Integrating Log4r and Ruby on Rails

Aaaaaaaages ago, I wrote a message on the mailing list (before it moved to Google Groups!) about how to integrate Rails and Log4r. Since then a little bit has changed and that way may or may not entirely work any more. Since then, aaaaages ago Jason Rimmer asked me to update so that it’s all new and fresh, but I completely forgot in the move to the UK (very sorry Jason!). So here it is.

I’ve got a few outputters. One that acts like the default outputter, that writes “development.log” and so on. Then another that outputs to standard error for console lovin’ (in dev mode). Then another that uses a date file outputter to automatically roll over logs every day (for production mode), and finally an Email outputter that only runs in production and sends an email of the log for ERROR and FATAL log levels.

Log4r Rails configuration files

The first bit is the configuration YAML file, which is used to configure the loggers. Then there is logger.rb, which turns on and off the outputters as required. The final part is to include this logger.rb into the application configuration.

It is VERY IMPORTANT that you include the file before the call to the Rails::Initializer.run do block. This is because in this section of code the RAILS_DEFAULT_LOGGER is initialised, and if we don’t get in before that, we won’t get our logger injected into the Rails framework stack. So, configure it like this:

require File.join(File.dirname(__FILE__), 'boot')

require File.expand_path(File.dirname(__FILE__) + "/logger")

Rails::Initializer.run do |config|
...

Just drop the require line in there and it will load logger.rb, which loads log4r.yaml, and everything is up and going. You’ll see friendly [DEBUG] lines in your console and everthing! Of course, I prefer verbose logging on the console in development; you may not, customise by reading the log4r manual. Of course, if you expect your error mails to be delivered, change the SMTP server settings at the bottom of the yaml file.

Sorry for the delay Jason!