ASP.NET 6 Core API does not write to Windows EventLog

Question

ASP.NET 6 Core API does not write to Windows EventLog

AG 456

Hi,

I have started a new ASP.NET 6 Core Web API with latest NuGet packages updated.
Repo is here LogTest

Add the necessary code according to this doc logging

At appsettings.json

  "EventLog": {  
    "LogLevel": {  
      "Default": "Information",  
      "Microsoft.Hosting.Lifetime": "Information"  
    }  
  }

At Program.cs

var builder = WebApplication.CreateBuilder(args);  
builder.Logging.ClearProviders();  
builder.Logging.AddConsole();  
  
builder.Logging.AddEventLog(eventLogSettings =>  
{  
    eventLogSettings.LogName = "LogTest";  
    eventLogSettings.SourceName = "Test1";  
});

At WeatherForecastController.cs I have added _logger.LogInformation("aaa"); at public IEnumerable<WeatherForecast> Get()

Register LogTest with PowerShell

New-EventLog -LogName LogTest -Source Test1

Ruining the app but nothing is written to Windows EventLog at LogTest.

Any help please?

Regards,
AG

Zhi Lv - MSFT 24,391 Reputation points Microsoft Vendor

2022-10-31T02:56:34.053+00:00
Hi @AG ,

You can try the following steps to narrow down the problem.

Try to remove the LogName and SourceName, then it will use the default name Application, you can check it in the Event Viewer, whether you can find these event log?
builder.Logging.AddEventLog(eventLogSettings => { // eventLogSettings.LogName = "LogTest"; // eventLogSettings.SourceName = "Test1"; });

If you still can't find the event log, the issue might relate event log setting, try to change the appsettings,json file as below: {
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft.AspNetCore": "Warning"
},
"EventLog": {
"LogLevel": {
"Default": "Information",
"Microsoft.Hosting.Lifetime": "Information"
}
}
},
"AllowedHosts": "*"
}

If you can find the event via the default name (Application), then, you can set the LogName and SourceName, after that use Event Viewer to view the log, in this scenario, if you still can't find the event log via the custom name, the issue might relate Powershell cmdlet (New-EventLog), please check the new log is create success, refer to this article.

Best regards,
Dillion

Zhi Lv - MSFT 24,391 Reputation points Microsoft Vendor

2022-10-31T02:56:34.053+00:00

Hi @AG ,

You can try the following steps to narrow down the problem.

Try to remove the LogName and SourceName, then it will use the default name Application, you can check it in the Event Viewer, whether you can find these event log?
builder.Logging.AddEventLog(eventLogSettings => { // eventLogSettings.LogName = "LogTest"; // eventLogSettings.SourceName = "Test1"; });

If you still can't find the event log, the issue might relate event log setting, try to change the appsettings,json file as below: {
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft.AspNetCore": "Warning"
},
"EventLog": {
"LogLevel": {
"Default": "Information",
"Microsoft.Hosting.Lifetime": "Information"
}
}
},
"AllowedHosts": "*"
}

If you can find the event via the default name (Application), then, you can set the LogName and SourceName, after that use Event Viewer to view the log, in this scenario, if you still can't find the event log via the custom name, the issue might relate Powershell cmdlet (New-EventLog), please check the new log is create success, refer to this article.

Best regards,
Dillion

Answer 1

Hi @Zhi Lv - MSFT

Thanks, it is working now but I have anther problem.
For every call to the API for example public IEnumerable<WeatherForecast> Get() a lot is written to the EventLog not just _logger.LogInformation("aaa"); so I have tried to implement a filter like this eventLogSettings.Filter = (x, y) => y >= LogLevel.Error; so only the logs I am writing and also Error's from the API will be written to the EventLog but I have no luck of doing so as when applying this filter nothing is written to the EventLog.

Thanks,
AG

Answer 2

AG 456

Hi @Zhi Lv - MSFT

Sorry but it does not work.
I am using IIS Express for Debug and also tried to change to Host and Debug but still many events are written to EventLog when app is starting.

var builder = WebApplication.CreateBuilder(args);  
  
builder.Logging.AddFilter((provider, category, logLevel) =>  
{  
    if (provider.Contains("ConsoleLoggerProvider")  
        && category.Contains("Host")  
        && logLevel >= LogLevel.Debug)  
    {  
        return true;  
    }  
    else  
    {  
        return false;  
    }  
});  
  
builder.Logging.ClearProviders();  
builder.Logging.AddConsole();  
  
builder.Logging.AddEventLog(eventLogSettings =>  
{  
    eventLogSettings.LogName = "LogTest";  
    eventLogSettings.SourceName = "Test1";  
});

Regards,
AG

Zhi Lv - MSFT 24,391 Reputation points Microsoft Vendor

2022-11-03T05:46:04.427+00:00
Hi @AG ,

It is my mistake, to filter the event log, we need to use the eventLogSettings.Filter like your previous reply, instead of using the builder.Logging.AddFilter.

Your previous code is correct, we need to use the following code:

builder.Logging.AddEventLog(eventLogSettings => { eventLogSettings.Filter = (x, y) => y >= LogLevel.Error eventLogSettings.LogName = "LogTest"; eventLogSettings.SourceName = "Test1"; });

About there is no information logged in the event log, it is because of you are using the _logger.LogInformation() to add information log, instead of the error log. But from the above code, we can see you are setting the log level as Error. So, the information log is not written to the event log. To write log to the event log, you can try to use _logger.LogError() method.

Best regards,
Dillion

Answer 3

Hi @Zhi Lv - MSFT

_logger.LogError() is working but I would like to be to write _logger.LogInformation() to EventLog so if I will put the filter on LogLevel.Information again I am receiving a lot of events when the app is starting and when calling public IEnumerable<WeatherForecast> Get()

Regards,
AG

Answer 4

AG 456

Apparently, only thing needs to do is set "Microsoft": "Warning" at appsettings.json so it will looks like this

"EventLog": {  
  "LogLevel": {  
    "Default": "Information",  
    "Microsoft": "Warning"  
    //"Microsoft.Hosting.Lifetime": "Information"  
  }  
}

Regards,
AG

ASP.NET 6 Core API does not write to Windows EventLog

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