setup-k8s-master-redhat.sh

#!/bin/bash

# Author      : BALAJI POTHULA <balaji.pothula@techie.com>,
# Date        : 20 June 2019,
# Description : k8s-master setup on rhel.

# setting hostname.
# hostnamectl set-hostname 'k8s-master'

# executing bash.
# exec bash

# setting selinux in permissive mode,
# i.e switching off selinux enforcement
# temporarily until the machine is rebooted.
setenforce 0

# setting selinux in permissive mode,
# i.e switching off selinux enforcement
# permanently (rebooted required).
sed -i --follow-symlinks 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

# installing firewall management tool. 
yum -y install firewalld

# starting firewalld service.
systemctl start firewalld

# enabling firewalld service auto-start at system boot.
systemctl enable --now firewalld

# opening a ports.
firewall-cmd --permanent --add-port=6443/tcp
firewall-cmd --permanent --add-port=2379-2380/tcp
firewall-cmd --permanent --add-port=10250/tcp
firewall-cmd --permanent --add-port=10251/tcp
firewall-cmd --permanent --add-port=10252/tcp
firewall-cmd --permanent --add-port=10255/tcp

firewall-cmd --permanent --add-port=8001/tcp

firewall-cmd --permanent --add-port=6783/tcp
firewall-cmd --permanent --add-port=6783/udp
firewall-cmd --permanent --add-port=6784/udp

# reloading firewall.
firewall-cmd --reload

# adding br_netfilter module from kernel.
modprobe br_netfilter

# traverse iptables rules.
echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables

# disabling swap.
swapoff -a

# adding kubernetes repository.
cat > /etc/yum.repos.d/kubernetes.repo <<EOF
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
exclude=kube*
EOF

# installing kubernetes. 
yum -y install kubeadm kubernetes-cni kubelet kubectl --disableexcludes=kubernetes

# (re)starting kubelet.
systemctl restart kubelet

# run kubelet as daemon.
systemctl enable --now kubelet

# initializing kubernetes control-plane node.
kubeadm init