Experiment with coloring and filtering stdout for a capistrano+chef project.

hijack_stdout.rb

#!/usr/bin/env ruby
require 'capistrano/cli'
require 'term/ansicolor'
include Term::ANSIColor

#
# This might get a real CLI at some point
#
puts "Target hosts: %s\nRecipes: %s\n" % [ENV['HOSTS'], ENV['RECIPES']]

#
# Hook into stdout for syntax highlighting and
# content filtering.
#
$stdout.instance_eval do
  alias __original_puts__ puts

  def puts *argv
    filtered = argv.map {|string| filter string }.compact
    __original_puts__ *filtered  unless filtered.empty?
  end

  alias __original_write__ write

  def write string
    if filtered = filter(string)
      __original_write__  filtered
    end
  end

  #
  # Colorize and filter output.
  #
  # Quick and dirty. It'll get cleaned up if this gets used.
  #
  def filter string
    case string
    when /.*(\[\d+\.\d+\.\d+\.\d+\]).*/
      string.sub $1, yellow($1)
    when /(.*)(INFO:)(.*)/
      string.sub $2, blue($2)
    when /^(\s+\* )executing "(.*)"/
      $1 + green($2) + "\n"
    when /command finished/, /executing command$/, /^\s*$/ then nil
    else string
    end
  end
end

cap_argv = %w[-p cook -l STDOUT]

Capistrano::CLI.parse(cap_argv).execute!