kubeadm installation

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# 1. Create 4 VMs - master(1) and worker(3) nodes

Node Reqs (varies depending on usage)
-------------------------------------
Master: 2 vCPUs - 6GB Ram
Worker: 1 vCPUs - 3GB RAM
OS:     CentOS/RHEL 7


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# 2. PRE-Reqs: Disable - Firewall | Swap | SELinux

# Note: Execute on all nodes (master & worker)

# Disable Firewall
systemctl stop firewalld
systemctl disable firewalld
# OR - ensure ports [6443 10250] are open

# Disable Swap
swapoff -a
sed -i.bak -r 's/(.+ swap .+)/#\1/' /etc/fstab

# Disable SELinux
setenforce 0
sed -i 's/enforcing/disabled/g' /etc/selinux/config


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3. Download & Install - Docker | Kubelet | Kubeadm | Kubectl

# Note: Execute on all nodes (master & worker)

# Kubernetes Repository
cat <<EOF > /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
exclude=kube*
EOF


# Installing Docker | Kubelet | Kubeadm | Kubectl
yum update -y
yum install -y docker kubeadm kubelet kubectl --disableexcludes=kubernetes


# Start and enable docker and kubectl
systemctl enable docker && systemctl start docker
systemctl enable kubelet && systemctl start kubelet


# For CentOS and RHEL
cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sysctl net.bridge.bridge-nf-call-iptables=1
sysctl net.ipv4.ip_forward=1
sysctl --system
echo "1" > /proc/sys/net/ipv4/ip_forward

# Restart the systemd daemon and the kubelet service with the commands:
systemctl daemon-reload
systemctl restart kubelet


Reboot the mastr and worker nodes

iptables --policy FORWARD ACCEPT



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4. Configure Kubernetes "master" node

# Initializing master node
kubeadm init --pod-network-cidr=10.240.0.0/16

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# If you want to run kubectl as "regular" user. Then, execute below.
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# Note down Join command in below step.

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# Installing Flannel network-plug-in for cluster network

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml

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


kubectl get pods --all-namespaces



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5. Join "worker" nodes to the cluster

# Get exact join command from previous kubeadm init command output.

kubeadm join 10.142.0.40:6443 --token 9xii6e.avuik4ciqrl1yacw --discovery-token-ca-cert-hash sha256:f7902e7a474d33b54f4f2fbdb4fd5e74163817e683333187736b65189ff36b7a

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kubeadm token create --print-join-command

6. Testing

# Display nodes status
kubectl get no

# Deploying sample application
kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/en/examples/controllers/nginx-deployment.yaml





# Displaying Pod status
kubectl get po -o wide


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