Kubernetes' Growth, Future, and Application-Level Innovation

And so although you’re only a year old, you really have an [old soul](http://queue.acm.org/detail.cfm?id=2898444). I’m just one of the [many people raising you](https://kubernetes.io/blog/2016/07/happy-k8sbday-1), but it’s a wonderful learning experience for me to be able to work with the people that have built these incredible systems and have all this domain knowledge. Yet because we started from scratch (rather than taking the existing Borg code) we’re at the same level and can still have genuine discussions about how to raise you. Well, at least as close to the same level as we could ever be, but it’s to their credit that they are all far too nice ever to mention it! If I would pick just two of the wise decisions those brilliant people made: - Labels & selectors give us declarative “pointers”, so we can say “why” we want things, rather than listing the things directly. It’s the secret to how you can scale to [great heights](https://kubernetes.io/blog/2016/07/thousand-instances-of-cassandra-using-kubernetes-pet-set); not by naming each step, but saying “a thousand more steps just like that first one”. - Controllers are state-synchronizers: we specify the goals, and your controllers will indefatigably work to bring the system to that state. They work through that strongly-typed API foundation, and are used throughout the code, so Kubernetes is more of a set of a hundred small programs than one big one. It’s not enough to scale to thousands of nodes technically; the project also has to scale to thousands of developers and features; and controllers help us get there. And so on we will go! We’ll be replacing those controllers and building on more, and the API-foundation lets us build anything we can express in that way - with most things just a label or annotation away! But your thoughts will not be defined by language: with third party resources you can express anything you choose. Now we can build Kubernetes without building in Kubernetes, creating things that feel as much a part of Kubernetes as anything else. Many of the recent additions, like ingress, DNS integration, autoscaling and network policies were done or could be done in this way. Eventually it will be hard to imagine you before these things, but tomorrow’s standard functionality can start today, with no obstacles or gatekeeper, maybe even for an audience of one. So I’m looking forward to seeing more and more growth happen further and further from the core of Kubernetes. We had to work our way through those phases; starting with things that needed to happen in the kernel of Kubernetes - like replacing replication controllers with deployments. Now we’re starting to build things that don’t require core changes. But we’re still still talking about infrastructure separately from applications. It’s what comes next that gets really interesting: when we start building applications that rely on the Kubernetes APIs. We’ve always had the Cassandra example that uses the Kubernetes API to self-assemble, but we haven’t really even started to explore this more widely yet. In the same way that the S3 APIs changed how we build things that remember, I think the k8s APIs are going to change how we build things that think. So I’m looking forward to your second birthday: I can try to predict what you’ll look like then, but I know you’ll surpass even the most audacious things I can imagine. Oh, the places you’ll go!

The author discusses Kubernetes' design choices like Labels & Selectors and Controllers, and how they contribute to its scalability. The focus shifts to the future, highlighting the potential for external growth through third-party resources, allowing for the creation of new functionalities without core changes. The author envisions a future where applications rely on Kubernetes APIs to self-assemble, similar to how S3 APIs changed data storage. They anticipate significant innovation at the application level, expecting Kubernetes to evolve beyond current predictions.