Working with the system event log

The event log stores information about all events that occur in the system. It is useful to view logged information if unwanted behavior occurs in the system and you want to find out where the problem originates or get additional details.

Viewing the event log

To view the event log, open the Event log application.

If you click Display event () next to an event, the system displays a dialog with full details about the event.

Configuring the event log

You can configure the following event log settings:

• General event log settings
• Logging page not found exceptions
• Configuring permissions for the event log
• Logging system events to trace
• Logging system events in the Windows Event Viewer
• Setting up e-mail notifications for errors

General event log settings

You can configure the following settings for the event log in Settings -> System:

Logging page not found exceptions

You can enable logging of Page not found exceptions in the event log. To do so:

1. Open the Settings application.
2. Select the Content category.
3. In the Page not found group, enable Log page not found exception.
4. Save the changes.

Configuring permissions for the event log

To allow users to work with the event log, configure permissions for your website’s roles:

1. Open the Permissions application.

2. Select permissions for Modules and the Event log.

3. Assign the following permissions to roles:

   • Read - allows members of the roles to access the event log. Only users with the Global administrator privilege level can view events logged on a global application level.
   • Clear log - allows members of the roles to delete the records in the event log.

Logging system events to trace

You can set up Kentico to log application events in trace. You can then implement your own listener, such as the TextWriterTraceListener or use the out-of-the-box Kentico functionality to log events into the Windows Event Viewer.

To enable logging of system events to trace:

1. In Kentico, open the Settings application.
2. Select the System category.
3. In the Event log settings group, enable Log to trace.
4. Save the changes.

Kentico now logs system events to trace. You can now implement your own listener, such as the TextWriterTraceListener.

Logging system events in the Windows Event Viewer

You can set up Kentico to log application events in the Windows Event Viewer. Note that to do that, Kentico uses the EventLogTraceListener:

Registering Kentico in Windows Event Log

1. Run the Kentico installer.
2. Modify the installation that you want to register in Windows Event Log.
3. Select the Registration of Kentico in Windows Event Log check box.
4. Apply Changes.

The installer registers Kentico in the Windows Event Log.

Enabling logging of Kentico events into Windows Event Log

1. In Kentico, open the Settings application.
2. Select the System category.
3. In the Event log settings group, enable Log to trace and Use EventLog trace listener.
4. Save the changes.

Kentico now logs system events to both the Kentico event log and Windows Event Viewer.

Setting up e-mail notifications for errors

You can configure the system to automatically send e-mail notifications whenever errors occur in the application.

1. Open the Settings application.
2. Select the System category.
3. Enter the target e-mail addresses for the notifications into the Error notification e-mail address setting.
   • Use semicolons to separate multiple addresses.
4. Type a sender address into the No-reply e-mail address settings.
   • The notification e-mails use the sender address in their From field.
5. Save the settings.

Event log API

You can find an API example of logging events into the event log in Designing secure error messages. More examples are provided in the API examples application.

Disabling logging for specific types of events

If you wish to disable logging for events of a specific type, you can use custom code and the Kentico API.

The static EventLogProvider class (available in the CMS.EventLog library) provides the following properties:

• RegExExcludeLogSource
• RegExExcludeLogCode
• RegExExcludeLogDescription

The properties allow you to define regular expressions that exclude events whose value in the Source, Event code or Description field matches the specified expression (each field corresponds to one of the properties). Create and assign an instance of the System.Text.RegularExpression.Regex class as the value of the properties.

You need to set the properties at the beginning of the application’s life cycle. Choose one of the following options:

• During the initialization process of the application itself – use the CMSModuleLoader partial class in the App_Code folder.
• When initializing custom modules – override the OnInit method of the module class.

For example, you can add a new class to the App_Code folder of your web project (or CMSApp_AppCode -> Old_App_Code on web application installations) with the following code:

using System;
using System.Text.RegularExpressions;

using CMS.Base;
using CMS.EventLog;

[EventLogExcluder]
public partial class CMSModuleLoader
{
    /// <summary>
    /// Attribute class for running code during the application initialization.
    /// </summary>
    private class EventLogExcluderAttribute : CMSLoaderAttribute
    {
        /// <summary>
        /// Called automatically when the application starts.
        /// </summary>
        public override void Init()
        {
            // Excludes all events with the "CREATEOBJ" or "UPDATEOBJ" event codes.
            // Disables event log records notifying about the creation or update of objects in the system,
            // but still allows events related to object deletion.
            EventLogProvider.RegExExcludeLogCode = new Regex("^(CREATEOBJ|UPDATEOBJ)$");
        }
    }
}