Jovan StosicThe Symbiosis Between Kubernetes and Docker
The question, “Kubernetes or Docker?” in itself is rather absurd, like comparing apples to oranges. One isn’t an alternative to the other. Quite the contrary; Kubernetes can run without Docker and Docker can function without Kubernetes. But Kubernetes can (and does) benefit greatly from Docker and vice versa.
Docker is a standalone software that can be installed on any computer to run containerized applications. Containerization is an approach of running applications on an OS such that the application is isolated from the rest of the system. You create an illusion for your application that it is getting its very own OS instance, although there may be other containers running on same system. Docker is what enables us to run, create and manage containers on a single operating system.
Kubernetes turns it up to 11, so to speak. If you have Docker installed on a bunch of hosts (different operating systems), you can leverage Kubernetes. These nodes, or Docker hosts, can be bare-metal servers or virtual machines. Kubernetes can then allow you to automate container provisioning, networking, load-balancing, security and scaling across all these nodes from a single command line or dashboard. A collection of nodes that is managed by a single Kubernetes instance is referred to as a Kubernetes cluster.
Now, why would you need to have multiple nodes in the first place? The two main motivations behind it are:
- To make the infrastructure more robust: Your application will be online, even if some of the nodes go offline, i.e, High availability.
- To make your application more scalable: If workload increases, simply spawn more containers and/or add more nodes to your Kubernetes cluster.
Kubernetes automates the process of scaling, managing, updating and removing containers. In other words, it is a container orchestration platform. While Docker is at the heart of the containerization, it enables us to have containers in the first place.