ubernetes Notes:

# kubectl get nodes

Scenario1: Creation of Pod definition file

# mkdir mynewfiles

#cd mynewfiles

# ls

# vim pod-definition1.yml

i

---

apiVersion: v1

kind: Pod

metadata:

name: nginx-pod

labels:

type: reverse-proxy

author: edureka

spec:

containers:

- name: mynginx

image: nginx

# kubectl get pods

// pod will be ready and running

# kubectl get pods -o wide

// will give more information about pods with name of slave on which pod is available.

# kubectl get nodes -o wide

Create replica Set

*******************************************

kubectl delete -f pod-definition1.yml

kubectl delete -f pod-definition2.yml

kubectl get pods

# vim rc-definition.yml

i

---

apiVersion: apps/v1

kind: ReplicaSet

metadata:

name: tomcat-rc

labels:

author: edureka

type: webserver

spec:

replicas: 3

selector:

matchLabels:

type: webserver

template:

metadata:

name: tomcat-pod

labels:

type: webserver

spec:

containers:

- name: mytomcat

image: tomcat

ports:

- containerPort: 8080

hostPort: 9090

# kubectl get pods

# kubectl get pods -o wide

# kubectl get all

*************************************************

Scaling of Pods using replica set

Method1:

Open the replica set and change replicas to 5

save the file

execute this command:

# kubectl replace -f rc-definition.yml

# kubectl get pods

now desired replicas of tomcat will be running

Method2: direct command

increase or decrese the replica count by using this command

# kubectl scale --replicas=2 -f rc-definition.yml

# kubectl get pods

//only 2 pods will be running now

For opening desired ports:

gcloud compute firewall-rules create rule1 --allow tcp:8080

gcloud compute firewall-rules create rule1 --allow tcp:9090

gcloud compute firewall-rules create rule1 --allow tcp:30008

Create nodeport service object

# vim myservice.yml

i

---

apiVersion: v1

kind: Service

metadata:

name: jenkins-service

spec:

type: NodePort

ports:

- targetPort: 8080

port: 8080

nodePort: 30008

selector:

type: webserver

# kubectl create -f myservice.yml

# kubcectl get pods

# kubectl get pods -o wide

# kubectl get nodes -o wide

# kubectl get all // will give port information

go to browser with an ip:30008

*****************************************

HPA:

---

apiVersion: apps/v1

kind: Deployment

metadata:

name: nginx

labels:

app: nginx

spec:

replicas: 1

selector:

matchLabels:

app: nginx

template:

metadata:

name: nginxpod

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx:latest

resources:

limits:

cpu: 10m

---

apiVersion: v1

kind: Service

metadata:

name: nginx-svc

spec:

type: ClusterIP ## this is default if we do not type in service definition

selector:

app: nginx

ports:

- protocol: TCP

port: 80

targetPort: 80

---

apiVersion: autoscaling/v1

kind: HorizontalPodAutoscaler

metadata:

name: nginx-hpa

spec:

scaleTargetRef:

apiVersion: apps/v1

kind: Deployment

name: nginx

minReplicas: 1

maxReplicas: 10

targetCPUUtilizationPercentage: 5

kubectl create -f hpa.yaml

Generate load:

kubectl run -i --tty load-generator --rm --image=busybox --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- http://serviceIP:portnumber; done"

******************************************

PV:

apiVersion: v1

kind: PersistentVolume

metadata:

name: block-pv

spec:

storageClassName: manual

capacity:

storage: 1Gi

accessModes:

- ReadWriteOnce

hostPath:

path: /tmp/data

kubectl create -f pv.yml

PVC

apiVersion: v1

kind: PersistentVolumeClaim

metadata:

name: pvc

spec:

storageClassName: manual

accessModes:

- ReadWriteOnce

resources:

requests:

storage: 1Gi

POD:

apiVersion: v1

kind: Pod

metadata:

name: pod-pvc

spec:

containers:

- image: nginx

name: c1

volumeMounts:

- mountPath: "/data"

name: my-volume

volumes:

- name: my-volume

persistentVolumeClaim:

claimName: pvc

refer: https://github.com/Sonal0409/DevOps_ClassNotes/tree/master/Kubernetese/PersistentVolume

********************************************

HELM

Helm install

curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3

chmod 700 get_helm.sh

./get_helm.sh

# Use GKE

helm repo add bitnami https://charts.bitnami.com/bitnami

helm install my-release bitnami/jenkins

helm list

#Wait for 2 mins to see Jenkins UP

kubectl get deploy

kubectl get pods

kubectl get svc

#check the NodePort and access the app with Node IP

**************************

# vim dev.properties

app.env:dev

app.mem=2048m

app.properties=dev.env.url

:wq!

# kubectl create configmap dev-config1 --from-file=dev.properties

# kubectl get configmap

# kubectl get configmap dev-config1 -o yaml

Use configmap for a pod

vim pod-configmap.yml

kind: Pod

apiVersion: v1

metadata:

name: pod-configmap

spec:

containers:

- image: nginx

name: c1

volumeMounts:

- name: config-volume

mountPath: /etc/config

volumes:

- name: config-volume

configMap:

name: dev-config1

restartPolicy: Never

:wq!

# kubectl apply -f pod-configmap.yml

# kubectl exec -it pod-configmap bash

# cd /etc/config

you will find the dev.properties file and configurations

Edit the configMAP

kubectl edit configmap -n <namespace> <configMapName> -o yaml

This opens up a vim editor with the configmap in yaml format. Now simply edit it and save it.

Refer the repo for more kubernetes concepts: https://github.com/Sonal0409/DevOps_ClassNotes/tree/master/Kubernetese