dumb_ass_backup.rb

#!/usr/bin/env ruby

# Dumb-ass backup - better than no backup!
#
# Run nightly and enjoy daily, weekly and monthly filesystem backups
#
# - default destination directory is /var/local/backup
# - latest, daily, weekly and monthly sub-directories are created
# - latest directory should only ever contain the latest backup
# - latest backup copied to daily, weekly and monthly directories as required
# - weekly backups created on Sunday
# - monthly backups created on first day of month
# - retains 7 daily, 4 weekly and 3 monthly backups
#
# TODO:
# - exit non-zero and output to stderr when external commands fail
# - allow retention policy to be configured
# - allow day of week for weekly to be configured
# - allow day of month for monthly to be configured
# - look into automagic inclusion of common directories into default sources
# - code cleanup, it's been hacked together to get something working
# - add option to provide path for config file (and ensure one exists)

require 'yaml'
require 'fileutils'

# Use full paths to system commands to avoid probles with aliases etc.
whoami = `which whoami`.chomp
tar = `which tar`.chomp

# Must be root to ensure backup archives contain expected files
if `#{whoami}`.chomp != "root"
  puts "Error: You must be root to run this script"
  exit 1
end

config = File.exist?("/usr/local/etc/dumb_ass_backup.yml") ? YAML::load_file("/usr/local/etc/dumb_ass_backup.yml") : {}

sources = config['sources'] || {
  "etc" => "/etc/"
}

destination = config['destination'] || "/var/local/backup"

puts "\nBackup started: #{Time.now}"

puts "\nDestination: #{destination}"

# Make sure sub-directories exist
%w{ latest daily weekly monthly }.each do |name|
  FileUtils.mkdir_p File.join(destination, name)
end

# Delete any old backups from latest directory
Dir.glob(File.join(destination, "latest", "*")).each do |file|
  FileUtils.rm_rf file
end

today = Time.now.strftime('%Y-%m-%d')
latest_path = File.join(destination, "latest", today)

puts "\nBacking up files"
sources.each do |name, glob_pattern|

  backup_path = File.join(latest_path, name)
  FileUtils.mkdir_p(backup_path)

  Dir.glob(glob_pattern).each do |source_path|

    print "* #{File.basename(source_path)} -> "
    if File.directory?(source_path)
      # tar and gzip directories, following symlinks
      target_path = File.join(backup_path, "#{File.basename(source_path)}.tar.gz")
      system("#{tar} -chz \"#{source_path}\" > \"#{target_path}\" 2> /dev/null")
      raise "Failed to create archive #{target_path}" unless File.exist?(target_path)
      # To preserve file permissions, only allow root to extract archives
      FileUtils.chmod(0600, target_path)
    else
      # copy files, preserving permissions
      target_path = File.join(backup_path, File.basename(source_path))
      FileUtils.cp_r(source_path, target_path, :preserve => true)
    end

    relative_target_path = target_path.sub(destination,'').sub(/^\//,'')
    print "#{relative_target_path}\n"

  end

end

puts "\nCreating copies"
do_weekly = Time.now.wday == 0
do_monthly = Time.now.mday == 1

%w{ daily weekly monthly }.each do |name|
  print "* Creating #{name} copy..."
  if (name == "weekly" && !do_weekly) || (name == "monthly" && !do_monthly)
    print "n/a\n"
    next
  end

  target_path = File.join(destination, name)
  FileUtils.cp_r(latest_path, target_path, :preserve => true)

  if File.exist?(File.join(target_path, today))
    print "OK\n"
  else
    print "FAIL\n"
    exit 1
  end
end

puts "\nApplying retention policy"
keep_daily = 7
keep_weekly = 4
keep_monthly = 3

%w{ daily weekly monthly }.each do |name|
  keep_count = eval("keep_#{name}")
  print "* Keeping #{keep_count} #{name} backups..."

  target_path = File.join(destination, name)

  list_backups = Proc.new do
    Dir.glob(File.join(target_path, "*")).select{|file|
      file.match(/\d{4}-\d{2}-\d{2}$/)
    }.sort
  end

  backups_before = list_backups.call
  backups_to_keep = backups_before.reverse.slice(0,keep_count)
  backups_to_delete = backups_before - backups_to_keep

  if backups_to_delete.empty?
    print "OK\n"
    next
  end

  backups_to_delete.each do |backup|
    FileUtils.rm_rf(backup)
  end

  backups_after = list_backups.call
  if backups_after.size == keep_count
    print "OK\n"
  else
    print "FAIL\n"
    exit 1
  end
end

puts "\nVerifying destination"

%w{ latest daily weekly monthly }.each do |name|
  print "* #{name} -> "

  target_path = File.join(destination, name)

  print Dir.entries(target_path).select{ |file|
    file.match(/\d{4}-\d{2}-\d{2}$/)
  }.sort.reverse.join(", ")

  print "\n"

end

puts "\nBackup completed: #{Time.now}"