Kubernetes

This installation is for testing proposes, do not install it as a production environment.

What is Kubernetes?

Kubernetes is an open-source container-orchestration system for automating application deployment, scaling, and management. It was originally designed by Google, and is now maintained by the Cloud Native Computing Foundation. Wikipedia.

My Lab

• VMware Workstation;
• CentOS 7;
• 1 Master Nodes;
• 2 Worker Nodes (Minions);
• Windows Server as my DNS Server.

2 vCPU | 4GB Memory | 20GB Disk

Master

• chlabk8sm01.chlab.local - 192.168.255.33/24

Node

• chlabk8sm01.chlab.local - 192.168.255.33/24
• chlabk8sm02.chlab.local - 192.168.255.34/24

Prerequisites

Before you start creating your Kubernetes cluster, We need to prepare whole virtual machines (Master and Nodes).

• Name;
• IP/DNS/GATEWAY;
• Yum update;
• Disable SELINUX;
• Disable SWAP;
• Allow Firewall Rules;
• Create DNS (A).
• All commands will be run in root "sudo su -"

Let's Go!

Default Steps (All Servers)

DISABLE SWAP

swapoff -a 

Edit the file /etc/fstab and comment the line below with #

**#**/dev/mapper/centos-swap swap                    swap    defaults        0 0

save the file and back to the shell - If swap is not disabled, kubelet service will not start on the masters and nodes, for Platform9 Managed Kubernetes version 3.3 and above.

Allow Firewall Rules

firewall-cmd --permanent --add-port=2379-2380/tcp

firewall-cmd --permanent --add-port=6443/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 --reload

modprobe br_netfilter

echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables

Configure DNS

I am using Windows Server as a DNS Server.

In master server edit the file /etc/resolv.conf

vi /etc/resolv.conf and type your DNS

Example:
search chlab.local #(It's my domain)
nameserver 192.168.255.10 #(It's my IP domain server)

Disable SELINUX

setenforce 0

sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux

After that, reboot your servers.

Configure 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	 
EOF

Install Kubeadm

yum install kubeadm -y

Install Docker

yum install docker -y

Enable and Start Kubelet

systemctl restart kubelet && systemctl enable kubelet

Enable and Start Docker

systemctl restart docker && systemctl enable docker

MASTER STEPS

INITIALIZE KBERNETES MASTER

kubeadm init --pod-network-cidr=192.168.255.0/24

RUNNING THE INSTTRUCTIONS

As you can see in your screen, we need to run these commands:

mkdir -p $HOME/.kube
-i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config

Deploy Pod Network

kubectl apply -f https://docs.projectcalico.org/v3.7/manifests/calico.yaml

COPY THE LINE (This line will be different for my)

kubeadm join 192.168.255.33:6443 --token vj3ror.foc4ijc3uy3ep1mf \
    --discovery-token-ca-cert-hash sha256:96f45bdd8c9408d7bb84f5ff6e661b1b0906496a172a49e17a2cd5ed0d6f73e2

NODE STEP

kubeadm join 192.168.255.33:6443 --token vj3ror.foc4ijc3uy3ep1mf \
    --discovery-token-ca-cert-hash sha256:96f45bdd8c9408d7bb84f5ff6e661b1b0906496a172a49e17a2cd5ed0d6f73e2

Get Nodes

To list your nodes:

kubectl get nodes

DONE

If you followed all tips and didn't skip anything you probably had success.