Log Stream of App Service stopped working

Question

Log Stream of App Service stopped working

Alexander Großauer 101

I used the Log Stream feature quite often and it worked very well. But some time ago it stopped working at all.

I turn on "Application Logging (File System)" and set the Level to "Information" as always, but I don't see any of my log messages in the stream.

It is an ASP.net Core App.

No new logfile is created in D:\home\LogFiles\Application

It seems like the content of D:\home\LogFiles\SiteExtensions\DaaS\some-guid.txt is written to the log stream instead...??

SnehaAgrawal-MSFT 11,441 Reputation points Microsoft Employee

2019-12-17T08:11:22.92+00:00

Thanks for asking question! Could you Please take a look on your Azure App Service settings, WEBSITE_LOCAL_CACHE_OPTION. This might be a reason why Log Stream of App Service stopped working. You may also try to scale up to medium size worker and then again scale down to the small size worker. Let me know how it goes.
Alexander Großauer 101 Reputation points

2019-12-17T14:35:54.397+00:00

Thanks for your reply. Local cache is currently not activated, we plan to activate it in the future though. But as far as I know the local cache should just delay the log stream and not deactivate it, right?
I guess scaling up and down will trigger a restart of the app service. We want to avoid restarts during the week whenever possible. I will try it on the weekend and keep you posted.
Jeremy Brooks 572 Reputation points Microsoft Employee

2020-01-13T15:01:59.54+00:00

Try setting the log level to verbose to capture everything being outputted.
Alexander Großauer 101 Reputation points

2020-01-22T10:34:33.593+00:00

Thanks Jeremy, I tried that but unfortunately still no output.

SnehaAgrawal-MSFT 11,441 Reputation points Microsoft Employee

2019-12-17T08:11:22.92+00:00

Thanks for asking question! Could you Please take a look on your Azure App Service settings, WEBSITE_LOCAL_CACHE_OPTION. This might be a reason why Log Stream of App Service stopped working. You may also try to scale up to medium size worker and then again scale down to the small size worker. Let me know how it goes.
Alexander Großauer 101 Reputation points

2019-12-17T14:35:54.397+00:00

Thanks for your reply. Local cache is currently not activated, we plan to activate it in the future though. But as far as I know the local cache should just delay the log stream and not deactivate it, right?
I guess scaling up and down will trigger a restart of the app service. We want to avoid restarts during the week whenever possible. I will try it on the weekend and keep you posted.
Jeremy Brooks 572 Reputation points Microsoft Employee

2020-01-13T15:01:59.54+00:00

Try setting the log level to verbose to capture everything being outputted.
Alexander Großauer 101 Reputation points

2020-01-22T10:34:33.593+00:00

Thanks Jeremy, I tried that but unfortunately still no output.

Answer 1

I fixed the problem by adding the AzureWebAppDiagnostics Logging provider.
A few months ago this was not needed, so it seems the defaults have been changed at some time.

public static IHostBuilder CreateHostBuilder(string[] args) =>  
    Host.CreateDefaultBuilder(args)  
        .ConfigureLogging(logging =>  
        {  
            logging.AddAzureWebAppDiagnostics();     
        })  
        .ConfigureWebHostDefaults(webBuilder =>  
        {  
            webBuilder.UseStartup();  
        });

See https://learn.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-3.1

Answer 2

SnehaAgrawal-MSFT 11,441 Microsoft Employee

@Alexander Großauer Thanks for the reply! To add to this the Filesystem option is for temporary debugging purposes and turns itself off in 12 hours. So, could you try changing it to blob option which is for long-term logging and require blob storage container. Let me know how it goes.

Reference: https://learn.microsoft.com/en-us/azure/app-service/troubleshoot-diagnostic-logs#enable-application-logging-windows

Alexander Großauer 101 Reputation points

2020-01-22T10:12:11.127+00:00

Thank you, but a logging for temporary debugging purposes is exactly what I need. I don't want to store any logs long-term.

Log Stream of App Service stopped working

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