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WordPress in Docker. Part 3: Docker and Kubernetes

WordPress in Docker. Part 3: Docker and Kubernetes

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Buddy.Works
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6 min read

This guide covers creating K8s volumes and configuring a WP instance with a MySQL database in a most simple way — a perfect introduction to Kubernetes and Docker for newbies.

This article is a direct followup to the articles on dockerizing WordPress and automating WordPress delivery, allowing you to introduce the power of Docker to your dev setup. If you already have a running K8s application, check out this guide to learn how to automate your K8s deployments.

Configure a PersistentVolume in the K8s cluster

In this example, we’ll use a hostPath volume since we only have one node in the cluster. This type of volume mounts the path from the node's filesystem into K8s.

The hostPath volume is not recommended for multi-node production clusters. If you're working on multiple nodes, follow the instructions here.

Create volumes.yml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv-1
  labels:
    type: local
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /k8/volume/pv-1
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv-2
  labels:
    type: local
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /k8/volume/pv-2

This config will create two R/W 10GB volumes in the node paths:

/k8/volume/pv-1
/k8/volume/pv-2

Create your K8s volumes

To create the volumes, run

$ kubectl apply -f volumes.yml

You can check if everything’s working correctly by running

$ kubectl get pv

NAME       CAPACITY ACCESSMODES RECLAIMPOLICY STATUS CLAIM STORAGECLASS REASON AGE
local-pv-1 10Gi     RWO         Retain        Available                        13s
local-pv-2 10Gi     RWO         Retain        Available                        13s

Configure a MySQL database

Start with creating a secret password for the MySQL root user:

$ kubectl create secret generic mysql-pass --from-literal=password=ROOT_PASSWORD

You can check if the password was properly configured by running.

$ kubectl get secrets

NAME       TYPE   DATA AGE
mysql-pass Opaque 1    17h

Secrets in K8s are hidden and cannot be displayed. This means there’s no risk of exposing them in config files in public repositories.

Create mysql.yml

The file below will create a single MySQL instance with a proper volume and port mapping. It also uses the secret that we created earlier:

apiVersion: v1
kind: Service
metadata:
  name: wordpress-mysql
  labels:
    app: wordpress
spec:
  ports:
    - port: 3306
  selector:
    app: wordpress
    tier: mysql
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: wordpress-mysql
  labels:
    app: wordpress
spec:
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: wordpress
        tier: mysql
    spec:
      containers:
      - image: mysql:5.6
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-pass
              key: password
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pv-claim

TableMain of mysql.yml

The file consists of 3 separate configs:

  • Service — maps MySQL’s port 3306 and makes it available for all containers with labels app:wordpress & tier:mysql

  • Persistent volume claim — declares claim on the volume that will be used in the MySQL container configuration

  • Deployment — declares the creation strategy and specs of our MySQL container:

    TableMain of the MySQL container:

    • it’s an image from the Docker Hub: mysql:5.6
    • it has app:wordpress & tier:frontend labels (used in Service)
    • it contains an environment variable called MYSQL_ROOT_PASSWORD which holds the value from our secret password
    • it has an open port 3306
    • it has a volume claim mounted in /var/lib/mysql

Create your MySQL instance on K8s

To create the database, run

``bash kubectl apply -f mysql.yml ```

You can check the progress of deployment by running

kubectl get pods

Once you see status:Running, the MySQL service is ready for action.

Deploy WordPress to Kubernetes

Begin with downloading WordPress sources from https://wordpress.org/download/.

Configure the Docker file

Now we need to dockerize the WordPress instance. The Docker file only requires WP sources:

FROM wordpress:php7.1-apache
COPY . /usr/src/wordpress/

Build & push the Docker image

The next step is building the Docker image and pushing it to your Docker registry:

$ docker login
$ docker build -t buddy/wordpress .
$ docker push buddy/wordpress

Create wordpress.yml

To deploy WordPress on a Kubernetes node you need to create a proper config file:

apiVersion: v1
kind: Service
metadata:
  name: wordpress
  labels:
    app: wordpress
spec:
  ports:
    - port: 80
      nodePort: 30000
  selector:
    app: wordpress
    tier: frontend
  type: NodePort
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: wp-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: wordpress
  labels:
    app: wordpress
spec:
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: wordpress
        tier: frontend
    spec:
      containers:
      - image: buddy/wordpress:latest
        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-claim

TableMain of wordpress.yml

The file consists of 3 separate configs:

  • Service — maps port 80 of the container to the node’s external IP:30000 for all containers with labels app:wordpress & tier:frontend

  • Persistent volume claim — declares claim on the volume that will be used in the WP container configuration

  • Deployment — declares the creation strategy and spec of our WordPress container:

    TableMain of the WP container:

    • it’s an image from the Docker Hub: buddy/wordpress:latest
    • it has app:wordpress & tier:frontend labels (used in Service)
    • it contains environment variables WORDPRESS_DB_HOST, which is the internal host name of the MySQL instance, and WORDPRESS_DB_PASSWORD, which holds the value from our secret password
    • it has an open port 80
    • it has a volume claim mounted in /var/www/html from which the WP sources are served

Create your WP instance on K8s

To deploy your WP instance, run

kubectl apply -f wordpress.yml

You can check the progress of deployment by running

kubectl get pods

Once you see status:Running, the WordPress service is ready for action.

Congratulations! You have successfully deployed your WordPress project to Kubernetes. You can visit the site by going to node IP:30000.

Advantages & Extenstions

Running WordPress and other web projects on Kubernetes gives you a series of benefits:

  • easy configuration in just a few files

  • you can recreate the whole configuration on any host with a couple of commands:

$ kubectl apply -f volumes.yml
$ kubectl create secret generic mysql-pass --from-literal=password=ROOT_PASSWORD
$ kubectl apply -f mysql.yml
$ kubectl apply -f wordpress.yml

  • you can extend the configuration by using volumes on AWS or other production-ready volumes

  • you can change the external port mapping for proper load balancing

  • you can change the deployment strategy from Recreate to RollingUpdate to increase container counts and ensure no downtime during the deployment

Automate Kubernets delivery with Buddy

With Buddy, you can streamline the whole K8s deployment down to a single push to branch: from building the Docker image, to applying config changes, to updating the image on your Kubernetes cluster. Check out the guide to see how it looks in action!

You can also automate deployment of any other popular language or framework. Just let us know what you do on the live-chat or drop a line support@buddy.works and we’ll create a delivery pipeline for your project free of charge!

Kubernetesk8sWeb DevelopmentDevopsWordPress