Kubernetes Master Node

# INSTALL KUBERNETES ON CENTOS 7

# Step 1: Prepare Hostname, Firewall and SELinux
# master-node ganti sesuai nama hostname atau nama hostname diganti menjadi master-node
sudo vi /etc/hosts
10.128.0.27 master-node
10.128.0.29 node-1 worker-node-1
10.128.0.30 node-2 worker-node-2

# You can ping worker-node-1 and worker-node-2 to test (100% lost)
ping 10.128.0.29
ping 10.128.0.30

# disable SElinux and update your firewall rules
sudo setenforce 0
sudo sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux
sudo reboot

# Set the following firewall rules on ports
sudo firewall-cmd --permanent --add-port=6443/tcp
sudo firewall-cmd --permanent --add-port=2379-2380/tcp
sudo firewall-cmd --permanent --add-port=10250/tcp
sudo firewall-cmd --permanent --add-port=10251/tcp
sudo firewall-cmd --permanent --add-port=10252/tcp
sudo firewall-cmd --permanent --add-port=10255/tcp
sudo firewall-cmd --reload
sudo modprobe br_netfilter

# pastikan isinya 1, jika tidak edit
echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables

# Step 2: Setup the Kubernetes Repo
sudo vi /etc/yum.repos.d/kubernetes.repo

[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
EOF

# Step 3: Install Kubeadm and Docker
sudo yum install kubeadm docker -y

# When the installation completes successfully, enable and start both services
sudo systemctl enable kubelet
sudo systemctl start kubelet
sudo systemctl enable docker
sudo systemctl start docker

# Step 4: Initialize Kubernetes Master and Setup Default User
# disable swap in order to run “kubeadm init“ command
sudo swapoff -a

# Initializing Kubernetes master is a fully automated process that is managed by the “kubeadm init“ command which you will run
sudo kubeadm init # tambahkan --pod-network-cidr=10.244.0.0/16 jika akan install flanel

# jika error pastikan hostname di dns disesuaikan, buka port 6443 dan 10250 di firewall
# jika ingin mereset/mengulang kubeadm init
kubeadm reset

# contoh setelah init catat baris terakhir (You may want to copy the last line and save it somewhere because you will need to run it on the worker nodes.)
sudo kubeadm join 10.128.0.27:6443 --token fyllch.1b6jl7p6azn16rfr \
    --discovery-token-ca-cert-hash sha256:68f2b4540eaf8794b5296f40289bf4325cec0045b885b863ae55f19ddb4b4ca2

# jika join error dir not empty, tambahkan parameter
--ignore-preflight-errors=All

# bila lupa kode join bisa ketik perintah berikut
kubeadm token create --print-join-command

# jika error di centos (Centos Docker runs in cgroupfs while kubelet runs in systemd cgroup), ubah group docker ke systemd
# lihat cgroup docker
docker info | grep -i cgroup
sudo vi /etc/docker/daemon.json

{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2",
  "storage-opts": [
    "overlay2.override_kernel_check=true"
  ]
}

sudo mkdir -p /etc/systemd/system/docker.service.d

# Restart Docker
systemctl daemon-reload
systemctl restart docker

# Having initialized Kubernetes successfully, you will need to allow your user to start using the cluster, To use a sudo enabled user:
sudo mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# Now check to see if the kubectl command is activated
kubectl get nodes

# At this point, you will also notice that the status of the master-node is ‘NotReady’.
# This is because we are yet to deploy the pod network to the cluster
# The pod Network is the overlay network for the cluster, that is deployed on top of the present node network.
# It is designed to allow connectivity across the pod.

# Step 5: Setup Your Pod Network
# These commands will be important to get the pod network setup
export kubever=$(kubectl version | base64 | tr -d '\n')
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$kubever"

# Now if you check the status of your master-node, it should be ‘Ready’
kubectl get nodes

# note: jika setelah reboot service kubelet tidak jalan
# swap off, join ulang
# kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$kubever"
# untuk network selain weave bisa gunakan flanel (documentation network https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network)

# install ulang, sebelum init, hapus config di $HOME/.kube/config
sudo rm $HOME/.kube/config
sudo rm $HOME/.kube/config.old