rotate.rb

#!/usr/bin/env ruby

require 'date'
require 'syslog'
require 'fileutils'

bkup_dir = ARGV.first

log = Syslog.open($0, Syslog::LOG_PID | Syslog::LOG_CONS)
log.info "Starting backup rotation for #{bkup_dir}"

def get_days(day = Date.today, days = 7)
  if day.class != Array
    get_days(Array(day))
  else
    if day.length == days
      day
    else
      get_days day.push(day.last.prev_day)
    end
  end
end

def get_weeks(day = Date.today, weeks = 6)
  until day.sunday?
    day = day.prev_day
  end
  
  sundays = Array(day)
  (weeks - 1).times do
    sundays.push sundays.last.prev_day(7)
  end

  sundays
end

def get_first_sunday(day = Date.today, months_ago = 0)
  mons_ago = day.prev_month(months_ago)
  start_of_month = mons_ago.prev_day(mons_ago.mday - 1)
  until start_of_month.sunday?
    start_of_month = start_of_month.next_day
  end

  start_of_month
end

def get_months(day = Date.today, months = 6)
  if day < get_first_sunday(day)
    first_ofs = Array(get_first_sunday(day, 1))
  else
    first_ofs = Array(get_first_sunday(day))
    months -= 1
  end

  months.times do
    first_ofs.push get_first_sunday(first_ofs.last, 1)
  end

  first_ofs
end

backups = {
  :daily => get_days,
  :weekly => get_weeks,
  :monthly => get_months
}

def before_cutover?(date)
  date < Date.parse("20130807")
end

Dir.glob("#{bkup_dir}/*").each do |backup|
  file_name = File.basename(backup)
  bkup_date = Date.parse(file_name.gsub!(/(weekly|monthly|daily)-/, ""))

  if backups[:monthly].include? bkup_date
    if file_name =~ /monthly/
      log.info "found monthly backup: #{file_name}"
    elsif before_cutover? bkup_date
      if bkup_date < Date.today.prev_month(6)
        log.info "Deleting file: #{backup}"
        FileUtils.rm_rf(backup)
      end
    else
      log.info "Renaming file: #{file_name}"
      File.rename(backup, backup.gsub(/(weekly|daily)/, "monthly"))
    end
  elsif backups[:weekly].include? bkup_date
    if file_name =~ /weekly/
      log.info "found weekly backup: #{file_name}"
    elsif before_cutover? bkup_date
      if bkup_date < Date.today.prev_day(7 * 6)
        log.info "Deleting file: #{backup}"
        FileUtils.rm_rf(backup)
      end
    else
      log.info "Renaming file: #{file_name}"
      File.rename(backup, backup.gsub(/(monthly|daily)/, "monthly"))
    end
  elsif backups[:daily].include? bkup_date
    log.info "Found daily backup: #{backup}"
  elsif before_cutover? bkup_date
    if bkup_date < Date.today.prev_day(7)
      log.info "Deleting file: #{backup}"
      FileUtils.rm_rf(backup)
    end
  else
    log.info "Deleting file: #{backup}"
    FileUtils.rm_rf(backup)
  end
end