 2

Run dotnet add package EntityFramework Microsoft.Extensions.Logging.AzureAppServices to install logging extension to your project.

Program.cs file for reference:

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

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
             .ConfigureLogging((hostingContext, logging) =>
             {
                 logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                 logging.AddConsole();
                 logging.AddDebug();
                 logging.AddAzureWebAppDiagnostics();
             })
            .UseApplicationInsights()
            .UseStartup<Startup>()
            .Build();
}