Automatic system backups with backup gem and some shell scripting - part 2, using backup gem
In part 1 of this series we set up a remote image file as the backup storage, with some extra scripts for easier operations.
Now, let’s move on to actually backing up our data. To make this job real easy, let’s turn to the great ruby gem called, unsuprisingly, backup .
In the recently released version 3.5.0 of the gem, the installation has been streamlined significantly. If before that one had to install the gem, configure, than install all required dependencies with an extra command – now all you need to do is a single `gem install backup` command. It pulls in the gem itself, and all other gems it depends on – so just wait for it to finish, and you’re ready to go.
After that, you need to decide where to place the configuration files. By
default, they go into
~/Backup directory of the user that is performing the
backup – and that’s disctinctly not a Unix-like place for them to be, but
rather an OS X naming style. Still, it works, and for this tutorial we’ll
stick to the defaults here. If you want to change it – use
-c option when
running a backup operation, e.g.:
backup --perform mybackup -c /etc/backup
2.2. First backup model – database
The configuration of the backup gem is built around “models” – descriptions of the targets you’d like to backup, process, archive and store. In general, the backup process is split into the following phases:
- Creating archives of the current data (e.g. database data or files) as intermediate files.
- Packaging all archives together into a single tar file, and cleaning up all intermediate temp files when it’s done.
- Moving the package into its storage, and synchronizing the storage with an off-site location, if necessary.
- Sending out notifications.
It does sound like a lot of things to take care of, but backup gem makes it really easy by letting us build an initial model with a generator. Let’s say I want to back up MySQL database, store it in the filesystem, rotating 5 copies of latest backups in there, have it compressed with gzip, and be notified by email every time the backup is created. Easy! Let’s start by generating a model:
generate:model -t mysql_daily --storages="local" --compressors='gzip' --notifiers='mail' --databases='mysql' --no-splitter
If you run that, you should end up with an initial boilerplate model, that is very well commented, and can be used as a documentation of its own. Feel free to look around it and tinker with the details, and after some cleanup and changing the defaults you could end up with something like that:
# encoding: utf-8 Backup::Model.new(:mysql_daily, 'Daily mysql backup') do database MySQL do |db| db.name = :all db.username = "my_username" db.password = "my_password" db.host = "127.0.0.1" db.port = 3306 db.additional_options = ["--quick", "--single-transaction"] end store_with Local do |local| local.path = "~/storage/" local.keep = 5 end compress_with Gzip notify_by Mail do |mail| mail.on_success = true mail.on_warning = true mail.on_failure = true mail.delivery_method = :sendmail mail.to = "firstname.lastname@example.org" mail.from = "email@example.com" end end
And that’s it. With a single command and tinkering with some values, we ended
up with a fully specified backup configuration. Just pay attention to that
local.path parameter – remember that image file from
part 1 ,
that we’re mounting into our filesystem? That’s exactly where this backup is
supposed to go. I set the mount point of the image file to
before, so now I’m just pointing backup gem towards the same location. Make
sure you do the same.
Okay, enough talking, let’s run it:
backup perform -t mysql_daily
And if everything was correct – you should end up with a database dump, neatly packaged and named for further storage.
2.3. Second backup model – files
With the database backup set up, let’s move on to backing up essential local
files. I’m going to illustrate the concept using the backup of
of the server (which I personally prefer to back up as well), but the same
technique can be applied to your application’s data (e.g. uploaded files), and
everything else you have stored in the filesystem.
If you look again at the first backup model we created for the database, you could
notice that the only part that mentions the database at all is the first
database block. This is called, obviously, a database backup, but for
local files we’re going to use archive backup.
Let’s generate its model:
generate:model -t etc --storages="local" --compressors='gzip' --notifiers='mail' --databases='mysql' --no-splitter
You should end up with the model that looks similar to the one we have before,
but with an
archive block, instead of
database. For /etc files backup, we
could use the following configuration:
archive :etc do |archive| archive.use_sudo archive.add "/etc/" end
So – storing
/etc directory, and using sudo to run the archive command. Once
you’ve got past the basics of the gem operations – adding any amount of extra
stuff shouldn’t be a problem at all, and takes merely a minute.
Let’s do a test run of that as well:
backup perform -t etc
Hopefully, a backup of /etc is now staring right at you, and it’s time to automate the whole process.
2.4. Putting it all together – cron
Of course, we don’t want to log into the web server every day to run the backup. So let’s use the good old cron to run the task for us instead. Many modern Linux distributions are coming with cron set up to run hourly/daily/weekly tasks automatically based on scripts dropped into /etc/cron.daily, /etc/cron.weekly etc. So the actual process of scheduling the backup is as easy as just writing a very simple bash script to orchestrate the whole process.
Let’s recount the steps we have so far:
- Mount the backup image file under /home/backup/storage, using the script from part 1.
- Create new backup packages.
- Unmount the image.
We already wrote steps 1 and 3 in part 1, so let’s just build on top of that:
#!/bin/bash /etc/backup/backup-mount su - backup -c "cd ~ && backup perform --quiet -t etc,mysql_daily" /etc/backup/backup-umount
And that’s it. Put this file into /etc/cron.daily, and tomorrow you will wake up to a couple of emails about successfully completed backups.
2.5. Extra thoughts and tips
Using two separate backups models instead of a single model
One might ask – why can’t we put both
into the same backup model? Well, of course we can. But then we’ll end up with
the same package containing both database and file backups, and I personally
dislike it, as it forces me to deal with much more data when I need to
recover only a part of it. Having databases and files as two different models
results in their packages being stored in separate directories, with each
model’s name as its backup directory name, very neat and accessible.
If you prefer to have a single package – feel free to go that way, it will work just as well.
Keeping daily and weekly backups
I like to keep daily and weekly database backups. Usually, a week’s worth of daily backups, and about a month’s worth of weekly ones. While it’s always possible to just keep a 30 days of dailies, I find it being too much of a wasted disk space.
Doing daily/weekly split is very easy – just create another script (e.g. mysql_weekly), that is basically the same as the daily one, except for the different trigger name. And copy bash script orchestrating the backup into /etc/cron.weekly, changing it to invoke weekly backup, instead of a daily one.
Backup packages contain trigger names in them, so you’ll end up with dailies and weekly neatly separated into different directories, and you can configure different rotation cycles for them, if you want to.
You can’t go wrong with reading wiki pages for backup gem – if you’re going to read only two, make it Getting Started and Technical Overview . That, especially after you read this post, should give you enough understanding of gem’s workflows and operation basics.
Backing up huge file directories
Be careful with using
archive option for really huge directories (like 100s thousands of files) – remember that every backup will be a complete copy of the
directory, that will both take time to generate and disk space to store.
In the next post I’m going to show you a more efficient way to deal with huge number of files, by doing incremental backups with rsync and hardlinks. Stay tuned.