Update: Folsom instructions
jclouds is a popular cross-cloud toolkit that covers an impressive number of public and private cloud providers. OpenStack is among these providers and the OpenStack ecosystem benefits from good support in jclouds because it allows developers who are comfortable with Java or jclouds to easily adopt OpenStack and it enables hybrid cloud development. Likewise, jclouds benefits from good OpenStack support because OpenStack is a popular Infrastructure as a Service provider and already has deep roots in the open source community.
A number of times on the jclouds-dev mailing list and IRC I've seen developers who want to help contribute OpenStack support to jclouds but aren't entirely sure about how to go about it. There are a number of things you need to get started.
- A jclouds development environment
- Some background on jclouds development
- An OpenStack test environment
jclouds dev env
To setup a jclouds development environment start at their Developer Resources page. From there the most relevant page is Contributing to the jclouds Code Base. If you're an Eclipse user, you'll want to check out Using Eclipse. Learning about Testing in jclouds is essential and the Additional References and Guides for Advanced Users also contains a wealth of design and implementation documentation. You might also want to browse through the jclouds-dev mailing list.
jclouds dev background
The foundation of jclouds is built upon Google's general purpose library Guava and their lightweight dependency injection framework Guice. You don't necessarily have to know these to start contributing but being aware of it and having the reference documentation on hand will be helpful. To talk to OpenStack's RESTful web services jclouds uses the Java API for RESTful Web Services (JAX-RS).
For those unfamiliar with setting up an OpenStack dev/test env this can be a daunting task. There are a number of ways to do it and often it boils down to a developer's preference on how they want to deploy it...so I'll share my personal preference. :)
My OpenStack test env consists of VirtualBox running an Ubuntu 12.04 Server (Precise Pangolin) virtual machine with devstack. This guide assumes you're comfortable installing Ubuntu on VirtualBox and know your way around the command line and git.
- Download and install VirtualBox
- The networking can be a bit tricky and I've already addressed this in the ServerFault question What is the correct network configuration for a devStack VM (virtualbox)?
- Download the 64-bit PC (AMD64) server install CD of Ubuntu 12.04 and create a VirtualBox VM with it
- Once it's ready to go you should be able to login to it from your terminal
- Once logged in, take a break, and have a look at the instructions for devstack
- If you want a release branch of OpenStack (e.g. Essex, Folsom, etc.), you need to do things a little differently
- If you want the latest and greatest master branch of OpenStack, in the devstack/ directory, create a localrc file like this
- In both cases
- Change to your devstack directory
- Run stack.sh
- When it completes, configure Keystone to return the VM's "public" IP
sed -i "s#publicURL = http://10.0.2.15#publicURL = http://172.16.0.1#g" /etc/keystone/default_catalog.templates
mysql -uroot -pdevstack keystone
update endpoint set extra = replace(extra, '"publicurl": "[http://10.0.2.15](http://10.0.2.15/)', '"publicurl": "[http://172.16.0.1](http://172.16.0.1/)') where instr(extra, '"publicurl": "[http://10.0.2.15](http://10.0.2.15/)') > 0;
- Kill the existing screen session (that contains all of the OpenStack services)
screen -X -S stack quit
- Restart screen (with all of the OpenStack services)
screen -c stack-screenrc
- Outside of the VM, back on your local machine, you should now be able to follow the instructions in my post jclouds and OpenStack to verify that everything is working as expected
- Once you've verified it's working, then port the jclouds and OpenStack example into your jclouds dev env and go from there
Clearly it's non-trivial to get a full development/test environment like this up and running. However, the benefits are a healthier OpenStack ecosystem that's inclusive of the many Java developers around the world.
This post was written on Mac OS X 10.7.4, Java 1.6.0, jclouds 1.5.1, and OpenStack Essex/master.