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What are Clouds?

Like many in the community, I am often called upon to explain what OpenStack is to somebody completely unfamiliar with it. Usually this goes one of two ways: they turn out to be familiar enough with cloud computing to quickly grasp it by analogy, or their eyes glaze over at the mention of the words ‘cloud computing’ and no further explanation is sought or offered. When faced with someone who is persistently curious but not an industry insider, you immediately know you’re in trouble.

And so it came to pass that I found myself a couple of years ago wondering how exactly to explain to an economist why cloud computing is a big deal. I think I have actually figured out an answer: cloud computing can be seen as the latest development in a long trend of reducing the transaction costs that prevent us from allocating our resources efficiently.

(A live-action version of this post from the most recent OpenStack Summit in Barcelona is available on video.)

Cast your mind back to the days of physical hardware. When you wanted to develop and deploy a software service you first had to order servers, have them physically shipped to you, then installed and wired to the network. The process typically took weeks just from the vendor’s side, not to mention the time required to get your own ducks in a row first. As a result you had to buy more servers than you could fully utilise, and buy them earlier than you wanted them, because you could not rely on responding rapidly to changing demand.

Virtualisation revolutionised this cycle by cutting the slow purchasing, shipping and racking steps out of the loop. (These still had to happen, of course, but they no longer had to happen synchronously.) Instead, when you wanted a server you simply put in a request, somebody would create a virtual machine and allocate it to you. The whole process could easily be done in less than a day.

Yet as much as this was a huge leap forward, it was still slower than it needed to be, because there was still a human in the loop. The next step was to make the mechanism directly accessible to the developer—Infrastructure as a Service. That seemingly simple change has a number of immediate consequences, first amongst which is the need for robust multitenancy. This is the key difference between tools like OpenStack Nova and the preceding generation of virtualisation platforms, like oVirt. Transaction costs have dropped to near zero—where before allocating a new box took less than a day and you might do it every few weeks or so, now it takes seconds and you can easily do it 20 times a day without a second thought.

Before we congratulate ourselves too much though, remember that our goal was to remove humans from the loop… but we still have one: the developer (or sysadmin). Being able to adjust your resource utilisation 20 times a day is great, but mostly wasted if you can only do it during the 8 hours that somebody is parked in front of Horizon clicking buttons. For that reason, I don’t regard this use case as a ‘cloud’ at all, even though to hear some people talk you might think that this is the only thing that OpenStack is for. It could more accurately be described as a Virtual Private Server hosting service.

My working definition of a true ‘cloud’ service, then, is one where the application itself can control its own infrastructure. (Where ‘application’ includes not only software running on virtual compute infrastructure but also services built into the cloud itself that effectively form a part of it—a minimal description of such an application is likely a Heat template not a software package.) The developer might do the initial deployment, but from then on the application can manage itself autonomously.

You can actually go even further: if you use continuous deployment then you can eliminate the developer’s direct involvement altogether. There is now a Heat plugin for Jenkins to help you do this. Other options include the Ansible-based Zuul project, developed by the OpenStack Infra team, and the OpenStack Solum project.

Of course clouds of this type have been available for some years. However, the other thing we have learned since the 1990s is that writing your application to depend on a proprietary API now will often lead to wailing and gnashing of teeth later. As cloud services and APIs become part of the application, an Open Source cloud with a panoply of service provider options plus the ability to operate it yourself is your insurance against vendor lock-in. That’s why it is critical that OpenStack succeed, and succeed at delivering more than just Virtual Private Servers. Because there is no bigger transaction cost than having to rewrite your application to move to a better service provider.