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Running CRI-O with kubeadm

This tutorial assumes you've already installed and setup CRI-O. If you have not, start here. It also assumes you've set up your system to use kubeadm. If you haven't done so, here is a good tutorial

Configuring CNI

kubeadm expects a POD Network CIDR (--pod-network-cidr) to be defined when you install the cluster. The value of --pod-network-cidr depends on which CNI plugin you choose.

CNI Plugin CIDR Notes
Bridge plugin (default) 10.85.0.0/16 The default bridge plugin is defined here. This is only suitable when your cluster has a single node.
Flannel 10.244.0.0/16 This is a good choice for clusters with multiple nodes.

For example, to use the script below with the bridge plugin, run export CIDR=10.85.0.0/16.

A list of CNI plugins can be found in the Cluster Networking Kubernetes documentation. Each plugin will define its own default CIDR.

Running kubeadm

Given you've set CIDR, and assuming you've set the cgroup_driver in your CRI-O configuration as systemd (which is the default value), all you need to do is start crio (as defined here), and run: kubeadm init --pod-network-cidr=$CIDR --cri-socket=unix:///var/run/crio/crio.sock

Running kubeadm in an off line network

We will assume that the user has installed CRI-O and all necessary packages. We will also assume that all necessary components are configured and everything is working as expected. The user should have a private repo where the container images are pushed. An example of container images for Kubernetes version 1.18.2:

$ kubeadm config images list --image-repository user.private.repo --kubernetes-version=v1.18.2
user.private.repo/kube-apiserver:v1.18.2
user.private.repo/kube-controller-manager:v1.18.2
user.private.repo/kube-scheduler:v1.18.2
user.private.repo/kube-proxy:v1.18.2
user.private.repo/pause:3.2
user.private.repo/etcd:3.4.3-0
user.private.repo/coredns:1.6.7

The user needs to configure the registries.conf file.

Sample of configurations:

$ cat /etc/containers/registries.conf
unqualified-search-registries = ["user.private.repo"]

[[registry]]
prefix = "registry.k8s.io"
insecure = false
blocked = false
location = "registry.k8s.io"

[[registry.mirror]]
location = "user.private.repo"

Next the user should reload and restart the CRI-O service to load the configurations.