WordPress with Portworx on Kubernetes

This reference architecture document shows how you can deploy WordPress, an open-source content management system, with Portworx on Kubernetes. This architecture provides the following benefits:

• Portworx enables reliable and persistent storage to ensure WordPress runs with HA
• Portworx enables sharedv4 volumes for file uploads
• Kubernetes automatically replicates your MySQL data
• You can horizontally scale the WordPress container using multi-writer semantics for the file-uploads directory
• The cluster automatically repairs itself in the event of a node failure

Prerequisites

• You must have a Kubernetes cluster with a minimum of three worker nodes.
• Portworx is installed on your Kubernetes cluster. For details about how you can install Portworx on Kubernetes, see the Portworx on Kubernetes page.
• You must have Stork installed on your Kubernetes cluster. For details about how you can install Stork, see the Stork page.

Dynamically provision a volume for MySQL

1. Create a file called mysql-sc.yaml, specifying the following fields and values:

   • apiVersion: as storage.k8s.io/v1
   • kind: as StorageClass
   • metadata.name: with the name of your StorageClass object (this example uses mysql-sc)
   • provisioner: as kubernetes.io/portworx-volume. For details about the Portworx-specific parameters, refer to the Portworx Volume section of the Kubernetes website.
   • parameters.repl: with the number of replicas Portworx should create (this example creates two replicas)
   • parameters.priority_io: with the type of the storage pool (this example uses a high-priority storage pool)

     apiVersion: storage.k8s.io/v1
     kind: StorageClass
     metadata:
       name: mysql-sc
     provisioner: kubernetes.io/portworx-volume
     parameters:
       repl: "3"
       priority_io: "high"

   For more details about how you can configure a storage class, see the Using Dynamic Provisioning section of the Portworx documentation.

2. Apply the spec:

   kubectl apply -f mysql-sc.yaml

3. Create a file called mysql-pvc.yaml with the following content:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: mysql-pvc
     annotations:
       volume.beta.kubernetes.io/storage-class: mysql-sc
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 2Gi
   note

   This PVC references the mysql-sc storage class. As a result, Kubernetes will automatically create a new PVC for each replica.

4. Apply the spec:

   kubectl apply -f mysql-pvc.yaml

Dynamically provision a volume for WordPress

1. Create a file called wordpress-sc.yaml with the following content:

   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: wordpress-sc
   provisioner: kubernetes.io/portworx-volume
   parameters:
     repl: "3"
     priority_io: "high"
     shared: "true"
   note

   The sharedv4: "true" flag creates a globally shared namespace volume which can be used by multiple Pods.

2. Apply the spec:

   kubectl apply -f wordpress-sc.yaml

3. Create a file called wordpress-pvc.yaml with the following content:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: wp-pvc
     labels:
       app: wordpress
     annotations:
       volume.beta.kubernetes.io/storage-class: wordpress-sc
   spec:
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 1Gi
   note

   This PVC references the wordpress-sc storage class. As a result, Kubernetes will automatically create a new PVC for each replica.

4. Apply the spec:

   kubectl apply -f wordpress-pvc.yaml

Create a Kubernetes secret for storing your MySQL password

A secret is an object that contains sensitive data. To create a secret, you can use the kubectl create secret command. Note that, to protect your sensitive data, the kubectl get and kubectl describe commands do not display the content of a secret.

1. Use the echo command to save your MySQL password to a file called ./password.txt, replacing <YOUR-PASSWORD> with your actual password:

   echo -n '<YOUR-PASSWORD' > ./password.txt

2. To create a new secret, enter the kubectl create secret command, specifying:

• The generic parameter. This instructs Kubernetes to create a secret based on a file, directory, or specified literal value.

• The name of your secret (this example uses mysql-pass)

• The --from-file flag with the name of the file in which you stored your password

  kubectl create secret generic mysql-pass --from-file=./password.txt

3. Use the kubectl get secrets command to verify that Kubernetes created the secret:

   kubectl get secrets

Deploy MySQL

1. Create a file named mysql-service.yaml with the following content:

   apiVersion: v1
   kind: Service
   metadata:
     name: wordpress-mysql
     labels:
       app: wordpress
   spec:
     ports:
       - port: 3306
     selector:
       app: wordpress
       tier: mysql
     clusterIP: None

2. Apply the spec:

   kubectl apply -f mysql-service.yaml

3. Create a file named mysql-deployment.yaml with the following content:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: wordpress-mysql
     labels:
       app: wordpress
   spec:
     selector:
       matchLabels:
         app: wordpress
     strategy:
       type: Recreate
     template:
       metadata:
         labels:
           app: wordpress
           tier: mysql
       spec:
         # Use the Stork scheduler to enable more efficient placement of the pods
         schedulerName: stork
         containers:
         - image: mysql:5.6
           imagePullPolicy:
           name: mysql
           env:
             # $ kubectl create secret generic mysql-pass --from-file=password.txt
             # make sure password.txt does not have a trailing newline
           - name: MYSQL_ROOT_PASSWORD
             valueFrom:
               secretKeyRef:
                 name: mysql-pass
                 key: password.txt
           ports:
           - containerPort: 3306
             name: mysql
           volumeMounts:
           - name: mysql-persistent-storage
             mountPath: /var/lib/mysql
         volumes:
         - name: mysql-persistent-storage
           persistentVolumeClaim:
             claimName: mysql-pvc

   Note the following about this Deployment:

   • Kubernetes creates a single-instance MySQL database
   • Kubernetes creates an environment variable called MYSQL_ROOT_PASSWORD that contains your MySQL password
   • Portworx mounts the Portworx persistent volume in the /var/lib/mysql directory
   • The Stork scheduler will place your Pods closer to where their data is located

4. Apply the spec:

   kubectl apply -f mysql-deployment.yaml

Deploy WordPress

1. Create a file called wordpress-service.yaml with the following content:

   apiVersion: v1
   kind: Service
   metadata:
     name: wordpress
     labels:
       app: wordpress
   spec:
     ports:
       - port: 80
         nodePort: 30303
     selector:
       app: wordpress
       tier: frontend
     type: NodePort

   Note that the spec.type field is set to NodePort. Kubernetes exposes the service on each node and makes it accessible from outside the cluster. For more details, see the Type NodePort section of the Kubernetes documentation.

2. Apply the spec:

   kubectl apply -f wordpress-service.yaml

3. Create a file called wordpress-deployment.yaml with the following content:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: wordpress
     labels:
       app: wordpress
   spec:
     selector:
       matchLabels:
         app: wordpress
     replicas: 3
     strategy:
       type: Recreate
     template:
       metadata:
         labels:
           app: wordpress
           tier: frontend
       spec:
         # Use the Stork scheduler to enable more efficient placement of the pods
         schedulerName: stork
         containers:
         - image: wordpress:4.8-apache
           name: wordpress
           imagePullPolicy:
           env:
           - name: WORDPRESS_DB_HOST
             value: wordpress-mysql
           - name: WORDPRESS_DB_PASSWORD
             valueFrom:
               secretKeyRef:
                 name: mysql-pass
                 key: password.txt
           ports:
           - containerPort: 80
             name: wordpress
           volumeMounts:
           - name: wordpress-persistent-storage
             mountPath: /var/www/html
         volumes:
         - name: wordpress-persistent-storage
           persistentVolumeClaim:
             claimName: wp-pvc

   Note the following about this Deployment

   • Portworx will create three replicas of each volume
   • The Stork scheduler will place your Pods closer to where their data is located
   • Kubernetes will create an environment variable called WORDPRESS_DB_PASSWORD that contains your MySQL password

4. Apply the spec:

   kubectl apply -f wordpress-deployment.yaml

Validate the cluster functionality

1. List your Pods:

   kubectl get pods

2. Display your services:

   kubectl get services

Clean up

1. Enter the following command to delete the Kubernetes secret:

   kubectl delete secret mysql-pass

2. Use the kubectl delete to delete your WordPress deployment and PVC:

   kubectl delete -f wordpress-deployment.yaml
   kubectl delete -f wordpress-pvc.yaml

3. Use the kubectl delete to delete your MySQL deployment and PVC:

   kubectl delete -f mysql-deployment.yaml
   kubectl delete -f mysql-pvc.yaml

Discussion Forum

If you have more questions about this application, please head over to our discussion forum and feel free to ask more questions.