What to See Trace Logs for Azure App Service? - azure

Question

Using .NET Core 2 in Azure App Service. Don't see my logs. In the actual application, the logging code looks like this:
using System.Diagnostics;
...
Trace.WriteLine("Logging works");
I expected to see the Trace logs in the Log Stream, but I don't. I do see general API logs. What am I doing wrong? My config below:

Answer 1

I had the same issue for .NET core azure web app: Trace.WriteLine method does not work(not write message to Application logs) for .NET core, but work for .NET framework , and I find the issue about that.
As a workaround for .NET core web application, I suggest you can use ILogger, which can write message to Application Logs.
In Startup.cs -> Configure method, re-write Configure method like below:
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
//your other code
//add the following 2 lines of code.
loggerFactory.AddConsole();
loggerFactory.AddDebug();
app.UseStaticFiles();
//your other code
}
Then in HomeController.cs, add the following code:
public class HomeController : Controller
{
private readonly ILogger _logger;
public HomeController(ILoggerFactory loggerFactory)
{
_logger = loggerFactory.CreateLogger<HomeController>();
}
public IActionResult Index()
{
_logger.LogInformation("this is a information from ILogger...");
return View();
}
//other code
}
After publish to azure, and configure the Application Logging -> run the azure web app -> you can see the message is displayed in Application Logs: