Setup K8s cluster via kubeadm

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Kubernetes is an open source software tool for managing containerised workloads. It enables development teams to automate the deployment, scaling and management of applications. The kubeadm tool helps bootstrap a minimum viable Kubernetes cluster that conforms to best practices. This guide will walk you through how to install Kubernetes on Ubuntu 16.04.



Prerequisites

  • 3 Linux servers running Ubuntu 16.04
  • Access to a user account on each system with sudo or root privileges
  • The apt package manager, included by default
  • Command-line/terminal window (Ctrl-Alt-T)


Steps to Install Kubernetes on Ubuntu

Setup repository

Get the Docker gpg key:

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

Add the Docker repository:

$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
 $(lsb_release -cs) \
 stable"

Get the Kubernetes gpg key:

$ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

Add the Kubernetes repository:

$ cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

Update your packages:

$ sudo apt-get update

Install Docker, kubelet, kubeadm, and kubectl:

$ sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu kubelet=1.15.7-00 kubeadm=1.15.7-00 kubectl=1.15.7-00

Hold them at the current version:

$ sudo apt-mark hold docker-ce kubelet kubeadm kubectl

Add the iptables rule to sysctl.conf:

$ echo "net.bridge.bridge-nf-call-iptables=1" | sudo tee -a /etc/sysctl.conf

Enable iptables immediately:

$ sudo sysctl -p

Initialize the cluster (run only on the master):

$ sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Set up local kubeconfig (run only on the master):

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

Apply Flannel CNI network overlay (run only on the master) :

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Join the worker nodes to the cluster:

$ sudo kubeadm join [your unique string from the kubeadm init command]

Verify the worker nodes have joined the cluster successfully:

$ kubectl get nodes

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