Kubernetes 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 another Jenkins pod:

# vim pod-definition2.yml

i

---

apiVersion: v1

kind: Pod

metadata:

name: jenkins-pod

labels:

author: edureka

type: CI-CD

spec:

containers:

- name: myjenkins

image: jenkins

# kubectl get pods

#kubectl get pods -o wide

# 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

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

Deployment: ROLLING UPDATE

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Highlevel kubernetes object called Deployment:

For this we use an object called Deployment Object

Create a new yaml file

# vim deployment.yml

i

apiVersion: apps/v1

kind: Deployment

metadata:

name: nginx-deployment

labels:

author: edureka

type: proxyserver

spec:

replicas: 2

selector:

matchLabels:

type: proxyserver

template:

metadata:

name: nginx-pod

labels:

type: proxyserver

spec:

containers:

- name: mynginx

image: nginx:1.7.9

ports:

- containerPort: 80

hostPort: 8888

# kubectl get all

//will show deployment created.

# kubectl get pods

// will show all 3 pods created

# kubectl get deployment

// will show deployment which we just created information

Lets do rolling update now:

# kubectl get all

# kubectl --record deployment.apps/nginx-deployment set image deployment.v1.apps/nginx-deployment mynginx=nginx:1.9.1

# kubectl get pods

will give all pods, here you will see a duplicate rpelica is created for which evrsion is being updated and after which it will delete the earlier version replica. so users will not face any downtime

here copy the name of pod only begining : nginx-deployment

# kubectl describe pods nginx-deployment | less

Clean Up

# kubectl delete -f deployment.yml

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

Creation of SERVICE OBJECTS

NODEPORT:

Create a jenkins pod definition file

# vim pod-definition3.yml

---

apiVersion: v1

kind: Pod

metadata:

name: jenkins-pod1

labels:

author: edureka

type: CI

spec:

containers:

- name: myjenkins1

image: jenkins

:wq!

# kubcectl create -f pod-definition3.yml

# kubectl get pods

# kubectl get pods -o wide

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

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:

author: edureka

type: CI-CD

# 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

# kubectl delete -f myservice.yml

# kubectl delete -f pod-definition3.yml

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

Service Object: LoadBalancer

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

Create a new deployment definition file for nginx pod

# vim deployment.yml

i

---

apiVersion: apps/v1

kind: Deployment

metadata:

name: nginx-deployment

labels:

author: edureka

type: proxyserver

spec:

replicas: 2

selector:

matchLabels:

type: proxyserver

template:

metadata:

name: nginx-pod

labels:

type: proxyserver

spec:

containers:

- name: mynginx

image: nginx:1.7.9

ports:

- containerPort: 80

hostPort: 8888

# kubectl get pods

# kubectl get pods -o wide

# kubectl get nodes -o wide

We will create a new definition file of kind Service object and type as LoadBalancer,

here take the label same as that of pod given in above deployment under template:

metadata:

name: nginx-pod

labels:

type: proxyserver -- take this label information

# vim myservice2.yml

i

---

apiVersion: v1

kind: Service

metadata:

name: nginx-myservice

labels:

type: proxy1

spec:

type: LoadBalancer

ports:

- port: 80

targetPort: 80

selector:

type: proxyserver

# kubectl create -f myservice2.yml

# kubectl get all

// you will see a service with name as service/nginx-myservice

and external ip address as pending

re execute the command to see if external ip is generated

OR

# kubectl describe service/nginx-myservice | less

OR

# kubectl describe service nginx-myservice | less

These all commands will give complete information about service and we can find the load balancer ingress ip

Clean up

# kubectl delete -f myservice2.yml

# kubectl get all

# kubectl delete -f deployment2.yml

# kubectl get pods

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