#!/bin/sh

if [ "$(id -u)" -ne 0 ]; then
    echo "This script should be run as root. Aborting..." > /dev/stderr
    exit 1
fi

#
# Following this guide: https://kubernetes.io/docs/tasks/tools/install-kubectl/
#

echo "Updating apt package index..."
apt-get update > /dev/null

echo "Installing prerequisites..."
apt-get -q -y -o Dpkg::Use-Pty=0 install apt-transport-https gnupg2 curl

echo "Adding Kubernetes' repo key..."
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -

echo "Adding Kubernetes repo..."
echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | tee -a /etc/apt/sources.list.d/kubernetes.list

echo "Updating apt package index again..."
apt-get update > /dev/null
echo "Installing 'kubectl'..."
apt-get -q -y -o Dpkg::Use-Pty=0 install kubectl

# TODO: the command `kubectl cluster-info` gives an error and the script
#       provided from the docs gives an error. In the docs they are make
#       some sort of assumption that I cannot still figure out.
#       Ffs this is an entry level doc and they already start to omit not
#       obvious stuff... sorry for not owning a magic crystal ball. >:(

# THIS, is a quality doc:
# https://www.valent-blog.eu/2019/01/01/installare-kubernetes-in-debian-9/
# The lines below comes from this doc.

echo "Installing 'kubelet' and 'kubeadm'..."
apt-get -q -y -o Dpkg::Use-Pty=0 install kubelet kubeadm

echo "Marking in hold the packages 'kubectl', 'kubelet' and 'kubeadm' in order to prevent them to update in the future..."
apt-mark hold kubelet kubeadm kubectl

echo "Reloading systemd and restarting 'kubelet' service"
systemctl daemon-reload
systemctl restart kubelet

# I guess these are the base images of kubernetes (?)
echo "Pulling some base images.."
kubeadm config images pull

echo "Initializing kubernetes.."
kubeadm init

echo "Adding kubernetes config to this user home folder (useful for non-root users)..."
mkdir -p "$HOME/.kube"
cp -i /etc/kubernetes/admin.conf "$HOME/.kube/config"
chown "$(id -u)":"$(id -g)" "$HOME/.kube/config"

# This last one thanks to:
# https://stackoverflow.com/questions/53814150/how-to-setup-a-2-node-kubernetes-cluster-in-custom-environment

echo "export KUBECONFIG=/etc/kubernetes/admin.conf" | tee -a ~/.bashrc