Can't see logs in Azure Log Stream - azure

Question

In my Web Api App, I have the controller:
[Route("api/[controller]")]
public class ValuesController : Controller
{
// GET api/values
[HttpGet]
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
// GET api/values/5
[HttpGet("{id}")]
public string Get(int id)
{
System.Diagnostics.Trace.TraceInformation("in get...");
return "value";
}
}
I want to be able to see the log "in get..." on Azure when I publish it. On Azure, in the App Service Logs I turn on Application Logging (Filesystem) and set the level to Information. In the Log Stream, when I go to the url of the method, I see in the logs:
Connecting... 2020-02-09T06:07:38 Welcome, you are now connected to
log-streaming service. The default timeout is 2 hours. Change the
timeout with the App Setting SCM_LOGSTREAM_TIMEOUT (in seconds).
2020-02-09 06:08:07.158 +00:00 [Information]
Microsoft.AspNetCore.Hosting.Internal.WebHost: Request starting
HTTP/1.1 GET
http://testapi20200208104448.azurewebsites.net/api/values/5 2020-02-09
06:08:07.159 +00:00 [Information]
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker: Executing
action method TestApi.Controllers.ValuesController.Get (TestApi) with
arguments (5) - ModelState is Valid 2020-02-09 06:08:07.160 +00:00
[Information] Microsoft.AspNetCore.Mvc.Internal.ObjectResultExecutor:
Executing ObjectResult, writing value
Microsoft.AspNetCore.Mvc.ControllerContext.
But I don't see my log "in get..."

Answer 1

This is a known issue for .NET core (but for .NET framework, it can work well).
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 ValuesController:
public class ValuesController : Controller
{
private readonly ILogger _logger;
public ValuesController(ILoggerFactory loggerFactory)
{
_logger = loggerFactory.CreateLogger<ValuesController>();
}
// GET api/values
[HttpGet]
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
// GET api/values/5
[HttpGet("{id}")]
public string Get(int id)
{
//System.Diagnostics.Trace.TraceInformation("in get...");
//use ILogger here.
_logger.LogInformation("in get...");
return "value";
}
}

Answer 2

Ivan's answer did not fully work for me on aspnetcore 3.1, but it led me to this article, which gave me all information I needed:
https://learn.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-3.1