Fear of Fish

I’ll be at RailsConf this week giving a talk for Engine Yard with other members of the team holding a Q & A after it. Come along and heckle us with difficult questions, or just watch. Quite a few of us will be at the #caboose conf meets as well, so if you’re there I look forward to seeing you!

Let’s pretend that you’re busy making a kick ass template maker, and you’d like to keep backups of the file you generate. You certainly don’t want to write over it every time, in case there’s customer changes that have been made since the last time you did. What if you want to keep 5 copies of it, and only 5?

Rather than code it all yourself, save yourself some trouble and download the Backup gem off github, and you’re ready to go:

Install

  $ sudo gem sources -a http://gems.github.com
  $ sudo gem install engineyard-backup

You only need to install the source once and then you can install any gem hosted on github, which basically means any repository that has a .gemspec at the root of their repository.

Usage

  backup = Backup.new("/the/file/to/backup")
  backup.run

So what exactly have we done here? Well, we’ve made a copy of the file we wanted backed up, and we’ve added a timestamp to it. Every time we run this file, Backup will move the current file to a timestamped version, and also ensure that (by default) 5 versions of that file are kept.

Want a different number of ‘releases’?

  # Set a different amount of backups on initialize
  backup = Backup.new("/the/file/to/backup", 10)
  # or set it manually
  backup.backups = 15
  # Run the backup
  backup.run

Some more methods:

  backup = Backup.new("/the/file/to/backup")
 
  # which files would we keep in a backup
  backup.keep_list
  # => ["backup.20080430185243", "backup.20080430185246", "backup.20080430185243", "backup.20080430185250", "backup.20080430185254"]
 
  # which files would we delete in a backup
  backup.delete_list
  # => ["backup.20080430185221", "backup.20080430185224", "backup.20080430185230"]
 
  # how about skipping the cleanup?
  backup.run( :no_delete )
 
  # what if we just want to cleanup the old revisions
  backup.cleanup
 
  # and finally, how about we just get a list of the backup files present
  backup.find_all_releases

Notes

This library doesn’t care where it’s being used, it could be a Rails application or a command line Ruby script of some sort. It merely handles backups of files in the form of a library. If you just want to backup some files and not programmatically from within your own application, then these are not the droids you are looking for.

Conclusion

Easy peasy, lemon squeezy backups. Enjoy.