R – An event log source that’s always available for writing

asp.netcontingencyevent-logeventlog-sourcefallback

Is there an event log source that's always available for writing by an ASP.NET webapp?

Backstory, in case anyone has a seemingly unrelated solution:

Our ASP.NET webapp uses its own event log source, but it doesn't have the rights to create it. So, if the event log source doesn't exist when the webapp tries to write the entry (install instructions dictate that the admin register the event log source manually, but……) , our webapp doesn't put anything in the event log when it has problems.

I'm hoping there's another (app-agnostic) source I can use to notify the folks who watch the event log.

Best Answer

In this KB article it explains the issue http://support.microsoft.com/kb/329291

PRB: "Requested Registry Access Is Not Allowed" Error Message When ASP.NET Application Tries to Write New EventSource in the EventLog

Symptoms

When you use ASP.NET to create a new event source in the event log, you may receive the following error message:

System.Security.SecurityException: Requested registry access is not allowed.

Cause

By default, the user token of the ASP.NET worker process is ASPNET (or NetworkService for applications that run on Internet Information Services [IIS] 6.0). The problem in the "Symptoms" section occurs because your account does not have the correct user rights to create an event source.

Resolution

First approach:

Create an event source under the Application event log in Registry Editor (on the server, not your development PC). To do this, follow these steps:

  1. Access the server's Windows desktop. Click Start, and then click Run.
  2. In the Open text box, type regedit.
  3. Locate the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application
  4. Right-click the Application subkey, point to New, and then click Key.
  5. Type "TEST" for the key name.
  6. Close Registry Editor.

Second (alternative) approach:

The EventLogInstaller class in the System.Diagnostics namespace permits you to install and configure an event log that your application reads from or writes to while running. You can create an event source by using EventLogInstaller. To do this, follow these steps:

  1. Use Microsoft Visual Basic .NET or Microsoft Visual C# .NET to create a new Class Library named EventLogSourceInstaller. By default, the Class1.vb file or the Class1.cs file is created.
  2. In Solution Explorer, right-click EventLogSourceInstaller, and then click Add References.
  3. In the Add Reference dialog box, double-click System.Configuration.Install.dll, and then click OK.
  4. Rename the Class1.vb`Class1.cs` to MyEventLogInstaller.vb\MyEventLogInstaller.cs.
  5. Replace the existing code in MyEventLogInstaller.vb or MyEventLogInstaller.cs with the following sample code: Visual Basic .NET sample
Imports System.Diagnostics
Imports System.Configuration.Install
Imports System.ComponentModel

<RunInstaller(True)> _
Public Class MyEventLogInstaller
    Inherits Installer
    Private myEventLogInstaller As EventLogInstaller

    Public Sub New()
        ' Create an instance of 'EventLogInstaller'.
        myEventLogInstaller = New EventLogInstaller()
        ' Set the 'Source' of the event log, to be created.
        myEventLogInstaller.Source = "TEST"
        ' Set the 'Log' that the source is created in.
        myEventLogInstaller.Log = "Application"
        ' Add myEventLogInstaller to 'InstallerCollection'.
        Installers.Add(myEventLogInstaller)
    End Sub 
End Class

Visual C# .NET sample

using System;
using System.Diagnostics;
using System.ComponentModel;
using System.Configuration.Install;


namespace EventLogSourceInstaller 
{
  [RunInstaller(true)]
  public class MyEventLogInstaller : Installer
  {
      private EventLogInstaller myEventLogInstaller;

      public MyEventLogInstaller()
      {
          //Create Instance of EventLogInstaller
          myEventLogInstaller = new EventLogInstaller();

          // Set the Source of Event Log, to be created.
          myEventLogInstaller.Source = "TEST";

          // Set the Log that source is created in
          myEventLogInstaller.Log = "Application";
          
          // Add myEventLogInstaller to the Installers Collection.
          Installers.Add(myEventLogInstaller);
      }
  }
}
  1. On the Build menu, click Build Solution to create EventLogSourceInstaller.dll.
  2. Open the Visual Studio .NET Command Prompt.
  3. At the command prompt, change to the folder where EventLogSourceInstaller.dll is located.
  4. Run the following command to create the EventSource: InstallUtil EventLogSourceInstaller.dll

If you use the second approach under the resolution you should get it to work.

If you don't want to do that or you can't get it to work correctly another way would be to use the identity tag in your web.config and impersonate a user that does have rights to edit the registry. This is a security whole only for this application but if you implement some extra security measures you should be fine.

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