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Kubernetes_Setup_using_kubeadm.md

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Kubernetes Cluster installation using kubeadm

Follow this documentation to set up a Kubernetes cluster on CentOS 7 machines.

This documentation guides you in setting up a cluster with one master node and two worker nodes.

Prerequisites:

  1. System Requirements

    Master: t2.medium (2 CPUs and 2GB Memory)
    Worker Nodes: t2.micro

  2. Open Below ports in the Security Group.

    Master node:

    6443 32750 10250 4443 443 8080

    On Master node and Worker node:

    179

    On Master and Worker:

  3. Perform all the commands as root user unless otherwise specified

    Install, Enable and start docker service. Use the Docker repository to install docker.

    If you use docker from CentOS OS repository, the docker version might be old to work with Kubernetes v1.13.0 and above

    yum install -y -q yum-utils device-mapper-persistent-data lvm2 > /dev/null 2>&1
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo > /dev/null 2>&1
yum install -y -q docker-ce >/dev/null 2>&1

  4. Start Docker services

    systemctl enable docker
systemctl start docker

  5. Disable SELinux

    setenforce 0
sed -i --follow-symlinks 's/^SELINUX=enforcing/SELINUX=disabled/' /etc/sysconfig/selinux

  6. Disable Firewall

    systemctl disable firewalld
systemctl stop firewalld

  7. Disable swap

    sed -i '/swap/d' /etc/fstab
swapoff -a

  8. Update sysctl settings for Kubernetes networking

    cat >> /etc/sysctl.d/kubernetes.conf <<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

Kubernetes Setup

  1. Add yum repository for kubernetes packages 
    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
EOF
  2. Install Kubernetes 
    yum install -y kubeadm kubelet kubectl
  3. Enable and Start kubelet service 
    systemctl enable kubelet
systemctl start kubelet

On Master Node:

  1. Initialize Kubernetes Cluster

    kubeadm init --apiserver-advertise-address=<MasterServerIP> --pod-network-cidr=192.168.0.0/16

  2. Create a user for kubernetes administration and copy kube config file.
    To be able to use kubectl command to connect and interact with the cluster, the user needs kube config file.
    In this case, we are creating a user called kubeadmin

    useradd kubeadmin 
mkdir /home/kubeadmin/.kube
cp /etc/kubernetes/admin.conf /home/kubeadmin/.kube/config
chown -R kubeadmin:kubeadmin /home/kubeadmin/.kube

  3. Deploy Calico network as a kubeadmin user.

    This should be executed as a user (heare as a kubeadmin )

    sudo su - kubeadmin 
curl https://docs.projectcalico.org/manifests/calico-typha.yaml -o calico.yaml
kubectl apply -f calico.yaml

  4. Cluster join command

    kubeadm token create --print-join-command

On Worker Node:

  1. Add worker nodes to cluster

    Use the output from kubeadm token create command in previous step from the master server and run here.

  2. Verifying the cluster To Get Nodes status

    kubectl get nodes

    To Get component status

    kubectl get cs