Install Kubernetes on Ubuntu 18.04 LTS & Centos

 

	Step1: On All Machines ( Master & All nodes ):
	**********************
	### INSTALL DOCKER
	sudo apt-get update
	sudo apt-get install -y apt-transport-https ca-certificates curl software-properties-common
	curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
	sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
	sudo apt-get update ; clear
	sudo apt-get install -y docker-ce
	sudo service docker start ; clear
	### INSTALL KUBEADM,KUBELET,KUBECTL
	echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
	curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
	sudo apt-get update ; clear
	sudo apt-get install -y kubelet kubeadm kubectl
	************************
	Step2: On Master only:
	***********************
	sudo kubeadm init --ignore-preflight-errors=all
	sudo mkdir -p $HOME/.kube
	sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
	sudo chown $(id -u):$(id -g) $HOME/.kube/config
	## Weave
	**********************
	kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
	kubectl get nodes
	kubectl get all --all-namespaces
	**********************
	Step3: On Nodes only:
	**********************
	copy the kubeadm join token from master & run it on all nodes
	Ex: kubeadm join 10.128.15.231:6443 --token mks3y2.v03tyyru0gy12mbt \
	--discovery-token-ca-cert-hash sha256:3de23d42c7002be0893339fbe558ee75e14399e11f22e3f0b34351077b7c4b56
	how to find kubeadm join token later
	****************************
	kubeadm token create --print-join-command --ttl=0
	## Install Kubernetes on CENTOS
	### Step1: `On All Machines ( Master & All nodes ):`
	### Set SELinux in permissive mode (effectively disabling it)
	setenforce 0
	sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
	### Install Docker
	sudo yum remove -y docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine docker-ce docker-ce-cli containerd.io
	sudo yum install -y yum-utils device-mapper-persistent-data lvm2
	sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
	sudo yum install -y docker-ce docker-ce-cli containerd.io
	systemctl enable --now docker
	systemctl start docker
	### Install kubeadm,kubelet,kubectl
	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
	yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
	systemctl enable --now kubelet
	### Step2: `On Master only:`
	sudo kubeadm init --ignore-preflight-errors=all
	sudo mkdir -p $HOME/.kube
	sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
	sudo chown $(id -u):$(id -g) $HOME/.kube/config
	## Weave Pod Network
	kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
	kubectl get nodes
	kubectl get all --all-namespaces
	### Step3: `On Nodes only:`
	copy the kubeadm join token from master & run it on all nodes
	Ex: kubeadm join 10.128.15.231:6443 --token mks3y2.v03tyyru0gy12mbt \
	--discovery-token-ca-cert-hash sha256:3de23d42c7002be0893339fbe558ee75e14399e11f22e3f0b34351077b7c4b56
	##### To Generate certificate or public key
	openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'

Create Pods with CPU Limit and Range in the default namespace

 

Pod with limit

Create a pod definition that requests for CPU more than 200m and less than 800m

vim pod-with-cpu-within-range.yml

apiVersion: v1
kind: Pod
metadata:
  name: pod-with-cpu-within-range
spec:
  containers:
  - name: pod-with-cpu-within-range
    image: nginx
    resources:
      limits:
        cpu: "800m"
      requests:
        cpu: "500m"

List the existing pods and create a new pod with the file created in the above step.

kubectl get pods

kubectl create -f pod-with-cpu-within-range.yml

kubectl get pods

kubectl describe pod pod-with-cpu-within-range