Deploy your first scaleable PHP/MySQL Web application in Kubernetes

In this article, I talk about how to deploy PHP/Mysql Web application on top of Kubernetes.

At the end of this article, you will get to know how to deploy PHP/Mysql Web application on top of Kubernetes. In my previous article, I talk about how to use docker to deploy a PHP application.

https://www.dhirubhai.net/pulse/docker-php-developers-raghav-agarwal/

Prerequisite

• Having Knowledge of containerization tools like Docker, Podman, cri-o.
• Kubernetes cluster ( Single Node will also be okay).

Background

Docker is a great tool when you have to divide your application into multiple components or we can say that for each program/service of your application you need a different operating system for security as well as for ease of managing and running them as a single app. Here program/service you can consider for an example as PHP, Mysql. So far it is good but what in case of if your application is running on top on docker container and that container might be terminated or in case of traffic increases how you manage the loads? or how you update the application if version2 of your app comes with having zero downtime? Here the roles of Kubernetes comes in play. Kubernetes will take care of all things from scaling to distributing traffic, orchestation, rolling updates of containers.

So this is the reason we used the Kubernetes tool for orchestrating the containers. Other tools are also available for orchestrating the containers.

• Docker Swarm
• Apache Mesos

Creating PVC for both PHP and Mysql

Mysql and PHP each require a PresistentVolume to store data. Because as any of pods goes down the data present inside the pod will also be lost. So for this is require a Persistent volume claim (PVC).

Many Cluster environments have a default storage class installed. When the storage class is not specified in the PresistentVolume Claim, the cluster default storage class is used instead.

When a PresistentVolumeClaim is created, a PresistentVolume is dynamically provisioned based on the storage class configuration.

Creating a PVC resources

1. Mysql

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: db-pvc
  labels:
    name: dbpvc1
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi

• Create PVC from Kubectl Command

kubectl create -f <file_name.yml>

• For Confirmation:

kubectl get pvc db-pvc

2. For PHP

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: frontend-pvc
  labels:
    name: frontendpvc1
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi

• Create PVC from Kubectl Command

kubectl create -f <file_name.yml>

• For Confirmation:

kubectl get pvc frontend-pvc

Creating Deployment for both PHP and Mysql

In Kubernetes deployment is a resource object in Kubernetes that provides declarative updates to applications. A deployment allows you to describe an application's lifecycle such as which image to use, the no of pods there should be, and the way in which they should be updated

Creating Deployment Resource for

1. Database

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mydb-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      env: production-db
  template:
    metadata:
      name: mydb-pod
      labels:
        env: production-db
    spec:
      volumes:
        - name: db-vol
          persistentVolumeClaim:
            claimName: db-pvc
      containers:
      - name: database
        image: ragh19/phpproject:mysql_v1
        volumeMounts:
          - mountPath: /var/lib/mysql
            name: db-vol

Here we are using a public image for MySQL present on Docker Hub tagged as ragh19/phpproject:mysql_v1.

• Create Deployment from Kubectl Command

kubectl create -f <file_name.yml>

• For Confirmation:

kubectl get deployment mydb-deployment

2. PHP

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myphp-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      env: production-frontend
  template:
    metadata:
      name: myfrontend-pod
      labels:
        env: production-frontend
    spec:
      volumes:
        - name: front-vol
          persistentVolumeClaim:
            claimName: frontend-pvc
      containers:
      - name: frontend
        image: ragh19/phpproject:web_v1
        volumeMounts:
          - mountPath: /var/www/html
            name: front-vol

Here we are using a public image for MySQL present on Docker Hub tagged as ragh19/phpproject:web_v1.

• Create Deployment from Kubectl Command

kubectl create -f <file_name.yml>

• For Confirmation:

kubectl get deployment myphp-deployment

Creating Service for both PHP and Mysql

A service on Kubernetes is an abstraction that defines a logical set of pods and policies by which to access them. In Kubernetes services is of 3 types depending on the use-case which service you want to use.

1. ClusterIP
2. NodePort
3. LoadBalancer

I am not going into deep dive which service should be used, Every service has different use-case. In my case, I am using NodePort as a service that exposed your application to the outside world having NodePort.

Creating Service Resource for

1. Database

apiVersion: v1
kind: Service
metadata:
  name: mydb-service
spec:
  type: NodePort
  ports:
    - targetPort: 3306
      port: 3306
      nodePort: 30008
  selector:
    env: production-db

Here Database service is exposed to 30008 port no. You can access this database service by IP and Port No having database username as root and password is redhat.

• Create Service from Kubectl Command

kubectl create -f <file_name.yml>

• For Confirmation:

kubectl get svc mydb-service

2. For PHP

apiVersion: v1
kind: Service
metadata:
  name: myphp-service
spec:
  type: NodePort
  ports:
    - targetPort: 80
      port: 80
      nodePort: 30009
  selector:
    env: production-frontend

Here PHP service is exposed to 30009 port no. You can access PHP application by IP and port no in the browser.

Creating sample index.php file for testing connectivity between PHP application and database.

<?php
$conn = new mysqli("mydb-service", "root", "redhat", "mydb");
// Check connection
if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
}




$sql = "SELECT name FROM user";
$result = $conn->query($sql);




if ($result->num_rows > 0) {
        // output data of each row
        while($row = $result->fetch_assoc()) {
                echo $row['name']."<br>";
        }
} else {
        echo "0 results";
}
$conn->close();

Instead of using the IP of pod in the arguments of mysqli. I am using a database service name mydb-service for connectivity.

Conclusion

So in this article, we see how to deploy your first web application on top of Kubernetes. We just touch the surface of Kubernetes. Many more features like ingress, RollingUpdates, Storageclass are also being used. Following up on this post, I need a guy who can help in the understanding of ingress, How can we use ingress in AWS?

• Future Implenatations:

How to used Ingress for same php-mysql application and having CI/CD to show the power of rolling updates.

Code is available on GitHub

Yo