Writes log message to the Event Log.

Supported in .NET and Mono ##Configuration Syntax

<targets>
  <target xsi:type="EventLog"
          name="String"
          layout="Layout"
          machineName="String"
          source="Layout" 
          category="Layout"
          eventId="Layout"
          log="String"
          maxMessageLength="Integer" />
<!-- note: source is a string in NLog before 4.0 -->

</targets>

Read more about using the [Configuration File](Configuration file).

##Parameters ###General Options

• name - Name of the target.

###Layout Options

• layout - Layout used to format log messages. Layout Required. Default: ${longdate}|${level:uppercase=true}|${logger}|${message}. Note: max size of 16384 characters (limitation of the EventLog API)

###Event Log Options

• machineName - Name of the machine on which Event Log service is running. Default: .
• source - Value to be used as the event Source. By default this is the friendly name of the current AppDomain. From NLog 4.0 this is layoutable(Layouts).
• category - Layout that renders event Category. The categories must be predefined for the specified source and needs to be numeric.
• eventId - Layout that renders event ID.
• log - Name of the Event Log to write to. This can be System, Application or any user-defined name. Default: Application
• MaxMessageLength - The message length limit to write to the Event Log. There are various message length limit that depends on the OS. Therefore, be careful for the value. Default: 16,384. If given value is zero or negative, then Exception will throw. Introduced in NLog 4.3.
• onOverflow - Action to take when a log message is larger than the MaxMessageLength option. Available actions are:
  • Truncate. Truncates the message before writing to the Event Log. This is the default.
  • Split. Splits the message and writes multiple entries to the Event Log. Warning: the message layout will be spread across multiple Event Log entries; if there is an application reading and parsing the Event Log, split messages will not have the expected layout of a log entry.
  • Discard. Discards of the message. It will not be written to the Event Log.

##Notes To log to the event log, an event source is required to exist. This involves creating the event source.

When install/uninstalling, the event source is only created / removed when the source doesn't contain layout renderers.

When installing, the event source can only be created when run as an Administrator. Alternatively a simple PowerShell command to create this source is shown below (run PowerShell as Administrator).

New-EventLog -LogName Application -Source "MySourceName"

The Event Log has a limit in the number of bytes in a message. From MSDN:

The message string is longer than 31,839 bytes (32,766 bytes on Windows operating systems before Windows Vista).

##Example

<target xsi:type="EventLog"
            name="eventlog"
            source="test"
            layout="${message}${newline}${exception:format=ToString}"/>