Kubernetes-learning

DAY 1

Introduction Why & What ? Benefits of Kubernetes Compare with other container orchestrator engine minikube intoduction & setup

DAY 2

DAY 3

How to run

pod.yml

make sure minikube is running -> if not run "minikube start" then run "kubectl apply -f pod.yml" to check status "kubectl get po welcom-pod" to get detailed info "kubectl describe po welcome-pod" to delete the pod "kubectl delete po welcome-pod"

initcontainer-nodeapp.yml

kubectl apply -f initcontainer-nodeapp.yml

kubectl get po foss-app-with-init

kubectl describe po foss-app-with-init

kubectl delete -f initcontainer-nodeapp.yml

Day 4

ReplicationController | ReplicaSet | Deployment

ReplicationController

kubectl apply -f replication.yml kubectl describe replicationcontrollers/nginx kubectl describe rc nginx kubectl delete replicationcontrollers/nginx

List on which node pods are running inside cluster (Since I am using minikube, we'll find no change in node) kubectl get po -o wide

To list all available nodes. (Since working on minikube only one node i.e minikube will be visible) kubectl get nodes

Scale up

• useful when traffic increases on application.

kubectl describe rc nginx Observe the replicas

kubectl scale rc nginx --replicas=5 kubectl describe rc nginx Observe the changes.

kubectl get rc nginx This will show desired and current state with ready as well.

ReplicaSet

kubectl apply -f replicaSet-MatchExpression.yml kubectl get pods kubectl get rs nginx-rs -o wide kubectl describe rs nginx-rs

kubectl scale rc nginx-rs --replicas=6 kubectl get pods -o wide kubectl get po -l app=nginx-app

Diff b/w ReplicaController and ReplicaSet

• ReplicaController supports only Euaility based Selectors Operators -> ( = , == , !=) kubectl get pods -l app=nginx

• ReplicaSet Supports Equality based and Set based selectors. Operators -> ( in , notin , exists)

Deployment

kubectl create -f deployement.yml kubectl apply -f deployement.yml kubectl describe deploy nginx-deploy kubectl get po -l app=nginx-app

• Update version of nginx

Way 1

kubectl set image deploy nginx-deploy nginx-container=nginx:1.9.1

Way 2

kubectl edit deploy nginx-deploy

What if by mistake we did this nginx-container=nginx:1.91 insted of nginx-container=nginx:1.9.1 -- It will get stucked -- We need to do rollback to previous stable release kubectl set image deploy nginx-deploy nginx-container=nginx:1.91 kubectl set image deploy nginx-deploy nginx-container=nginx:1.91 --record -- with --record K8s will record this command in resource annotation kubernetes.io/change-cause

knoldus@nitin-knoldus:~/Desktop/KubernetesResources/Kubernetes-learning/Day4-Replicas/DocExamples$ kubectl rollout status deployment/nginx-deploy Waiting for deployment "nginx-deploy" rollout to finish: 1 out of 3 new replicas have been updated...

kubectl rollout history deployment/nginx-deploy kubectl rollout undo deployment/nginx-deploy kubectl rollout status deployment/nginx-deploy

• Scale up and Scale down kubectl scale deployment nginx-deploy --replicas=5 kubectl get deploy kubectl get po

kubectl scale deployment nginx-deploy --replicas=1 kubectl get deploy kubectl get po -l app=nginx-app

<<<<<<< HEAD

Commands

label the node

• kubectl label nodes minikube newlabel=minilabel

watch

• watch kubectl get pods -n my-name

create

• kubectl create -f pod.yml -n my-name

apply

• kubectl apply -f pod.yml -n my-name

get

• kubectl get pods -n my-name

describe

• kubectl describe pods mypod -n my-name

wide

• kubectl get pods -n my-name -o wide

delete

• kubectl delete pods mypod -n my-name

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