How does Kubernetes simplify containerized application deployment process

Question

Could somebody illustrate with an example how kubernetes simplifies the process of containerized application deployment.

Answer 1

A application deployment requires , web tier , application tier and database tier . All these requirements will spawn multiple containers and these containers should communicate among each other . Kubernetes cluster will take care of the whole system and orchestrates the container needs . 

Let us look at a quick WordPress application example. 

WordPress application consists of frontend(WordPress running on PHP and Apache) and backend(MySQL). 

The below YAML file can help you specify everything you will need to bring WordPress Application in a single shot:

apiVersion: v1
kind: Service
metadata:
 name: wordpress
 labels:
   app: wordpress
spec:
 ports:
   - port: 80
 selector:
   app: wordpress
   tier: frontend
 type: LoadBalancer
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
 name: wp-pv-claim
 labels:
   app: wordpress
spec:
 storageClassName: manual
 accessModes:
   - ReadWriteOnce
 resources:
   requests:
     storage: 2Gi
---
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
 name: wordpress
 labels:
   app: wordpress
spec:
 storageClassName: manual
 selector:
   matchLabels:
     app: wordpress
     tier: frontend
 strategy:
   type: Recreate
 template:
   metadata:
     labels:
       app: wordpress
       tier: frontend
   spec:
     containers:

 - image: wordpress:4.8-apache
       name: wordpress
       env:
       - name: WORDPRESS_DB_HOST
         value: wordpress-mysql
       - name: WORDPRESS_DB_PASSWORD
         valueFrom:
           secretKeyRef:
             name: mysql-pass
             key: password
       ports:
       - containerPort: 80
         name: wordpress
       volumeMounts:
       - name: wordpress-persistent-storage
         mountPath: /var/www/html
     volumes:
     - name: wordpress-persistent-storage
       persistentVolumeClaim:
         claimName: wp-pv-clai

I assume that you have n-node Kubernetes cluster running in your infrastructure. All you need is to run the below command:

kubectl create -f wordpress-deployment.yaml   

That’s it.

Browse to http://<IP>:80 port to open to see WordPress App up and running. Hence, we saw that how Kubernetes simplifies the application deployment.