Kubernetes is deprecating Docker?
Docker support is not going away, it is just deprecating the "Dockershim"
Kubernetes using CRI(Kubernetes created a standard interface called CRI for all runtime implementations.) for all runtime and here docker is most widely used. Moreover, docker is not only the container runtime , but also we can use contained, CRI-O, Rkt etc. So kubelet is not directly talking to Container runtime, instead, it is talking to container runtime through a Container Runtime Interface. In the case of docker Kubernetes cannot use CRI to communicate with docker runtime. Since docker is not implemented with any CRI. So Kubernetes developed a wrapper like application called "dockershim" for communicating with docker runtime, which speaks CRI protocol on one side and Dockerd protocol on the other.
When this will fully be removed.
As of now 12-17-2020 K8S V1.20 - Kubelet start showing a warning message1.21 - will also show the same warning message1.22 - will also show the same warning message1.23 - dockershim will remove
Questions:
Q1: Do we need to install docker?
Ans: No, you don't need to install docker , instead we need to install "containerd" or CRI-O
Q2: Your docker images will work?
Ans: Yes, you can push the image to your registry, "docker ps" can't see stuff created by CRI. Instead, there is a separate tool "crictl"
docker ps --> crictl ps, docker info --> crictl info etc
Q3: What about performance and security?
Ans: For docker runtime, K8S has lots of unwanted docker modules like API, CLI, and Server( in the server, we have container runtime, Volume, and network) but K8S only needs the runtime. So removing the docker runtime makes better performance and thus fewer components fewer security risks.
Q4: What is the name of container runtime for docker?
Ans: Containerd, which is already under the part of CNCF which is maintained and developed as a separate project. ContainerD is the second most alternative of using docker as a runtime.
Q5: Containerd is using any of the service providers?
Ans: Containerd is already used by major Cloud platforms ( AWS EKS, Google Kubernetes Service)
Q6: Do I need to make any modifications for my managed K8S cluster running on AWS,GCP?
Ans: Cloud providers will take care of installing the binaries and container runtime on K8S worker node.
Q7: On-prem K8S cluster?
Yes, Action required, there are two options: 1st. Change the container runtime as "containerd" or CRI-O , 2nd. We still want to use "dockershim" manually install it on your cluster, since Miratis now take control of dockershim https://www.mirantis.com/blog/mirantis-to-take-over-support-of-kubernetes-dockershim-2/
