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Gstack, a GCE compatible interface to CloudStack

Google Compute Engine (GCE) is the Google public cloud. In december 2013, Google announced the General Availability (GA) of GCE. With AWS and Microsoft Azure, it is one of the three leading public clouds in the market. Apache CloudStack now has a brand new GCE compatible interface (Gstack) that lets users use the GCE clients (i.e gcloud and gcutil) to access their CloudStack cloud. This has been made possible through the Google Summer of Code program.

Last summer Ian Duffy, a student from Dublin City University participated in GSoC through the Apache Software Foundation (ASF) and worked on a LDAP plugin to CloudStack. He did such a great job that he finished early and was made an Apache CloudStack committer. Since he was done with his original GSoC project I encouraged him to take on a new one :), he brought in a friend for the ride: Darren Brogan. Both of them worked for fun on the GCE interface to CloudStack and learned Python doing so.

They remained engaged with the CloudStack community and has a third year project worked on an Amazon EC2 interface to CloudStack using what they learned from the GCE interface. They got an A :). Since they loved it so much, Darren applied to the GSoC program and proposed to go back to Gstack, improve it, extend the unittests and make it compatible with the GCE v1 API.

Technically, Gstack is a Python Flask application that provides a REST API compatible with the GCE API and forwards the requests to the corresponding CloudStack API. The source is available on GitHub and the binary is downloadable via PyPi. Let's show you how to use it.

Installation and Configuration of Gstack

You can grab the Gstack binary package from Pypi using pip in one single command.

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Eutester with CloudStack

Posted by on in CloudStack Tips


An interesting tool based on Boto is Eutester it was created by the folks at Eucalyptus to provide a framework to create functional tests for AWS zones and Eucalyptus based clouds. What is interesting with eutester is that it could be used to compare the AWS compatibility of multiple clouds. Therefore the interesting question that you are going to ask is: Can we use Eutester with CloudStack ? And the answer is Yes. Certainly it could use more work but the basic functionality is there.

Install eutester with:

pip install eutester

Then start Python/iPython interactive shell or write a script that will import ec2ops and create a connection object to your AWS EC2 compatible endpoint. For example, using ec2stack:

    #!/usr/bin/env python

    from eucaops import ec2ops
    from IPython.terminal.embed import InteractiveShellEmbed

    accesskey="my api key"
    secretkey="my secret key"


    ipshell = InteractiveShellEmbed(banner1="Hello Cloud Shell !!")

Eutester at the time of this writing has 145 methods. Only the methods available through the CloudStack AWS EC2 interface will be availble. For example, get_zones and get_instances would return:

In [3]: conn.get_zones()
Out[3]: [u'ch-gva-2']

In [4]: conn.get_instances()
[2014-05-21 05:39:45,094] [EUTESTER] [DEBUG]: 
--->( method: get_instances(self, state=None, 
     idstring=None, reservation=None, rootdevtype=None, zone=None,
     key=None, pubip=None, privip=None, ramdisk=None, kernel=None,
     image_id=None, filters=None)

This example shows that I am running eight instances at the moment in a zone called ch-gva-2, our familiar exoscale. Selecting one of these instance objects will give you access to all the methods available for instances. You could also list, delete and create keypairs. List, delete and create security groups etc.

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Migration from Publican to Sphinx and Read The Docs

When we started with Cloudstack we chose to use publican for our documentation. I don't actually know why, except that Red Hat documentation is entirely based on publican. Perhaps David Nalley's background with Fedora influenced us :) In any case publican is a very nice documentation building system, it is based on the docbook format and has great support for localization. However it can become difficult to read and organize lots of content, and builds may break for strange reasons. We also noticed that we were not getting many contributors to the documentation, in contrast, the translation efforts via transifex has had over 80 contributors. As more features got added to CloudStack the quality of the content also started to suffer and we also faced issues with publishing the translated documents. We needed to do something, mainly making it easier to contribute to our documentation. Enters ReStructured Text (RST) and Read The Docs (RTD).

Choosing a new format

We started thinking about how to make our documentation easier to contribute to. Looking at Docbook, purely xml based, it is a powerful format but not very developer friendly. A lot of us are happy with basic text editor, with some old farts like me mainly stuck with vi. Markdown has certainly helped a lot of folks in writing documentation and READMEs, just look at Github projects. I started writing in Markdown and my production in terms of documentation and tutorials skyrocketed, it is just a great way to write docs. Restructured Text is another alternative, not really markdown, but pretty close. I got familiar with RST in the Apache libcloud project and fell in love with it, or at least liked it way more than docbook. RST is basically text, only a few markups to learn and your off.

Publishing Platform

A new format is one thing but you then need to build documentation in multiple formats: html, pdf, epub potentially more. How do you move from .rst to these formats for your projects ? Comes in Sphinx, pretty much an equivalent to publican originally aimed at Python documentation but now aimed at much more. Installing sphinx is easy, for instance on Debian/Ubuntu:

apt-get install python-sphinx

You will then have the sphinx-quickstart command in your path, use it to create your sphinx project, add content in index.rst and build the docs with make html. Below is a basic example for a ff sample project.


What really got me sold on reStructuredText and Sphinx was ReadTheDocs (RTD). It hosts documentation for open source projects. It automatically pulls your documentation from your revision control system and builds the docs. The killer feature for me was the integration with github (not just git). Using hooks, RTD can trigger builds on every commit and it also displays an edit on github icon on each documentation page. Click on this icon, and the docs repository will get forked automatically on your github account. This means that people can edit the docs straight up in the github UI and submit pull requests as they read the docs and find issues.

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New EC2 interface to CloudStack

Posted by on in Cloud News


CloudStack features an EC2 query interface that can be run on the management server. This is great, but written in Java and using axis can be a bit difficult to hack on and improve. EC2stack is a new project by CloudStack committer Ian Duffy and a buddy of his Darren Brogan from Dublin City University. They did this as part of their third year school project. Building on their previous experience with gstack, a GCE interface to CloudStack, they wrote a brand new EC2 interface to CloudStack.

The interface uses Flask microframework and is written 100% in Python. It also features a vagrant box for easy testing, lots of unittests and automatic build tests (pep8, pylint and coverage) via Travis CI. All around a pretty tight project. They did it on github and not directy in the Apache CloudStack trunk because it was a graded project. They did get permission to put it on github but could not accept pull requests :)

Getting Started with the vagrant box

Clone the repo and launch the vagrant box:

git clone
cd ec2stack
vagrant up

Within the VM you can now configure ec2stack:

mkvirtualenv ec2stack
cd /vagrant
python develop

Getting Started without vagrant

Just install ec2stack with:

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I was at CloudExpo Europe in London last week for the Open Cloud Forum to give a tutorial on CloudStack tools. A decent crowd showed up, all carrying phones. Kind of problematic for a tutorial where I wanted the audience to install python packages and actually work :) Luckily I made it self-paced so you can follow at home. Giles from Shapeblue was there too and he was part of a panel on Open Cloud. He was told once again "But Apache CloudStack is a Citrix project !" This in itself is a paradox and as @jzb told me on twitter yesterday "Citrix donated CloudStack to Apache, the end". Apache projects do not have any company affiliation.

I don't blame folks, with all the vendors seemingly supporting OpenStack, it does seem that CloudStack is a one supporter project. The commit stats are also pretty clear with 39% of commits coming from Citrix. This number is also probably higher since those stats are reporting gmail and apache as domain contributing 20 and 15% respectively, let's say 60% is from Citrix. But nonetheless, this is ignoring and mis-understanding what Apache is and looking at the glass half empty.

When Citrix donated CloudStack to the Apache Software Foundation (ASF) it relinquished control of the software and the brand. This actually put Citrix in a bind, not being able to easily promote the CloudStack project. Indeed, CloudStack is now a trademark of the ASF and Citrix had to rename their own product CloudPlatform (powered by Apache CloudStack). Citrix cannot promote CloudStack directly, it needs to get approval to donate sponsoring and follow the ASF trademark guidelines. Every committer and especially PMC members of Apache CloudStack are now supposed to work and protect the CloudStack brand as part of the ASF and make sure that any confusion is cleared. This is what I am doing here.

Of course when the software was donated, an initial set of committers was defined, all from Citrix and mostly from the former startup. Part of the incubating process at the ASF is to make sure that we can add committers from other organization and attract a community. "Community over Code" is the bread and butter of ASF and so this is what we have all been working on, expanding the community outside Citrix, welcoming anyone who thinks CloudStack is interesting enough to contribute a little bit of time and effort. Looking at the glass half empty is saying that CloudStack is a Citrix project "Hey look 60% of their commits is from Citrix", looking at it half full like I do is saying "Oh wow, in a year since graduation, they have diversified the committer based, 40% are not from Citrix". Is 40% enough ? of course not, I wish it were the other way around, I wish Citrix were only a minority in the development of CloudStack.

Couple other numbers: Out of the 26 members of the project management committee (PMC) only seven are from Citrix and looking at mailing lists participation since the beginning of the year, 20% of the folks on the users mailing list and 25% on the developer list are from Citrix. We have diversified the community a great deal but the "hand-over", that moment when new community members are actually writing more code than the folks who started it, has not happened yet. A community is not just about writing code, but I will give it to you that it is not good for a single company to "control" 60% of the development, this is not where we/I want to be.

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Citrix supports the open source community via developer support and evangeslism. We have a number of developers and evangelists that participate actively in the open source community in Apache Cloudstack, OpenDaylight, Xen Project and XenServer. We also conduct educational activities via the Build A Cloud events held all over the world.