This script will clean out old capistrano releases from a set of subdirectories, but will keep a minimum number. It's designed to be run as a cron job.

clean_up_old_releases.rb

#!/usr/bin/env ruby

# This script will clean out old capistrano releases from a set of
# subdirectories, but will keep a minimum number. It's designed to be run as
# a cron job.
#
# (c) Copyright 2008 West Arete Computing, Inc.

require 'date'
require 'fileutils'

# Clean out all the old releases, keeping a handful of recent ones.
def clean_up_old_releases
  Dir.glob("/var/www/sites/*/releases").each do |release_dir|
    # Get all the entries that look like a release
    releases = Dir.entries(release_dir).select { |f| is_release?(f) }
    # Always keep a few of the most recent releases
    releases -= releases.sort.last(5)
    # Remove any that are getting old
    releases.select { |release| is_old?(release) }.each do |release|
      full_path = File.join(release_dir, release)
      puts "Removing #{full_path}"
      FileUtils.remove_dir(full_path, true)
    end
  end
end

# Returns true if the given filename looks like a release.
def is_release?(filename)
  filename =~ /^\d{14}$/
end

# Returns true if the given release directory looks too old to keep.
def is_old?(filename)
  filename < release_name(Date.today - 30)
end

# Return the same format for the given time object that capistrano uses to
# name its release directories.
def release_name(time)
  time.strftime("%Y%m%d%H%M%S")
end

# Actually perform the cleanup if this script is being run directly.
clean_up_old_releases if File.basename($0) == File.basename(__FILE__)