cri-dockerd VS containerd

$ wget https://github.com/Mirantis/cri-dockerd/releases/download/v0.3.9/cri-dockerd-0.3.9.amd64.tgz $ tar zxvf cri-dockerd-0.3.9.amd64.tgz $ cd cri-dockerd $ sudo mkdir -p /usr/local/bin $ sudo install -o root -g root -m 0755 cri-dockerd/usr/local/bin/cri-dockerd $ mkdir foo; cd foo $ git clone [email protected]:Mirantis/cri-dockerd.git $ cd cri-dockerd $ sudo install packaging/systemd/* /etc/systemd/system $ sudo sed -i -e 's,/usr/bin/cri-dockerd,/usr/local/bin/cri-dockerd,' /etc/systemd/system/cri-docker.service $ sudo systemctl daemon-reload $ sudo systemctl enable --now cri-docker.socket

I installed cri-dockerd using this documentation https://github.com/Mirantis/cri-dockerd

99% of what you just said is completely incorrect. containerd is not a facade for Docker, in fact the Docker engine is a facade for containerd. The OCI spec is also not a facade for Docker, Docker is simply one application which can create OCI compliant images which can be executed by runtimes like runc. Kubernetes has zero facades for Docker, unless you count the optional open-source cri-dockerd.

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/ Adjust netplan for static IP Adding br_netfilter and overlay to kernel Creating /etc/modules-load.d/k8s.conf with bridging and forwarding https://kubernetes.io/docs/setup/production-environment/container-runtimes/#forwarding-ipv4-and-letting-iptables-see-bridged-traffic Installing docker components https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker Installing cri-dockerd https://github.com/Mirantis/cri-dockerd Disabling swap https://graspingtech.com/disable-swap-ubuntu/ install kubeadm kubectl kubelet https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

Im trying to learn how to set up kubernetes cluster with kubeadm. Im using official kubernetes documentation ( maybe there is a better source?). My goal is to set it up with cri-dockerd and systemd. And to be honest its quite hard task to do it. Informations are scattered arround with links and sometimes its hard to know the order which steps should be executed. I have 2 Virtualbox machines, connected together with NAT network. A master and worker node. I performed these steps on both of them: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/ Adjust netplan for static IP Adding br_netfilter and overlay to kernel Creating /etc/modules-load.d/k8s.conf with bridging and forwarding https://kubernetes.io/docs/setup/production-environment/container-runtimes/#forwarding-ipv4-and-letting-iptables-see-bridged-traffic Installing docker components https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker Installing cri-dockerd https://github.com/Mirantis/cri-dockerd Disabling swap install kubeadm kubectl kubelet https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/ configure kubelet cgroup driver https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/configure-cgroup-driver/ So currently im at the configuring cgroup driver. I tried to execute kubeadm init kubeadm-config.yaml but kubeadm found 2 CRI endpoints. So i tried to point the correct one with this command kubeadm join --cri-socket /var/run/cri-dockerd.sock but i got discover:Invalid value: ::: bootstrapToken or file must be set And now im completely lost. And also im confused is this a moment for installing CNI (probably i will try with Calico) for pod communication or should i start the cluster first?

But not to worry, you can still use Docker as a container runtime in Kubernetes using the cri-dockerd adapter. cri-dockerd provides a shim for Docker Engine that lets you control Docker via the Kubernetes CRI. ****

As of version 1.24, either one of the other supported runtimes (e.g. containerd or CRI-O) or, in case you still want to rely on Docker Engine, cri-dockerd must be used. Further information on precautions that may be necessary due to the removal of Dockershim is provided by Kubernetes in a guide.

Kubernetes requires a tool which implements the Container Runtime Interface, a standardized API for starting & managing containers. This is from 2015-2016[1].

For a while Kubernetes has included something called the "dockershim", it's own implementation of a CRI interface that, under the hood, calls Docker or Podman. There's also tools like kind[2] ("kubernetes in docker") that go further- not just hosting Kubernetes worker containers in Docker, but hosting the main kubernetes daemons also in Docker.

Kubernetes deprecated Dockershim, formally in December 2020, but is just throwing the switch now in the upcoming 1.24, expected mid-April[3]. A company Mirantis has pledged to take over support of Dockershim[4], and is calling the new effort "cri-dockerd"[5]. This should allow Kubernetes workers to continue to run via Docker or Podman.

Kind is unaffected, since it runs the main Kubernetes controllers in Docker, which then launch their own opencontainerd (one off the main CRI implementations) inside that Docker container, nested like, so no dockership/cri-dockerd is needed).

[1] https://kubernetes.io/blog/2016/12/container-runtime-interfa...

[2] https://kind.sigs.k8s.io/

[3] https://kubernetes.io/blog/2022/01/07/kubernetes-is-moving-o...

[4] https://www.mirantis.com/blog/mirantis-to-take-over-support-...

[5] https://github.com/Mirantis/cri-dockerd

Containerd and nerdctl

Kubernetes on the backend used to utilize docker for much of its container runtime solutions. One of the modular features of Kubernetes is the ability to utilize a Container Runtime Interface or CRI. The problem was that Docker didn't really meet the spec properly and they had to maintain a shim to translate properly. Instead users could utilize the popular containerd or cri-o runtimes. These follow the Open Container Initiative or OCI's guidelines on container formats.

Container Engine: A runtime that executes and manages containers. Docker and containerd are popular container engines.

Multiple container runtimes are supported, like conatinerd, cri-o, or other CRI compliant runtimes.

This is a failed attempt to upstream part of containerd changes: https://github.com/containerd/containerd/pull/8789

Other part of containerd changes waits for gods-know-what: https://github.com/containerd/containerd/pull/9054

But I haven't gave up yet.

containerd is required by kubernetes to handle containers on its behalf. A big thanks to the HostAfrica blog for the information on setting containerd up for debain. So the containerd install will need to happen on both the WSL2 instance and the Raspberry Pis. For WSL2 you can just install containerd directly:

The context deadline exceeded: unknown is also in containerd, and is a known problem.

Get:1 https://download.docker.com/linux/ubuntu focal/stable amd64 containerd.io amd64 1.6.21-1 [28.3 MB]

Docker Desktop adds a bunch of stuff to simplify local development and that’s why it has a larger memory footprint. You don’t use that when deploying but something like https://containerd.io/.