Ability to use global property to point to log4net configuration file

• Key: LOG4NET-33
• Type: Improvement
• Status: Resolved
• Resolution: Fixed
• Priority: Minor
• Assignee: Nicko Cadell
• Reporter: patrick conant
• Component/s: Core
• Affects Version/s: 1.2.9
• Fix Version/s: 1.2.10

Description

The log4j tool has the ability to specify a system property to point to the logging configuration file. For instance, when starting a java program (such as tomcat), one can pass "-Dlog4j.configuration=http://mydomain/log4j.xml" as a command line parameter. Log4j checks to see whether this property is available and, if it is, uses the return value from the URL to configure categories and appenders.

A similar mechanism in log4net would allow a few improvements in logging configuring:
* No need to use the XmlConfiguratorAttribute in any assemblies
* No need to know at design time where the log4net config file will be located
* Ability to configure logging for all components in an app domain by setting a property in the app domain's config file
* Ability to configure logging for all components on a machine by setting a property in the machine.config file
* Ability to updating config file contents without updating app or machine config contents.

I'd propose doing a direct mirror of the log4j capabilities into log4net as follows:
* Update the LogManager class with a static constructor that mirrors the static block in the LogManager class in log4j
* Use System.Configuration.ConfigurationSettings.AppSettings.Get(...) instead of java's System.getProperty(...)
* Don't support the configuratorClass attribute (yet) because the XmlConfigurator seems to be the only logical choice
* Don't implement the DEFAULT_XML_CONFIGURATION_FILE or DEFAULT_CONFIGURATION_FILE property checks (yet).

Comments

[patrick conant]

This is a patch submittal including two files:

* LogManager.cd.diff.txt is a unified diff file for the LogManager.cs file. The patch contains a new static constructor that attempts to retrieve log4net configuration file location from the application setting "log4net.configuration".
* configuration.xml.diff.txt is a unified diff file for the configuration.xml XDoc source containing information on the new default initialization procedure. The contents of this added section are taken largely from http://logging.apache.org/log4j/docs/manual.html

[patrick conant]

Resubmitted with license granted. Sorry about that.

[patrick conant]

Here's another stab at enabling an appSettings property to confingure log4net. The new approach uses the DefaultRepositorySelector to configure only the default repository. This still has the XmlConfigurator hard-coded.

[Nicko Cadell]

Added code to the DefaultRepositorySelector to look for the AppSetting 'log4net.Config' when configuring the default repository. If this AppSetting is specified then the value is loaded as a URI relative to the application base directory and used to try to configure the repository.