Kubernetes Installation and Cluster Setup

1. Installing Kubernetes
2. Setting up a Kubernetes cluster

1.1 To download and add the key to allow kubernetes installation, execute the commands mentioned below:

sudo su
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
sudo echo deb http://apt.kubernetes.io/ kubernetes-xenial main > /etc/apt/sources.list.d/kubernetes.list
 

1.2 Update the apt-get package by executing the command mentioned below:

sudo apt-get update

 

1.3 Install the kubernetes and the tools required to manage it. Run the command mentioned below in the terminal:

sudo apt install docker.io kubectl=1.20.5-00 kubeadm=1.20.5-00 kubelet=1.20.5-00
 

2.1 Update the apt-get package by executing the command mentioned below:

sudo apt-get update
 

2.2 To initialize the cluster run the following command on the master node

sudo kubeadm init
 

2.3 To start using your cluster, you need to run the following on master node:

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

2.4 You should see a single master node deployed on running the command:

sudo kubectl get nodes
 
 

2.5 Copy the kubeadm join command that you can see on the screen of your master node

2.6 Run the copied kubeadm join command as a root user on the worker node. You can use the terminal only lab as a worker node. Make sure you have Kubernetes installed on the worker node and then run the below command.

kubeadm join 172.31.64.38:6443 --token 425qb8.51rbrxc5h862g202 \
    --discovery-token-ca-cert-hash sha256:a502867d97b05820f186e3ee748afddd9142aae4104aee804d30662148138bae
 

2.7 On the master node, run the following command to install the weavenet plugin in order to create a network:

kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 |tr -d '\n')"
 

2.8 List all the nodes again to check the status of nodes using the command:

kubectl get nodes
 
 

Pod Creation in Kubernetes

1. Creating multi-container pods
2. Creating a single container pod

1.1 On the master node, create a new file named sample.yaml:

sudo su vi sample.yaml 1.2 Add the following code in the sample.yaml file:

apiVersion: v1
kind: Pod
metadata:
  name: multi-container
spec:
  terminationGracePeriodSeconds: 0
  containers:
  - name: nginx
    image: nginx:1.10-alpine
    ports:
    - containerPort: 80
  - name: alpine
    image: alpine:3.5
    command: ["watch", "wget", "-qO-", "localhost"]

1.3 Use the following command to create the multi-container pod:

kubectl create -f sample.yaml
 

2.1 On the master node, create a single container pod with a tomcat image using the following command:

kubectl run tomcat --image=tomcat:8.0
 

2.2 Check all the running pods

kubectl get pods
 

2.3 To check why exactly a pod is in the pending state, run the command

kubectl describe pods <pod_name>
 

To check why multi-container pod is pending,use the command

kubectl describe pods multi-container
 

2.4 To remove the taint from the node run the following commands:

kubectl get nodes
Copy the node name and use it in the below command
 

kubectl taint nodes node-role.kubernetes.io/master-

Here for example we use the command given below
 

kubectl taint nodes ip-172-31-18-183 node-role.kubernetes.io/master-

 
2.5	Now check the pod status. The pods should be in the running state.
 

sudo kubectl get pods