Kubernetes

Installation on Ubuntu 18.04 AMD64

#apt-get update -y && apt-get upgrade -y


curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://apt.kubernetes.io/ kubernetes-xenial main
EOF
apt-get update && apt-get install -y kubelet kubeadm kubectl

To initiate master node

#kubeadm init --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12

If you get NumCPU Error , use this

`#kubeadm init --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=NumCPU`

You will get a join token in end. Keep that handy

On worker node , paste that token you copied

kubeadm join 172.31.31.222:6443 --token vjdts6.2dil5zuceqq22x6h --discovery-token-ca-cert-hash sha256:0dfda522f1d622effda0883c30aa21fe05b246552f10d64ecd60db0ccb3a0793

Once you the installation completes, you can run below command on kubenetes Master:

kubectl get nodes

Output will be as follows:

root@ip-172-31-31-14:/home/ubuntu# kubectl get nodes
NAME              STATUS     ROLES    AGE    VERSION
ip-172-31-31-14   NotReady   master   113s   v1.13.4

You can see that STATUS is NotReady, this is because you need networking also for kubelet to handle resources on worker node. Run below command to install networking plugin. There are number of networking plugins available and you can choose any of the, We will use flannel.

Run below commands on K8s Master to install Calico plugin::

 #kubectl apply -f https://docs.projectcalico.org/v3.5/getting-started/kubernetes/installation/hosted/etcd.yaml
 #kubectl apply -f https://docs.projectcalico.org/v3.5/getting-started/kubernetes/installation/hosted/calico.yaml

Run kubectl get pods --all-namespaces on Master node to see if all pods are in running state. Once all are up, run kubectl get nodes to see if Master node is Ready

root@ip-172-31-31-14:/home/ubuntu/kube/yaml# kubectl get nodes
NAME              STATUS   ROLES    AGE   VERSION
ip-172-31-31-14   Ready    master   11m   v1.13.4

Important points to remember

1. 99.9 %, we will only use kubectl command and from Master node only
2. We will never touch Worker node once we join to Master and will work from Master only.
3. kubeadm init to initiate master node, kubeadm join to join worker node in cluster.