logging - How can I have ruby logger log output to stdout as well as file?

Question

Someting like a tee functionality in logger.

Answer 1

You can write a pseudo IO class that will write to multiple IO objects. Something like:

class MultiIO
  def initialize(*targets)
     @targets = targets
  end

  def write(*args)
    @targets.each {|t| t.write(*args)}
  end

  def close
    @targets.each(&:close)
  end
end

Then set that as your log file:

log_file = File.open("log/debug.log", "a")
Logger.new MultiIO.new(STDOUT, log_file)

Every time Logger calls puts on your MultiIO object, it will write to both STDOUT and your log file.

Edit: I went ahead and figured out the rest of the interface. A log device must respond to write and close (not puts). As long as MultiIO responds to those and proxies them to the real IO objects, this should work.