How do I need to log to see my logs in App Service logs

Question

I have enabled logging to Application logging to both FileSystem and Blob. I log messages using ILogger<T>.LogInformation() and Trace.WriteLine(). None of those are visible in blob. I also cannot find them on filesystem. I also can't see them when I enable log streaming.

Do I need to configure something in my ASP.NET Core application?

Answer 1

The [Microsoft.Extensions.Logging.AzureAppServices][1] provider package writes logs to text files in an Azure App Service app's file system and to blob storage in an Azure Storage account.

The provider package isn't included in the shared framework. To use the provider, add the provider package to the project.

To configure provider settings, use AzureFileLoggerOptions and AzureBlobLoggerOptions, as shown in the following example:

public static void Main(string[] args)
{
    var host = CreateHostBuilder(args).Build();

    var todoRepository = host.Services.GetRequiredService<ITodoRepository>();
    todoRepository.Add(new Core.Model.TodoItem() { Name = "Feed the dog" });
    todoRepository.Add(new Core.Model.TodoItem() { Name = "Walk the dog" });

    var logger = host.Services.GetRequiredService<ILogger<Program>>();
    logger.LogInformation("Seeded the database.");

    host.Run();
}

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureLogging(logging => logging.AddAzureWebAppDiagnostics())
            .ConfigureServices(serviceCollection => serviceCollection
                .Configure<AzureFileLoggerOptions>(options =>
                {
                    options.FileName = "azure-diagnostics-";
                    options.FileSizeLimit = 50 * 1024;
                    options.RetainedFileCountLimit = 5;
                }).Configure<AzureBlobLoggerOptions>(options =>
                {
                    options.BlobName = "log.txt";
                })
            )
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

You can refer below link for additional reference:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-3.1#azure-app-service-provider

Hope it helps.