Amir Chaudhry

thoughts, comments & general ramblings

Unikernels for everyone!

Many people have now set up unikernels for blogs, documenting their experiences for others to follow. Even more important is that people are going beyond static sites to build unikernels that provide more complicated services and solve real-world problems.

To help newcomers get started, there are now even more posts that that use different tools and target different deployment methods. Below are summaries of some of the posts I found interesting and that will make it easier for you try out different ways of creating and deploying your unikernels.

Unikernel blogs with MirageOS

Mindy picked up where the first set of instructions finished and described her work to get an Octopress blog running on Amazon EC2. As one of the first people outside the core team to work on this, she had a lot of interesting experiences — which included getting into the Mirage networking stack to debug an issue and submit a bugfix! More recently, she also wrote a couple of excellent posts on why she uses a unikernel for her blog. These posts cover the security concerns (and responsibility) of running networked services on today’s Internet and the importance of owning your content — both ideas are at the heart of the work behind Nymote and are well worth reading.

Ian took a different path to AWS deployment by using Vagrant and Test Kitchen to to get his static site together and build his unikernel, and then Packer to create the images for deployment to EC2. All succinctly explained with code available on GitHub for others to try out!

Toby wanted to put together a blog that was a little more complicated than a traditional static site, with specific features like subdomains based on tags and the ability to set future dates for posts. He also pulled in some other libraries so he can use Mustache for sever-side rendering, where his blog posts and metadata are stored as JSON and rendered on request.

Chris saw others working to get unikernel blogs on EC2 and decide he’d try getting his up and running on Linode instead. He is the first person to deploy his unikernel to Linode and he provided a great walkthough with helpful screenshots, as well as brief notes about the handful of differences compared with EC2. Chris also wrote about the issue he had with clean urls (i.e serving /about/index.html when a user visits /about/) — he describes the things he tried out until he was finally able to fix it.

Phil focused on getting unikernels running on a cubieboards, which are ARM based development boards — similar to the Raspberry Pi. He starts by taking Mirage’s pre-built Cubieboard images — which makes it easy to get Xen and an OCaml environment set up on the board — and getting this installed on the Cubieboard. He also noted the issues he came across along with the simple tweaks he made to fix them and finally serves a Mirage hello world page.

More than just static sites

Static sites have become the new ‘hello world’ app. They’re simple to manage, low-risk and provide lots of opportunities to experience something new. These aspects make them ideal for discovering the benefits (and trade offs) of the unikernel approach and I look forward to seeing what variations people come up with — For instance, there aren’t any public instructions for deploying to Rackspace so it would be great to read about someone’s experiences there. However, there are also many other applications that also fit the above criteria of simplicity, low risk and plentiful learning opportunities.

Thomas Leonard decided to create a unikernel for a simple REST service for queuing package uploads for 0install. His post takes you from the very beginning, with a simple hello world program running on Xen, all the way through to creating his REST service. Along the way there a lots of code snippets and explanations of the libraries being used and what they’re doing. This is a great use-case for unikernels and there are a lot of interesting things to take from this post, for example the ease with which Thomas was able to find and fix bugs using regular tools. There’s also lots of information on performance testing and optimising of the unikernel, which he covers in a follow-up post, and he even built tools to visualise the traces.

Of course, there’s much more activity out there than described in this post as people continually propose ideas on the Mirage mailing list — both for things they would like to try out and issues they came up against. In my last post, I pointed out that the workflow is applicable to any type of unikernel and as Thomas showed, with bit of effort it’s already possible to create useful, real-world services using the many libraries that already exist. There’s also a lot of scaffolding in the mirage-skeleton repo that you can build on which makes it even easier to get involved. If you want to dive deeper into the libraries and perhaps learn OCaml, there are lots of resources online and projects to get involved with too.

Now is a great time to try building a unikernel for yourself and as you can see from the posts above, shared experiences help other people progress further and branch out into new areas. When you’ve had a chance to try something out please do share your experiences online!

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This post also appears on the Nymote blog.