Intro

Installation example of Kubernetes Cluster on Debian 11 Hosts used in this sample:

c3-control-plane
c3-worker-01
c3-worker-02

Host specs:
VM's with 8CPUs, 16GB Ram each, running Debian12

Host file example of c2-control-plane

127.0.1.1       c2-control-plane
127.0.0.1       localhost

192.168.2.71    c3-control-plane
192.168.2.88    c3-worker-01
192.168.2.89    c3-worker-02

Installation on Master and on all Nodes

Hostnames

Hostnames used in this Lab, makle sure to add them into /etc/hosts on all machines

c3-control-plane
c3-worker-01
c3-worker-02

Load required modules and set kernel settings

cat << EOF |  tee /etc/modules-load.d/containerd.conf
overlay
br_netfilter
EOF

cat << EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

Turn off swap

sudo sed -i '/swap/d' /etc/fstab

Apply

modprobe overlay
modprobe br_netfilter
sysctl --system
swapoff -a

Install an NTP server otherwise etcd will be mad.

apt install -y chrony

Containerd

Requires the Docker repository

apt install -y curl gpg lsb-release apparmor apparmor-utils
curl -fsSL https://download.docker.com/linux/debian/gpg | gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null

Update and install

apt update
apt-get install -y containerd.io

Create a default configuration

mkdir -p /etc/containerd
containerd config default | tee /etc/containerd/config.toml

Open /etc/containerd/config.toml
- Search

[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]

Underneath add or change to:

 SystemdCgroup = true

Restart and check the service

systemctl restart containerd
systemctl status containerd

Kubernetes

Repository

apt-get install -y apt-transport-https ca-certificates curl
echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.31/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.31/deb/Release.key | gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
apt-get update

Additional Packages

Need iptables

apt-get install -y iptables libiptc0/stable libxtables12/stable

Need the containertools (https://github.com/flannel-io/flannel)

apt-get install containernetworking-plugins

Install and Hold

apt-get install -y kubelet kubeadm kubectl
apt-mark hold kubelet kubeadm kubectl

Initialization - MASTER ONLY

Init

ATTENTION As per Flannel requirement: You need to choose the below network

root@c3-control-plane:~# sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --kubernetes-version 1.31.1
[init] Using Kubernetes version: v1.31.1
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action beforehand using 'kubeadm config images pull'
W0924 20:27:37.309409    3434 checks.go:846] detected that the sandbox image "registry.k8s.io/pause:3.8" of the container runtime is inconsistent with that used by kubeadm.It is recommended to use "registry.k8s.io/pause:3.10" as the CRI  sandbox image.

[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [c3-control-plane kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.2.71]
[certs] Generating "apiserver-kubelet-client" certificate and key
[ certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [c3-control-plane localhost] and IPs [192.168.2.71 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [c3-control-plane localhost] and IPs [192.168.2.71 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "super-admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests"
[kubelet-check] Waiting for a healthy kubelet at http://127.0.0.1:10248/healthz. This can take up to 4m0s
[kubelet-check] The kubelet is healthy after 1.002763895s
[api-check] Waiting for a healthy API server. This can take up to 4m0s
[api-check] The API server is healthy after 7.551840294s
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node c3-control-plane as control-plane by adding the labels: [node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node c3-control-plane as control-plane by adding the taints [node-role.kubernetes.io/control-plane:NoSchedule]
[bootstrap-token] Using token: lh8xc6.3sko0430n0rz8awq
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

 mkdir -p $HOME/.kube
 sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
 sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

 export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.2.71:6443 --token lh8xc6.3sko0430n0rz8awq \
       --discovery-token-ca-cert-hash sha256:cfc8aa385d1898a567a0370a3b9ed9331aae78e13c9414917fe5f5acb62851df

Regular user setup

Switch to a normal, non root user

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Before Flannel

vmadmin@c3-control-plane:~$ kubectl get nodes
NAME                  STATUS     ROLES           AGE     VERSION
c3-control-plane      NotReady   control-plane   35m   v1.31.1

Apply Flannel

vmadmin@c3-control-plane:~$ kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml
namespace/kube-flannel created
serviceaccount/flannel created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
configmap/kube-flannel-cfg created
daemonset.apps/kube-flannel-ds created

After Flannel

After Flannel - This may take a while

vmadmin@c3-control-plane:~$ kubectl get nodes
NAME               STATUS   ROLES           AGE   VERSION
c3-control-plane   Ready    control-plane   35m   v1.31.1

Join the worker nodes

Node01

root@c3-worker-01:~# kubeadm join 192.168.2.71:6443 --token lh8xc6.3sko0430n0rz8awq \
        --discovery-token-ca-cert-hash sha256:cfc8aa385d1898a567a0370a3b9ed9331aae78e13c9414917fe5f5acb62851df
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-check] Waiting for a healthy kubelet at http://127.0.0.1:10248/healthz. This can take up to 4m0s
[kubelet-check] The kubelet is healthy after 1.002183203s
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

Node02

root@c3-worker-02:~# kubeadm join 192.168.2.71:6443 --token lh8xc6.3sko0430n0rz8awq \
        --discovery-token-ca-cert-hash sha256:cfc8aa385d1898a567a0370a3b9ed9331aae78e13c9414917fe5f5acb62851df
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-check] Waiting for a healthy kubelet at http://127.0.0.1:10248/healthz. This can take up to 4m0s
[kubelet-check] The kubelet is healthy after 1.00237113s
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

Show Results

# kubectl get nodes
vmadmin@c3-control-plane:~$ kubectl get nodes
NAME               STATUS   ROLES           AGE     VERSION
c3-control-plane   Ready    control-plane   32m     v1.31.1
c3-worker-01       Ready    <none>          4m54s   v1.31.1
c3-worker-02       Ready    <none>          112s    v1.31.1

Optional Labeling

vmadmin@c3-control-plane:~$ kubectl label node c3-worker-01 node-role.kubernetes.io/worker=worker
node/c3-worker-01 labeled
vmadmin@c3-control-plane:~$ kubectl label node c3-worker-02 node-role.kubernetes.io/worker=worker
node/c3-worker-02 labeled
vmadmin@c3-control-plane:~$ kubectl get nodes
NAME               STATUS   ROLES           AGE     VERSION
c3-control-plane   Ready    control-plane   19m     v1.31.1
c3-worker-01       Ready    worker          8m18s   v1.31.1
c3-worker-02       Ready    worker          94s     v1.31.1