Step 1: Before starting the cluster, first create a Vagrantfile file inside a folder of your choice. As prerequisites you need Virtualbox and Vagrant installed and configured. Follow the steps provided to create the Kubernetes cluster. The latter will continue to run our Docker containers and to pull images from the Docker registry as Docker produces OCI compliant images.īut let's come to us! In this article, we’ll walk you through creating a Kubernetes cluster with containerd rather than Docker. Cluster Set-up on Vagrant VMsīelow we've written a basic Vagrantfile and scripts configuration for anyone to understand. Docker has played, and will play, a fundamental role within the Kubernetes ecosystem. If you have a cluster already provisioned by major cloud providers like GKE, EKS, or AKS (which defaults to containerd) or if you are just a Kubernetes user, this has no impact on you. Should I stop using Kubernetes with Docker?
Taking up the architecture explained above, Docker isn't a container runtime and, as we have already said above, it is a series of tools to interact with containerd and only a middle-man.
Why doesn't Kubernetes need Docker as the container runtime?ĭocker is older than Kubernetes and didn't implement CRI, sowhy does it work? The Dockershim component has been created to allow you to interact with the CRI. But today, there are alternatives to Docker and it no longer makes sense for Kubernetes to maintain this additional level of complexity. Because it's standardized in a spec, you can choose which CRI implementation you want to use or write your own. To work, Kubernetes has needed a container runtime that is supported by CRI.ĬRI is a Kubernetes API that defines the way that Kubernetes interacts with different container runtimes. As a result, an image can run in any other system that respects this standard. The OCI added interoperability among different container runtime solutions. OCI maintains a reference implementation called runc, and containerd uses runc in the background to interact with containers.
A specification that describes how to interact and run a container.The requirements for the image in the binary format.They have introduced two specific standards: Docker Inc and CoreOS created the Open Container Initiative with the mission of producing standard formats. Kubernetes takes the idea of containers and instead of running containerized applications on one server, distributes them across a cluster.ĭue to the popularity of containers, there was a need for an open image standard. In order to understand why Kubernetes and Docker became famous together, let's understand how Docker is integrated within Kubernetes and what Open Container Initiative (OCI) and Container Runtime Interface (CRI) mean. Kubernetes? What does it have to do with all this? That was why Docker became so popularly known as a "container".
It was created in such a way that everyone can install it, build container images, pull them from registries, and create, start, and manage containers. Docker Architectureĭocker, defined as a "container", is nothing more than a user-friendly tool for interacting with containers. As the mission evolved, LXC was changed to containerd.Ī current Docker set-up is split into: containerd, for managing containers, and dockerd, a persistent process daemon that provides information from the Docker host machine. It is important to segregate methods because of running processes independently.ĭocker used Linux Containers (LXC) because of the runtime backend. Official Docker Documentation in Docker overviewĭocker makes use of the Linux kernel and functions of the kernel.
Docker enables you to separate your applications from your infrastructure so you can deliver software quickly. Mystery inside Dockerĭocker is an open platform for developing, shipping, and running applications. To date, for many there's just the only one word called "DOCKER" to refer to all this. It seems there's no difference between the company, the containers, the images and the tools that are used by developers.
In today's world, it's still difficult to understand what Docker is.
Then, why all this fuss? Should we continue writing Dockerfiles? In late 2020, the Kubernetes team deprecated Docker and announced that support will be completely removed at the end of 2021. This deprecation has brought multiple changes, creating a little confusion because of using Docker as the CRI instead of Docker as the OCI.