View source for Install Kubernetes 1.26 on Debian 11 with Flannel

=Intro=
Installation example of Kubernetes Cluster on Debian 11
Hosts used in this sample:
*c1-control-plane
*c1-worker-1
*c1-worker-2

*Host specs:
*VM's with 2CPUs, 4GB Ram each, running Debian11

*'''Note''' No sudo was used in this Lab, instead work as root

*Host file example of c1-control-plane
 127.0.1.1       c1-control-plane
 127.0.0.1       localhost
 192.168.178.100 c1-control-plane vm-c1-control-plane
 192.168.178.101 c1-worker-1 vm-c1-worker-1
 192.168.178.102 c1-worker-2 vm-c1-worker-2

=Installation on Master and on all Nodes=
==Hostnames==
Hostnames used in this Lab, makle sure to add them into /etc/hosts on all machines
*c1-control-plane
*c1-worker-1
*c1-worker-2

==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
 curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg
 echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | tee /etc/apt/sources.list.d/kubernetes.list 
===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=1.26.0-00 kubeadm=1.26.0-00 kubectl=1.26.0-00
 apt-mark hold kubelet kubeadm kubectl

=Initialization - MASTER ONLY=
==Init==
'''ATTENTION''' As per Flannel requirement: You need to choose the below network
*https://gist.github.com/rkaramandi/44c7cea91501e735ea99e356e9ae7883
*https://stackoverflow.com/questions/48984659/understanding-kubeadm-init-command-for-flannel

 # '''sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --kubernetes-version 1.26.0'''

 root@vm-c1-control-plane:~# kubeadm init --pod-network-cidr=10.244.0.0/16 --kubernetes-version 1.26.0
 [init] Using Kubernetes version: v1.26.0
 [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 in beforehand using 'kubeadm config images pull'
 [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 [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local vm-c1-control-plane] and IPs [10.96.0.1 192.168.178.100]
 [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 [localhost vm-c1-control-plane] and IPs [192.168.178.100 127.0.0.1 ::1]
 [certs] Generating "etcd/peer" certificate and key
 [certs] etcd/peer serving cert is signed for DNS names [localhost vm-c1-control-plane] and IPs [192.168.178.100 127.0.0.1 ::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 "kubelet.conf" kubeconfig file
 [kubeconfig] Writing "controller-manager.conf" kubeconfig file
 [kubeconfig] Writing "scheduler.conf" kubeconfig file
 [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
 [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"
 [etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
 [wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
 [apiclient] All control plane components are healthy after 7.503176 seconds
 [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 vm-c1-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 vm-c1-control-plane as control-plane by adding the taints [node-role.kubernetes.io/control-plane:NoSchedule]
 [bootstrap-token] Using token: cmp2ge.my1xmrxxonnp47vi
 [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 192.168.178.100:6443 --token cmp2ge.my1xmrxxonnp47vi \
        --discovery-token-ca-cert-hash sha256:0510de44004a0bcfceff8221c122b5116ce6fd8f507622a498abec3985a42fc1

==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==
Before Flannel
 vmadmin@vm-c1-control-plane:~$ '''kubectl get nodes'''
 NAME                  STATUS     ROLES           AGE     VERSION
 vm-c1-control-plane   '''NotReady'''   control-plane   2m30s   v1.24.0

==Apply Flannel==

 # '''kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml'''

 vmadmin@vm-c1-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@vm-c1-control-plane:~$ kubectl get nodes
 NAME                  STATUS   ROLES           AGE     VERSION
 vm-c1-control-plane   '''Ready'''    control-plane   3m35s   v1.24.0

=Join the worker nodes=
==Node01==
 # '''kubeadm join 192.168.178.100:6443 --token cmp2ge.my1xmrxxonnp47vi --discovery-token-ca-cert-hash sha256:0510de44004a0bcfceff8221c122b5116ce6fd8f507622a498abec3985a42fc1'''

 root@vm-c1-worker-1:~# kubeadm join 192.168.178.100:6443 --token cmp2ge.my1xmrxxonnp47vi \
        --discovery-token-ca-cert-hash sha256:0510de44004a0bcfceff8221c122b5116ce6fd8f507622a498abec3985a42fc1
 [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-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==
 # '''kubeadm join 192.168.178.100:6443 --token cmp2ge.my1xmrxxonnp47vi --discovery-token-ca-cert-hash sha256:0510de44004a0bcfceff8221c122b5116ce6fd8f507622a498abec3985a42fc1'''

 root@vm-c1-worker-2:~# kubeadm join 192.168.178.100:6443 --token cmp2ge.my1xmrxxonnp47vi \
        --discovery-token-ca-cert-hash sha256:0510de44004a0bcfceff8221c122b5116ce6fd8f507622a498abec3985a42fc1
 [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-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@vm-c1-control-plane:~$ kubectl get nodes
 NAME                  STATUS   ROLES           AGE     VERSION
 vm-c1-control-plane   Ready    control-plane   7m37s   v1.24.0
 vm-c1-worker-1        Ready    <none>          64s     v1.24.0
 vm-c1-worker-2        Ready    <none>          58s     v1.24.0

==Optional Labeling==
 kubectl label node vm-c1-worker-1 node-role.kubernetes.io/worker=worker
 kubectl label node vm-c1-worker-2 node-role.kubernetes.io/worker=worker

 vmadmin@vm-c1-control-plane:~$ kubectl get nodes
 NAME                  STATUS   ROLES           AGE     VERSION
 vm-c1-control-plane   Ready    control-plane   4m51s   v1.26.0
 vm-c1-worker-1        Ready    worker          2m56s   v1.26.0
 vm-c1-worker-2        Ready    worker          2m5s    v1.26.0

=Testing=
==Apply Test Pods==
*create nginx.yml
 ---
 apiVersion: v1
 kind: Pod
 metadata:
   name: nginx1
   labels:
     app: web
 spec:
   containers:
     - name: nginx1
       image: nginx
       ports:
         - containerPort: 80
 ---
 apiVersion: v1
 kind: Pod
 metadata:
   name: nginx2
   labels:
     app: web
 spec:
   containers:
     - name: nginx2
       image: nginx
       ports:
         - containerPort: 80

*Apply
 # kubectl create -f nginx.yml

*The result should look like:
 vmadmin@vm-c1-control-plane:~$ kubectl get pods -o wide
 NAME     READY   STATUS    RESTARTS   AGE   IP           NODE             NOMINATED NODE   READINESS GATES
 nginx1   1/1     Running   0          31s   10.244.2.4   vm-c1-worker-2   <none>           <none>
 nginx2   1/1     Running   0          31s   10.244.1.3   vm-c1-worker-1   <none>           <none>

==Network Test==
*Connect to nginx1:
 kubectl exec --stdin --tty nginx -- /bin/bash

*Install apps
 root@nginx1:/# apt-get update
 root@nginx1:/# apt-get install iputils-ping

*Ping Nginx2 (YES!!!)
 root@nginx1:/# ping 10.244.1.3
 PING 10.244.1.3 (10.244.1.3) 56(84) bytes of data.
 64 bytes from 10.244.1.3: icmp_seq=1 ttl=62 time=0.563 ms


=References=
*Self installation using calico
https://www.howtoforge.de/anleitung/kubernetes-cluster-mit-kubeadm-auf-debian-11-einrichten/ <br>
https://www.linuxtechi.com/install-kubernetes-cluster-on-debian/ <br>
https://www.oueta.com/linux/create-a-debian-11-kubernetes-cluster-with-kubeadm/ <br>
*About calico
https://www.inovex.de/de/blog/kubernetes-networking-2-calico-cilium-weavenet/# <br>
*Interesting about installation via Ansible: 
https://www.linuxsysadmins.com/install-kubernetes-cluster-with-ansible/ <br>
*About Container Network Interface (CNI) - Add Ons
https://kubernetes.io/docs/concepts/cluster-administration/addons/ <br>
https://platform9.com/blog/the-ultimate-guide-to-using-calico-flannel-weave-and-cilium/ <br>
https://kubevious.io/blog/post/comparing-kubernetes-container-network-interface-cni-providers <br>
https://www.linux-magazin.de/ausgaben/2017/08/netz-in-kubernetes/ <br>
https://ronaknathani.com/blog/2020/08/how-a-kubernetes-pod-gets-an-ip-address/ <br>
*Troubleshoot Flannel
https://www.continualintegration.com/miscellaneous-articles/how-do-you-solve-the-kubernetes-error-networkplugin-cni-failed-to-set-up-pod-network-open-run-flannel-subnet-env-no-such-file-or-directory/ <br>
https://www.programmersought.com/article/7824768991/ <br>