It's a Snap!

A couple of months ago, I re-introduced an old friend -- Ubuntu JeOS (Just enough OS) -- the smallest, (merely 63MB compressed!) functional OS image that we can still call “Ubuntu”.  In fact, we call it Ubuntu Core.

That post was a prelude to something we’ve been actively developing at Canonical for most of 2014 -- Snappy Ubuntu Core!  Snappy Ubuntu combines the best of the ground-breaking image-based Ubuntu remix known as Ubuntu Touch for phones and tablets with the base Ubuntu server operating system trusted by millions of instances in the cloud.

Snappy introduces transactional updates and atomic, image based workflows -- old ideas implemented in databases for decades -- adapted to Ubuntu cloud and server ecosystems for the emerging cloud design patterns known as microservice architectures.

The underlying, base operating system is a very lean Ubuntu Core installation, running on a read-only system partition, much like your iOS, Android, or Ubuntu phone.  One or more “frameworks” can be installed through the snappy command, which is an adaptation of the click packaging system we developed for the Ubuntu Phone.  Perhaps the best sample framework is Docker.  Applications are also packaged and installed using snappy, but apps run within frameworks.  This means that any of the thousands of Docker images available in DockerHub are trivially installable as snap packages, running on the Docker framework in Snappy Ubuntu.

Take Snappy for a Drive

You can try Snappy for yourself in minutes!

You can download Snappy and launch it in a local virtual machine like this:

$ wget http://cdimage.ubuntu.com/ubuntu-core/preview/ubuntu-core-alpha-01.img
$ kvm -m 512 -redir :2222::22 -redir :4443::443 ubuntu-core-alpha-01.img

Then, SSH into it with password 'ubuntu':

$ ssh -p 2222 ubuntu@localhost

At this point, you might want to poke around the system.  Take a look at the mount points, and perhaps try to touch or modify some files.

$ sudo rm /sbin/init
rm: cannot remove ‘/sbin/init’: Permission denied
$ sudo touch /foo

touch: cannot touch ‘foo’: Permission denied
$ apt-get install docker
apt-get: command not found

Rather, let's have a look at the new snappy package manager:

$ sudo snappy --help

And now, let’s install the Docker framework:

$ sudo snappy install docker

At this point, we can do essentially anything available in the Docker ecosystem!

Now, we’ve created some sample Snappy apps using existing Docker containers.  For one example, let’s now install OwnCloud:

$ sudo snappy install owncloud

This will take a little while to install, but eventually, you can point a browser at your own private OwnCloud image, running within a Docker container, on your brand new Ubuntu Snappy system.

We can also update the entire system with a simple command and a reboot:

$ sudo snappy versions

$ sudo snappy update
$ sudo reboot

And we can rollback to the previous version!

$ sudo snappy rollback
$ sudo reboot

Here's a short screencast of all of the above...

While the downloadable image is available for your local testing today, you will very soon be able to launch Snappy Ubuntu instances in your favorite public (Azure, GCE, AWS) and private clouds (OpenStack).

Enjoy!
Dustin