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manage-kubeadm.md

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How do I find the join command for kubeadm on the master?

kubeadm token create --print-join-command

Here is a bash script that automate this task

read -p 'master ip address : ' ipaddr
sha_token = "$(openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //')"
token = "$(kubeadm token list | awk '{print $1}' | sed -n '2 p')"
echo "kubeadm join $ipaddr:6443 --token=$token --discovery-token-ca-cert-hash sha256:$sha_token"

Check API Version of Kubernetes

kubectl api-resources | grep pods

Continuously watching kubernetes all services

watch kubectl get all -o wide

List of Kubernetes Nodes:

kubectl get nodes

View cluster events

kubectl get events

View the kubectl configuration

kubectl config view

Accessing Kubernetes Dashboard

Installing the Kubernetes Dashboard

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.7.0/aio/deploy/recommended.yaml

List of Namespaces

kubectl get services --all-namespaces

Check all the resources

kubectl get all -n kubernetes-dashboard

Accessing the Kubernetes Dashboard from Outside

Easy Ways

Port Forwarding for kubernetes-dashboard

kubectl port-forward -n kubernetes-dashboard service/kubernetes-dashboard 10443:443 --address 0.0.0.0

Browsing Kubernetes-Dashboard

https://192.168.0.89:10443

Another Ways

We will have to change the type of service from ClusterIp to NodePort. So, give the following command to edit the service and make the following changes.

kubectl edit service/kubernetes-dashboard -n kubernetes-dashboard

After: You can give the IP of your wish if 32321 is occupied

Now, check if the service was changed successfully by giving the following command:

kubectl get svc

It will open the Kubernetes dashboard in the web browser.

kubectl proxy --address='0.0.0.0' --disable-filter=true
kubectl proxy --address='0.0.0.0' --accept-hosts='^$'
kubectl proxy --address='0.0.0.0' --port=8001 --accept-hosts='^$' 

kubectl -n kubernetes-dashboard describe service kubernetes-dashboard

Deploy a simple Nginx POD

kubectl create deployment nginx-web --image=nginx


kubectl expose deployment nginx-web --type NodePort --port=80


kubectl get deployment,pod,svc

Create Nginx POD using YAML file

nano nginx.yaml


apiVersion: v1 
kind: Pod 
metadata:
  name: nginx-pod 
spec:
  containers:
  - name: nginx 
    image: nginx:latest 
    ports:
    - containerPort: 80 


kubectl apply -f nginx.yaml

Kubectl Port-Forwarding Syntax

Port-Forward Syntax

kubectl port-forward POD_NAME LOCAL_PORT:REMOTE_POD_PORT

Command Description

POD_NAME: Give our pod name.
LOCAL_PORT: Give a port which we access from the internet.
REMOTE_POD_PORT: Give our pods default port.

Example:

kubectl port-forward nginx-pod 8085:80 --address 0.0.0.0

Kubectl port-forward in background

kubectl port-forward nginx-pod 8085:80 &


kubectl port-forward nginx-pod 8085:80 --address 0.0.0.0 &

Port-Forwarding a local port to a pod with address binding:

kubectl port-forward --address :

Example command:

kubectl port-forward --address 192.168.0.100 my-pod 8080:80

Forwarding a local port to a service with address binding:

kubectl port-forward --address service/ :

Example command:

kubectl port-forward --address 192.168.0.100 service/my-service 8080:80

Listen on a random port locally, forwarding to 80 in the pod

kubectl port-forward pod/nginx :80

Check port-forwarding services

ps -ef | grep port-forward

Analyze Network Connections

netstat -antp

Kubectl Basic Operation in Kubernetes

Run a Pod

kubectl run nginx -–image nginx

Port-forwarding the pod

kubectl port-forward nginx 8080:80

View the Pod Logs

kubectl logs nginx

View the Pod Logs Continuously

kubectl logs -f pod-name

Run a Pod with Shell Exection

kubectl run myshell -it –image busybox –sh

Run a Pod with Shell Exection and auto delete pods

kubectl run myshell —rm –it –image busybox –sh

Execute command from outside to the inside pods

kubectl exec pod-name date

Execute command from outside to the inside pods

kubectl exec pod-name -c container-name date

Execute pods

kubectl exec -it pod-name /bin/bash

Delete Pods

kubectl delete pod myportfolio

Delete all Pods

kubectl delete pods –all

Delete pods & services using label name

kubectl delete pods,services -l name=label-name

View Description

kubectl describe pod nginx

Create a Deployment

kubectl create deployment nginx --image nginx:latest --replicas 3

List of Deployments

kubectl get deployment

Scale a Deployment

kubectl scale deployment nginx --replicas 5

Delete Deployment

kubectl delete deploy myshell

Create a pod using local docker images using image-policy

kubectl run myportfolio --image=myportfolio:latest --image-pull-policy=Never --restart=Never

Expose a Service

kubectl expose deployment nginx –type NodePort –port 80

View Service Description

kubectl describe svc ngnix

List of pods widely

kubectl get pods -o wide

Create a Namespace

kubectl create namespace devops-tool-suite

Kubernetes Persistent Volumes using HostPath

Check your cluster’s storage classes

kubectl get storageclass

Create a Persistent Volume

nano nginx-hostpath.yaml


apiVersion: v1
kind: PersistentVolume
metadata:
  name: nginxpv
spec:
  accessModes:
    - ReadWriteOnce
  capacity:
    storage: 1Gi
  storageClassName: standard
  hostPath:
    path: /nfsstorage/nginxdata

---
#Create a Persistent Volume Claim

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nginxpvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: standard
  volumeName: nginxpv
  
---
#Attach PVCs to Pods

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - name: nginx
      image: nginx:latest
      volumeMounts:
          name: data
        - mountPath: /usr/share/nginx/html
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: nginxpvc


kubectl create -f nginx-hostpath.yaml


kubectl get pv,pvc,pod

Kubernetes Persistent Volumes using NFS

nano nginx-nfs.yaml


apiVersion: v1
kind: PersistentVolume
metadata:
  name: mynfspv
spec:
  capacity:
    storage: 2Gi
  accessModes:
    - ReadWriteOnce
  nfs:
    server: 192.168.0.96
    path: /nfsstorage/jenkins_home
  persistentVolumeReclaimPolicy: Retain

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mynfspvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi
---
#Attach PVCs to Pods

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
    - name: nginx
      image: nginx:latest
      volumeMounts:
          name: data
        - mountPath: /usr/share/nginx/html
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: mynfspvc


kubectl create -f nginx-nfs.yaml


kubectl get pv,pvc,pod

Jenkins Deployment in Kubernetes

nano jenkins-k8s.yaml


apiVersion: apps/v1
kind: Deployment
metadata:
  name: myjenkins
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myjenkins
  template:
    metadata:
      labels:
        app: myjenkins
    spec:
      containers:
      - name: myjenkins
        image: jenkins/jenkins:lts
        ports:
          - name: http-port
            containerPort: 8080
          - name: jnlp-port
            containerPort: 50000
        #command: ["sh", "-c", "chown -R 777:777 /var/jenkins_home"]
        #command: ["sh", "-c", "chown root:root /var/jenkins_home"]
        volumeMounts:
          - name: jenkins-home
            mountPath: /var/jenkins_home
      volumes:
          - name: jenkins-home
            persistentVolumeClaim:
             claimName: pvcnfs


kubectl create -f jenkins-k8s.yaml


kubectl get pod

Verifying Kubernetes Volume

Verifying Storage Class List

kubectl get sc

Describe Specefic Storage Class

kubectl describe sc StorageClass-Name

Verifying Persistent Volume List

kubectl get pv

Verifying Persistent Volume Claim List

kubectl get pvc

Describe Specefic Persistent Volume

kubectl describe pv pv-name

Describe Specefic Persistent Volume Claim

kubectl describe pvc pvc-name

Delete Specefic Storage Class

kubectl delete sc sc-name

Delete Specefic PVC

kubectl delete pvc pvc-name

Delete Specefic PV

kubectl delete pv pv-name

Run Nginx Pod using NFS Data Persistent

nano nginx-nfs.yaml

apiVersion: v1 
kind: Pod 
metadata:
  name: web1 
spec:
  containers:
  - name: nginx 
    image: nginx:latest 
    ports:
    - containerPort: 80 
    volumeMounts:
      - mountPath: /usr/share/nginx/html
        name: nginxstorage
  volumes:
    - name: nginxstorage
      nfs:
        server: 192.168.0.96
        path: /nfs-share/kubernetes

Create yml file using image-pull-policy=Never

nano pod-localimage.yaml


apiVersion: v1
kind: Pod
metadata:
  name: web1
spec:
  containers:
  - name: myportfolio
    image: myportfolio:latest
    imagePullPolicy: Never
    ports:
    - containerPort: 80
    volumeMounts:
      - mountPath: /usr/share/nginx/html
        name: nginxstorage
  volumes:
    - name: nginxstorage
      nfs:
        server: 192.168.0.96
        path: /nfs-share/kubernetes