kubernetes.txt

>>>>>>> Kubernetes <<<<<<<<<
Basic Commands
Minikube    
KubeCTL 
Create YML File
Microk8s CMDS
-------------------------------------------------

Basic Commands : 

0. Display all list (pods,services,deployments & riplicaSets)
   kubectl get all --all-namespaces  
   microk8s enable dns storage           //Use add-ons
  
 
1. Run a yamal file

   //Output redirect to new yaml file
   kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom -o yaml > mysecondpd.yml
  
   kubectl create -f firstpod.yml --dry-run
   kubectl apply -f firstpod.yml
   cat myfirstpod.yml
   kubectl create -f firstpod.yml

2. Pods
   kubectl get pods
   kubectl delete pod myfirstpod
   kubectl explain pod --recursive !less
 
   kubectl run secondpod --generator=run-pod/v1 --image=coolgaurab147/nginx-custom
   //Client side run 
   kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom
   kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom -o yaml
 
 
3. Services
   kubectl get services
   
4. Deployment

   kubectl get pods
   kubectl create deployment <deploymentName> --image=nginx
   kubectl create deployment <deploymentName> --image=mysql --replicas=2
   kubectl scale deployment <deploymentName> --replicas=1
   kubectl get deployments
   kubectl get deployments -o wide
   kubectl get deployments -o yaml 
   kubectl get deployments -o json
   kubectl describe deployment
   kubectl describe deployment <deploymentName>
   kubectl rollout undo deployment <deploymentName> --to-revision=1
 
-------------------------------------------------

What is Minicube
Minikube installation steps in windows
How to deploy first spring boot application to Kubernetes

-------------------------------------------------
-------------------------------------------------

Installatioin: 

1. Minikube     (  )
2. KubeCTL      (  )

Requirements:

  1. Virtual Box Or Hiper-V or docker ( as a driver )
  
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--------------------------------------------------

1. Minikube Installation ( minikube.exe )
   Usually used to run k8s cluster in your local machine/computer.
   Minikube runs a single-node Kubernetes cluster on your machine so that you can try out Kubernetes for your daily development work.
   Minikube is a lightweight Kubernetes implementation that creates a VM on your local machine and deploys a simple cluster containing only one node.

2. KubeCtl Installation ( Kubectl.exe )

	kubectl. The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs. For more information including a complete list of kubectl operations, see the kubectl reference documentation.

# Download minikube & kubectl
# Install first minikube second kubectl
# Path to environment variable  ( kubectl & minikube )
# 
# Open cmd write command 
	> minikube start --driver=docker
    > minikube status
    > kubectl cluster-info
    > kubectl get node

    Now install spring boot project
    > minikube docker-env
    > copy the above command showing @FOR /F %1 ('minikube -p minikube docker-env') Do @i
    > docker images
    > ........... more

-------------------------------------------------------------------
-------------------------------------------------------------------
//Creating first yml file 
MyFirst Yaml File:

apiVersion: 
kind: 
metadata:
spec:


apiVersion: v1
kind: Pod

metadata:
 name: myfirstpod
 labels: 
  env:prod
  
spec:
 containers:
  - name: containername
    image: coolgaurab147/nginx-custom
        
    
Run Yamal File: 
 kubectl create -f firstpod.yml --dry-run
 cat myfirstpod.yml
 kubectl create -f firstpod.yml
 kubectl get pods
 kubectl explain pod --recursive !less
 
 //Create k8s pod
 kubectl run secondpod --generator=run-pod/v1 --image=coolgaurab147/nginx-custom
 //Client side run 
 kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom
 kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom -o yaml
 
 //Output redirect to new yaml file
  kubectl run secondpod --dry-run --generator=run-pod/v1 --image=coolgaurab147/nginx-custom -o yaml > mysecondpd.yml
    
  Commands: 
  kubectl get pods
  kubectl delete pods myfirstpod
  ls
  kubectl apply -f mysecond.yml    //Create pod   
 
 Example YML File: 
 apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80 
 
--------------------------------------------

 >>> Microk8s CMDS <<<<<<
 
 sudo snap install microk8s --classic --channel=1.25   //Install MicroK8s
 sudo usermod -a -G microk8s $USER                    //Join the group
 sudo chown -f -R $USER ~/.kube
 su - $USER                                           // Password
 microk8s status --wait-ready                         //Check the status
 microk8s kubectl get nodes                          //Access Kubernetes
 microk8s kubectl get services
 alias kubectl='microk8s kubectl'
 
 microk8s kubectl create deployment nginx --image=nginx //Deploy an app
 microk8s kubectl get pods
 
 microk8s enable dns storage           //Use add-ons
 
  //microk8s
  microk8s stop
  microk8s start
  microk8s status
  microk8s kubectl get all --all-namespaces
  microk8s kubectl get pods
  microk8s kubectl create deployment <deploymentName> --image=nginx
  microk8s kubectl create deployment <deploymentName> --image=mysql --replicas=2
  microk8s kubectl scale deployment <deploymentName> --replicas=1
  microk8s kubectl get deployments
  microk8s kubectl get deployments -o wide
  microk8s kubectl get deployments -o yaml 
  microk8s kubectl get deployments -o json
  microk8s kubectl describe deployment
  microk8s kubectl describe deployment <deploymentName>
  microk8s kubectl rollout undo deployment <deploymentName> --to-revision=1
 
--------------------------------------------
//In Pod's container
kubectl get pods
kubectl exec <podName> env
kubectl exec <podName> -c <containerName> env
kubectl exec <podName> 
kucbctl get pods
kubectl exec <podName> <containerName> -it bash
kubectl exec <podName> -c <containerName> -it bash
kubectl exec <podName> -c <containerName> -it ls /   

Some CMDS: 
kubectl expose pod <podName>
kubectl get pod
kubectl expose pod <podname> --port=8000 --target=80 --name <serviceName>
kubectl get services
kubectl get svc
curl 10.88.20e.56:8000

//Mulit containers in a pod (shared network)
kubectl get pods
kubectl apply -f firstpod.yml
kubectl get pods

kubectl grep name firstpod.yml
kubectl exec myfirstpod -c firstcontainer -it bash
netstat -nltp
netcat -l -p 8000  //Port listen
telnet localhost 8000
ifconfig

//initContainer (Add initContainer in above yml file)
 initContainers:
  - name: initcontainer
    image: coolgourav147/nginx-custom
    env:
     - name: myname
       value: Gaurav
     - name: City
       value: Jaipur
    args: ["sleep","3600"]
  - name: secondcontainer
    image: coolgourav147/nginx-custom  
    
kubectl apply -f firtpod.yml
kubectl get pods -w

--------------------------------------------
 Kubernetes Short Commands:  (Copied on github to kubernetes.txt page)
  
  Minikube vs Kind vs K3s
 
   
  kubectl get all
  kubectl get rs
  kubectl get ns
  kubectl get pods -n kube-system    
    
       
  Minikube: 
  minikube kubectl get all
  minikube kubectl get rs
  minikube kubectl get ns
  minikube kubectl get pods -n kube-system
       
  kind kubectl get all
  kind kubectl get rs
  kind kubectl get ns
  kind kubectl get pods -n kube-system
   
  microk8s kubectl get all
  microk8s kind kubectl get rs
  microk8s kind kubectl get ns
  microk8s kind kubectl get pods -n kube-system
    

 //Installation Minikube on ubuntu
 Minikube System Requirements

    2 GB RAM or more
    2 CPU / vCPU or more
    20 GB free hard disk space or more
    Docker / Virtual Machine Manager – KVM & VirtualBox

 Prerequisites for minikube

    Minimal Ubuntu 20.04 LTS / 21.04
    Sudo User with root privileges
    Stable Internet Connection

Step 1) Apply updates: 
        Apply all updates of existing packages of your system by executing the following apt commands,
 
   sudo apt update -y 
   sudo apt upgrade -y
  
 Once all the updates are installed then reboot your system once.
  sudo reboot
 
Step 2) Install Minikube dependencies
         Install the following minikube dependencies by running beneath command,
   sudo apt install -y curl wget apt-transport-https
 
Step 3) Download Minikube Binary
        Download Minikube latest minikube binary
        https://www.linuxtechi.com/wget-command-practical-examples/

  wget https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64

       Once the binary is downloaded, copy it to the path /usr/local/bin and set the executable permissions on it

  sudo cp minikube-linux-amd64 /usr/local/bin/minikube
  sudo chmod +x /usr/local/bin/minikube 
 
       Verify the minikube version
       
  minikube version
  minikube version: v1.27.0                          //cmd
  commit: 4243041b7a72319b9be7842a7d34b6767bbdac2b   //cmd
  
       
Step 4) Install Kubectl utility
 	Kubectl is a command line utility which is used to interact with Kubernetes cluster. It is used for managing deployments, service and pods etc. Use below curl command to download latest version of kubectl.
 
 
    curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl      //cmd
    
    
       Once kubectl is downloaded then set the executable permissions on kubectl binary and move it to the path /usr/local/bin.    
    
    
  chmod +x kubectl                      //cmd
  sudo mv kubectl /usr/local/bin/       //cmd
    
       Now verify the kubectl version    
    
  kubectl version -o yaml               //cmd 
  
 Step 5) Start minikube
         As we are already stated in the beginning that we would be using docker as base for minikue, so start the minikube with the docker driver, run 
  
  minikube start --driver=docker       //cmd
  
  
 In case you want to start minikube with customize resources and want installer to automatically select the driver then you can run following command,
 
  minikube start --addons=ingress --cpus=2 --cni=flannel --install-addons=true --kubernetes-version=stable --memory=6g      //cmd 
  
  
  
 //Run below minikube command to check status,
 
  ajay@sisaudiya:~$ minikube status
  minikube
  type: Control Plane
  host: Running
  kubelet: Running
  apiserver: Running
  kubeconfig: Configured
  pkumar@linuxtechi:~$
  -------------------------------------------------


Docker: 

Containers can not communicate each other
Auto scaling and load balancing
Was not possible 
container had to be manage carefully


Features of Kubernetes : 

Orchestration        (Clustering of any no. of containers running of different network)
Auto Scaling         (Vertically and Horizontally)
Auto Healing
Load Balancing
Plateform Independent (Cloud, Virtual, Physical)
Fault Tolerance       (node/pod failure)
Rollback              (Going back to pervious version)
Health monitoring of container
Batch Execution


ubuntu: 
netstat -nltp
netcat -l -p 8000   //To listen
telnet localhost 8000
ifconfig
Enter into container
grep name abcd.yml



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Kubernetes:  (Working)

Pod with HostPath: 

apiVersion: v1
kind: Pod
metadata:
  name: hostpath2
  labels:
    app: php-vol1    
spec:
  containers:
  - name: hostpath2
    image: astechutube/custom-php8.0-apache
    #command: ["/bin/bash", "-c", "sleep 15000"]
    volumeMounts:
     - name: testvol2
       mountPath: /var/www/html               
  volumes:
  - name: testvol2
    hostPath: 
      path: /tmp/php1 







------------------------------------------
Kubernetes:  (Working)

Deployment with hostpath

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deploy-hostpath
  labels:
    app: host-vol1
spec:
  replicas: 1
  selector:
    matchLabels:
      app: host-vol1
  template:
    metadata:
      labels:
        app: host-vol1
    spec:
      containers:
      - name: hostpath
        image: astechutube/custom-php8.0-apache
        volumeMounts:
          - name: testvolume
            mountPath: /var/www/html         
        ports:
          - containerPort: 80
      volumes:
        - name: testvolume
          hostPath: 
            path: /tmp/var/www/html



CMDS: 

 microk8s kubectl apply -f deployment3.yml
 microk8s kubectl get deployment 

---------------------------------------------