Nov 4, 2017

Microservices: Ubuntu Core and snap - a minimal linux

After some first steps with coreOS
i read about Ubuntu Core, which targets also on a minimal linux. Here an architecture overview from ubuntu:
Ubuntu provides an image for KVM (the link points to an installation howto), but i want to stay with Virtualbox. I followed this tutorial:
unxz ubuntu-core-16-amd64.img.xz
VBoxManage convertdd ubuntu-core-16-amd64.img ubuntu-core-16-amd64.vdi --format VDI

VBoxManage modifyhd ubuntu-core-16-amd64.vdi --resize 20480
And then configure the virtualbox vm:

And Go!

To pass this step you have to create an account at
 At you have to provide your public ssh keyfile:

and then a login which does not work:

and the login via ssh:

schroff@zerberus:~$ ssh d-schroff@
The authenticity of host ' (' can't be established.
ECDSA key fingerprint is SHA256:yKE/g7JYnlED6jOF/8gsUeVrdkuEU/zytFdlCcVzNEs.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '' (ECDSA) to the list of known hosts.
Welcome to Ubuntu 16.04.1 LTS (GNU/Linux 4.4.0-45-generic x86_64)

 * Documentation:
 * Management:
 * Support:

The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

Welcome to Snappy Ubuntu Core, a transactionally updated Ubuntu.

 * See

It's a brave new world here in Snappy Ubuntu Core! This machine
does not use apt-get or deb packages. Please see 'snap --help'
for app installation and transactional updates.

First impression: Getting a ssh login is much easier than configuring ssh with ignition at coreOS.

If you want to learn how to install and run a webserver with snap, take a look here.
This posting will show, how to build your own application into a snap.

Other posts around this topic: Snapcraft / Snap on ubuntu core

  • Installing Ubuntu Core on Virtualbox
  • Creating a snap containing only a shell script
  • Running a webserver (caddy) with snap
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