Install Kubernetes 1.26 on Debian 11 with Flannel

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Revision as of 17:34, 9 March 2023 by Admin (talk | contribs) (→‎Intro)
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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

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

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 

# 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/
https://www.linuxtechi.com/install-kubernetes-cluster-on-debian/
https://www.oueta.com/linux/create-a-debian-11-kubernetes-cluster-with-kubeadm/

  • About calico

https://www.inovex.de/de/blog/kubernetes-networking-2-calico-cilium-weavenet/#

  • Interesting about installation via Ansible:

https://www.linuxsysadmins.com/install-kubernetes-cluster-with-ansible/

  • About Container Network Interface (CNI) - Add Ons

https://kubernetes.io/docs/concepts/cluster-administration/addons/
https://platform9.com/blog/the-ultimate-guide-to-using-calico-flannel-weave-and-cilium/
https://kubevious.io/blog/post/comparing-kubernetes-container-network-interface-cni-providers
https://www.linux-magazin.de/ausgaben/2017/08/netz-in-kubernetes/
https://ronaknathani.com/blog/2020/08/how-a-kubernetes-pod-gets-an-ip-address/

  • 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/
https://www.programmersought.com/article/7824768991/

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