Before we start with CRI-O, we need talk about the basics. The best place to start will be container runtimes. We already know what containers, Docker, and Kubernetes are. But how does this all work on a low level? The following diagram illustrates a high-level overview of the communications between Kubernetes and containers:
Kubernetes-to-container communications
As you can see, it is not just Kubernetes talking to the container directly. There are two additional layers in the diagram. Let's discuss why we actually need them:
- Container Runtime: Each and every container technology, such as Docker, Rkt, or Windows Containers, has its own runtime. In short, Container Runtime is a set of scripts and software tools to run and maintain the work of a container.
- Container Runtime Interface (CRI): As the name implies, CRI is an...