Rails 3.2.x: How to change logging levels without restarting the application

Question

I would like to change the logging levels of a running Rails 3.2.x application without restarting the application. My intent is to use it to do short-time debugging and information gathering before reverting it to the usual logging level.

I also understand that the levels in ascending order are debug, info, warn, error, and fatal, and that production servers log info and higher, while development logs debug and higher.

I understand that if I run

Rails.logger.level=:debug #or :info, :warn, :error, :fatal

Will this change the logging level immediately?

If so, can I do this by writing a Rake task to adjust the logging level, or do I need to support this by adding a route? For example in config/routes.rb:

match "/set_logging_level/:level/:secret" => "logcontroller#setlevel" 

and then setting the levels in the logcontroller. (:level is the logging level, and :secret which is shared between client and server, is something to prevent random users from tweaking the log levels)

Which is more appropriate, rake task or /set_logging_level?

Answer 1

In Rails console, you can simply do:

Rails.logger.level = :debug

Now all executed code will run with this log level

Answer 2

Why don't you use operating system signals for that? For example on UNIX user1 and user2 signals are free to use for your application:

config/initializers/signals.rb:

trap('USR1') do
  Rails.logger.level = Logger::DEBUG
end

trap('USR2') do
  Rails.logger.level = Logger::WARN
end

Then just do this:

kill -SIGUSR1 pid
kill -SIGUSR2 pid

Just make sure you dont override signals of your server - each server leverages various signals for things like log rotation, child process killing and terminating and so on.