What versions to use?

General Discussions
1

Hi
I’m trying to get kubernetes installed on CentOS 8, but there seems to be a version mismatch with docker-ce, selinux and containerd.io could i get a functioning combination of version numbers?
i followed How to Install a Kubernetes Cluster on CentOS 8 click by click.
Thanks in advance

2

I didn’t really put much effort into this, but just doing this seems to work for me.

Edited: Containerd needs to be reloaded after Docker is configured.

I needed dnf-utils and tc for this setup.

# dnf install -y dnf-utils tc

Some stuff related to bridged networks and iptables.

# cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
EOF

# cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

# sysctl --system

Add docker repo, install docker and containerd.

# yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
# dnf install -y docker-ce docker-ce-cli containerd.io

Configure docker for the cgroup driver.

cat <<EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

Enable and start containerd and docker.

# systemctl enable containerd
# systemctl restart containerd

# systemctl enable docker
# systemctl daemon-reload
# systemctl restart docker

Add the Kubernetes repo.

# cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
exclude=kubelet kubeadm kubectl
EOF

Disabling selinux is lazy, but it will make just getting things up easier.

# setenforce 0
# sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Install kube tools.

# dnf install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
# systemctl enable --now kubelet

Initialize the cluster.

# kubeadm init --pod-network-cidr=192.168.0.0/16

Export the admin’s kubeconfig so we can use kubectl.

# export KUBECONFIG=/etc/kubernetes/admin.conf

You will see that coredns is not ready yet.

# kubectl get pods -A

Add a CNI then wait for things to come up.

# kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
# kubectl get pods -A --watch

Things are now runnings. There is 1 coredns replica that isn’t up. That is because I just didn’t have the sufficient CPU resources available.

# kubectl get pods -A
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE
kube-system   calico-kube-controllers-58497c65d5-hjpk6   1/1     Running   0          10m
kube-system   calico-node-dxq7h                          1/1     Running   0          10m
kube-system   coredns-65595d68cf-vgv5m                   1/1     Running   0          36s
kube-system   coredns-65595d68cf-z6s5x                   1/1     Running   0          36s
kube-system   etcd-c01                                   1/1     Running   0          12m
kube-system   kube-apiserver-c01                         1/1     Running   0          12m
kube-system   kube-controller-manager-c01                1/1     Running   0          12m
kube-system   kube-proxy-r9r5w                           1/1     Running   0          12m
kube-system   kube-scheduler-c01                         1/1     Running   0          12m

I had to remove the taint because the node is a master.

# kubectl get nodes
NAME   STATUS   ROLES                  AGE   VERSION
c01    Ready    control-plane,master   14m   v1.22.1

# kubectl taint nodes c01 node-role.kubernetes.io/master-

After this I can now run nginx.

# kubectl run nginx-test --image nginx
pod/nginx-test created

# kubectl get pods
NAME         READY   STATUS    RESTARTS   AGE
nginx-test   1/1     Running   0          116s