How to add a custom log level to logger in ruby?

Question

I need to add a custom log level like "verbose" or "traffic" to ruby logger, how to do?

Answer 1

Your own logger just need to overwrite the Logger#format_severity method, something like this :

class MyLogger < Logger

  SEVS = %w(DEBUG INFO WARN ERROR FATAL VERBOSE TRAFFIC)
  def format_severity(severity)
    SEVS[severity] || 'ANY'
  end

  def verbose(progname = nil, &block)
    add(5, nil, progname, &block)
  end
end

Answer 2

You can simply add to the Logger class:

require 'logger'

class Logger
  def self.custom_level(tag)
    SEV_LABEL << tag 
    idx = SEV_LABEL.size - 1 

    define_method(tag.downcase.gsub(/\W+/, '_').to_sym) do |progname, &block|
      add(idx, nil, progname, &block)
    end 
  end 

  # now add levels like this:

  custom_level 'TRAFFIC'
  custom_level 'ANOTHER-TAG'
end


# using it:

log = Logger.new($stdout)
log.traffic('testing')
log.another_tag('another message here.')

Answer 3

Log levels are nothing but integer constants defined in logger.rb:

# Logging severity.
module Severity
  DEBUG = 0
  INFO = 1
  WARN = 2
  ERROR = 3
  FATAL = 4
  UNKNOWN = 5
end

You can log messages with any level you like using Logger#add method:

l.add 6, 'asd'
#=> A, [2010-02-17T16:25:47.763708 #14962]   ANY -- : asd