kubeadm installation

• kubeadm cluster setup Refer Here

 kubeadm init --pod-network-cidr=10.244.0.0/16 --cri-socket unix:///var/run/cri-dockerd.sock

• Once the command is succesful you would get and output

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 172.31.9.186:6443 --token oc7nyd.g36rl6lycyk15ywl \
        --discovery-token-ca-cert-hash sha256:ef3f2b626d6168b4d2cbb64a044285def92423aa312f37405d49adb31a356815

• To run kubernetes as a non root user on control plane

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

• The network of the kuberentes is CNI is implemented by many providers Refer Here
• When the manual installation of k8s is done, most of the organizations prefer flannel Refer Here

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

• Now login into the node 1 and become a root user and then execute

kubeadm join 172.31.9.186:6443 --token oc7nyd.g36rl6lycyk15ywl \
        --discovery-token-ca-cert-hash sha256:ef3f2b626d6168b4d2cbb64a044285def92423aa312f37405d49adb31a356815

• Now perform the same on the node 2 by executing the same command shown below as a root user

kubeadm join 172.31.9.186:6443 --token oc7nyd.g36rl6lycyk15ywl \
        --discovery-token-ca-cert-hash sha256:ef3f2b626d6168b4d2cbb64a044285def92423aa312f37405d49adb31a356815

• Now login into master/control plane and execute kubectl get nodes
  

Kubernetes playground

• Login into kubernetes playground Refer Here and create two nodes
• On the node which you choose as control plane/master execute the following commands

You can bootstrap a cluster as follows:

 1. Initializes cluster master node:

 kubeadm init --apiserver-advertise-address $(hostname -i) --pod-network-cidr 10.5.0.0/16


 2. Initialize cluster networking:

kubectl apply -f https://raw.githubusercontent.com/cloudnativelabs/kube-router/master/daemonset/kubeadm-kuberouter.yaml

* Now join the node2 to cluster and once its done, login into control plane and execute the below commands

Kubectl cheatsheet

• Refer Here
• Set autocompletion
  

kubectl

• This is official k8s client
• Checking cluster status kubectl version
  
• To check whether your cluster is healthy kubectl get componentstatuses
  
• kubectl has two primary commands to obtain information
  • get
  • describe
    
    

kube-proxy

• kube proxy is responsibe for routing network traffic in the k8s cluster. To do this job, the proxy should be present on all the nodes in the cluster
  

kuberenetes DNS

• kuberentes also runs a DNS server, which provides naming and discovery for the services in k8s cluster
  
• There is also a k8s service that performs load balancing for the DNS server
  

Note: As of now we are using kubectl from the control plane i.e we login into control plane and use kubectl, when we start using k8s as a service i.e on cloud we would setup kubectl on any machine from where we want to deploy applications.