Log4jruby

Log4jruby provides an interface mostly compatible with the standard ruby Logger but backed by Log4j. This makes the granular log output configuration, stacktrace output, and other facilities of log4j available to Java and Ruby code alike. For projects that extend/integrate Java already dependent on log4j, it allows log configuration for Java and Ruby code in one spot.

Note* Currently log4j 1.2 only

• Automatic stacktrace output (including nested causes) for logged exceptions
• Configure Java and Ruby logging together (e.g a single log4j.properties file) and gain log4j features such as runtime output targets for Ruby code.
• Supports inclusion of filename, line number, and method name in log messages via MDC. Note: tracing must be enabled.
• High level support for class based logging via the enable_logger macro.
• Compatible with the Rails logging.

Usage and examples

Enable class level logging via enable_logger

 require 'log4jruby'

 class MyClass
   enable_logger

   class << self
     def my_class_method
       logger.info("hello from class method")
     end
   end

   def my_method
     logger.info("hello from instance method")
   end
 end

Custom logger name

logger = Log4jruby::Logger.get('my.logger')
logger.debug('something')

Log4jruby logger names are prefixed with .jruby.

e.g. log4j.properties

 ...
 log4j.logger.jruby=info,Console
 log4j.logger.jruby.MyClass=debug
 log4j.logger.jruby.my.logger=error

Inclusion of filename, line number, and method name in log messages via MDC

e.g.

log4j.appender.Ruby.layout.ConversionPattern=%5p %.50X{fileName} %X{methodName}:%X{lineNumber} - %m%n

enable tracing globally

Log4jruby::Logger.root.tracing = true

or for specific logger

Log4jruby::Logger.get('MyClass', tracing: true)

produces log statements like:

DEBUG jruby.MyClass foo:17 - hello from foo

Exceptions are logged with backtraces

$ ruby ./examples/nested_ruby_exceptions.rb 
RuntimeError: raised from foo
     foo at ./examples/nested_ruby_exceptions.rb:13
  <main> at ./examples/nested_ruby_exceptions.rb:26
RuntimeError: raised from bar
     bar at ./examples/nested_ruby_exceptions.rb:19
     foo at ./examples/nested_ruby_exceptions.rb:11
  <main> at ./examples/nested_ruby_exceptions.rb:26
RuntimeError: raised from baz
     baz at ./examples/nested_ruby_exceptions.rb:23
     bar at ./examples/nested_ruby_exceptions.rb:17
     foo at ./examples/nested_ruby_exceptions.rb:11
  <main> at ./examples/nested_ruby_exceptions.rb:26

logger.warn(exception)

logger.warn { exception }

Some Log4j Logger compatible signatures addded.

logger.log_error(msg, exception)

See more in log4jruby/examples.

Configuration

Configuring log4j is left to the client via the standard log4j configuration process.

E.g.

Create a log4j.properties file and make sure it is available in your classpath.

The log4j 1.2 jar must be found in your classpath when log4jruby is loaded.

• Place files somewhere already in your classpath such as $TOMCAT/lib for Tomcat.
• Configure classpath via JAVA_OPTS
• Amend $CLASSPATH at runtime before loading log4jruby. See examples/setup.rb.

Note: If you're using bundler, you can specify gem 'log4jruby', require: false in your Gemfile to delay loading the gem too early.

In a Rails application, add the following in config/application.rb or the appropriate config/environments file.

 config.logger = ActiveSupport::TaggedLogging.new(Log4jruby::Logger.get('MyApp'))

or older versions of Rails

 config.logger = Log4jruby::Logger.get('MyApp')

Development

Install log4j for tests and examples

rake dev:java_deps