Overview
This blog article will help you install a single master Kubernetes 1.16 cluster using kubeadm on Debian 9+, Ubuntu 18.04+. This guide will deploy three(3) servers, one master node and two worker nodes, however you can deploy as many servers to accomplish your goal. This guide uses Containerd 1.3.0 as CRI, Flannel as CNI plugin
Prerequisites
I will cover steps for operating systems as mentioned below. Minimum server requirements:
- Debian 9+, Ubuntu 18.04+ tested
- 2 GB or more of RAM per node (Any less will leave little room for your Apps)
- 2 CPUs or more on the Master node
- Full network connectivity between all nodes in the cluster (public or private network is fine)
- Root access maybe required
Setup Environment
| Hostname | Role | IP Address |
| k8s-master-01 | master / control plane | 192.168.0.10 |
| k8s-worker-01 | worker node | 192.168.0.20 |
| k8s-worker-02 | worker node | 192.168.0.30 |
Disable Swap
Swap needs to be disabled. Kubeadm will check to make sure that swap is disabled. Turn swap off and disable for future reboots.
sudo swapoff -a
sudo sed -i.bak '/swap/d' /etc/fstabDisable Firewall
Stop and disable the firewall to avoid any issues. Kubernetes uses IPTables to handle inbound and outbound traffic.
sudo systemctl status firewalld
sudo systemctl stop firewalld
sudo systemctl disable firewalldDisable SELinux
We need to disable SELinux or set it to permissive mode if it’s enabled. I’m setting to Permissive mode.
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/configConfigure IPTables to receive bridged network traffic
Enable IPTables to route bridged network traffic correctly
sudo bash -c 'cat <<EOF > /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF'Load system configuration files
Apply configuration changes made above
sudo sysctl --systemInstall Containerd with Release Tarball
Containerd Prerequisites
sudo bash -c 'cat <<EOF > /etc/modules-load.d/containerd.conf
overlay
br_netfilter
EOF'
sudo modprobe overlay
sudo modprobe br_netfilterInstall Updates and Containerd 1.3.0
Update the system and install libseccomp2 module, required by containerd
sudo apt-get update
sudo apt-get install libseccomp2
wget https://storage.googleapis.com/cri-containerd-release/cri-containerd-1.3.0.linux-amd64.tar.gz
sudo tar --no-overwrite-dir -C / -xzf cri-containerd-1.3.0.linux-amd64.tar.gz
sudo systemctl enable containerd && systemctl start containerdGenerate containerd configuration
sudo mkdir -p /etc/containerd
# Run command as root [sudo su -]
containerd config default > /etc/containerd/config.toml
# Exit rootReload and restart containerd
sudo systemctl daemon-reload
sudo systemctl restart containerdInstall Kubeadm, Kubelet and Kubectl
sudo apt-get update && apt-get install -y apt-transport-https ca-certificates curl software-properties-common
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
sudo cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectlEnable and Start Kubelet
sudo systemctl enable kubelet
sudo systemctl start kubeletConfigure cgroup driver used by kubelet on control-plane node
sudo vim /etc/systemd/system/kubelet.service.d/0-containerd.conf
[Service]
Environment="KUBELET_EXTRA_ARGS=--container-runtime=remote --runtime-request-timeout=15m --container-runtime-endpoint=unix:///run/containerd/containerd.sock"Restart the kubelet to pick up the configuration
sudo systemctl daemon-reload
sudo systemctl restart kubeletInitialize kubeadm on master
Note: This step only for the master node
kubeadm init --pod-network-cidr 10.244.0.0/16 --apiserver-advertise-address 172.16.0.4
# To start using your cluster, Login as a regular user:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
# Alternatively, if you are the root user, you can run:
export KUBECONFIG=/etc/kubernetes/admin.confJoin Worker Nodes to Cluster
Note: Perform this as root on all worker nodes you want to join cluster
# Run the command that was output by kubeadm init
kubeadm join --token <token> <control-plane-host>:<control-plane-port> --discovery-token-ca-cert-hash sha256:<hash>
# If you do not have the token, you can get it by running the following command on the control-plane node
kubeadm token list
# Tokens expire after 24 hours. Joining a node after the current token has expired? You can create a new token:
kubeadm token create
Deploy Pod network – Flannel
For flannel to work correctly, --pod-network-cidr=10.244.0.0/16 has to be passed to kubeadm init. See Kubernetes docs for other CNI configurations.
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/2140ac876ef134e0ed5af15c65e414cf26827915/Documentation/kube-flannel.ymlTest the Cluster
Do a series of tests for your cluster
larry@master-01:~$ kubectl get pods --namespace kube-system --output wide
NAME READY STATUS RESTARTS AGE IP NODE
coredns-5644d7b6d9-85trw 1/1 Running 0 48m 10.244.1.2 worker-01
coredns-5644d7b6d9-lgzwb 1/1 Running 0 48m 10.244.2.2 worker-02
etcd-master-01 1/1 Running 0 47m 10.240.0.3 master-01
kube-apiserver-master-01 1/1 Running 0 47m 10.240.0.3 master-01
kube-controller-manager-master-01 1/1 Running 0 47m 10.240.0.3 master-01
kube-flannel-ds-amd64-58h27 1/1 Running 0 43m 10.240.0.5 worker-02
kube-flannel-ds-amd64-94hgj 1/1 Running 0 43m 10.240.0.3 master-01
kube-flannel-ds-amd64-h6rl4 1/1 Running 0 43m 10.240.0.4 worker-01
kube-proxy-9flw7 1/1 Running 0 45m 10.240.0.4 worker-01
kube-proxy-hbj2g 1/1 Running 0 48m 10.240.0.3 master-01
kube-proxy-n49zq 1/1 Running 0 45m 10.240.0.5 worker-02
kube-scheduler-master-01 1/1 Running 0 47m 10.240.0.3 master-01 larry@master-01:~$ kubectl cluster-info
Kubernetes master is running at https://10.240.0.3:6443
KubeDNS is running at https://10.240.0.3:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.Verify the services
larry@master-01:~$ kubectl get services -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 41m
larry@master-01:~$
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