Nice colorized logs for Rails apps! With this initializer, you can instantly colorize your Rails development logs. Just copy and paste the code, and it’ll work. https://x.com/kyrylosilin/status/1852308566201237815

colorized_logger.rb

# frozen_string_literal: true
# config/initializers/colorized_logger.rb

# This initializer adds color to the Rails logger output. It's a nice way to
# visually distinguish log levels.
module ColorizedLogger
  COLOR_CODES = {
    debug:   "\e[36m",  # Cyan
    info:    "\e[32m",  # Green
    warn:    "\e[33m",  # Yellow
    error:   "\e[31m",  # Red
    fatal:   "\e[35m",  # Magenta
    unknown: "\e[37m"   # White (or terminal default)
  }.freeze

  RESET = "\e[0m"

  def debug(progname = nil, &block)
    super(colorize(:debug, progname, &block))
  end

  def info(progname = nil, &block)
    super(colorize(:info, progname, &block))
  end

  def warn(progname = nil, &block)
    super(colorize(:warn, progname, &block))
  end

  def error(progname = nil, &block)
    super(colorize(:error, progname, &block))
  end

  def fatal(progname = nil, &block)
    super(colorize(:fatal, progname, &block))
  end

  def unknown(progname = nil, &block)
    super(colorize(:unknown, progname, &block))
  end

  private

  def colorize(level, message, &block)
    "#{COLOR_CODES[level]}#{message || (block && block.call)}#{RESET}"
  end
end

Rails.logger.extend(ColorizedLogger)

What’s great about it is that you can use the default Rails logger as you normally would. For example, if you want to log an error, just use Rails.logger.error("there was a problem"), and it will print the message in red.

Thanks for the tip, i changed it a bit, but remains the same in terms of features.

# frozen_string_literal: true
module ColorizedLogger
  RESET = "\e[0m"
  COLOR_CODES = {
    unknown: RESET, # Terminal default
    debug: "\e[0;36m", # Cyan text
    info: "\e[0;32m", # Green text
    warn: "\e[1;33m", # Yellow text
    error: "\e[1;31m", # Red text
    fatal: "\e[1;31m", # Bold Red text
  }.freeze
  %i[debug info warn error fatal unknown].each do |level|
    define_method(level) { |progname = nil, &block| super(colorize_message(level, progname || (block && block.call))) }
  end
  private
  def colorize_message(level, message)
    "#{COLOR_CODES[level]}#{message}#{RESET}"
  end
end
Rails.logger.extend(ColorizedLogger)

@navidemad If you like code golfing, here's an even shorter version:

# frozen_string_literal: true
module ColorizedLogger
  %i[debug info warn error fatal unknown].each do |level|
    color = case level
            when :debug then "\e[0;36m"  # Cyan text
            when :info  then "\e[0;32m"  # Green text
            when :warn  then "\e[1;33m"  # Yellow text
            when :error, :fatal then "\e[1;31m"  # Red text
            else "\e[0m"  # Terminal default
            end
    
    define_method(level) do |progname = nil, &block| 
      super(color + (progname || (block && block.call)).to_s + "\e[0m")
    end
  end
end
Rails.logger.extend(ColorizedLogger)