Example: Deploying WordPress and MySQL with Persistent Volumes

    A PersistentVolume (PV) is a piece of storage in the cluster that has been manually provisioned by an administrator, or dynamically provisioned by Kubernetes using a . A PersistentVolumeClaim (PVC) is a request for storage by a user that can be fulfilled by a PV. PersistentVolumes and PersistentVolumeClaims are independent from Pod lifecycles and preserve data through restarting, rescheduling, and even deleting Pods.

    Warning: This deployment is not suitable for production use cases, as it uses single instance WordPress and MySQL Pods. Consider using to deploy WordPress in production.

    Note: The files provided in this tutorial are using GA Deployment APIs and are specific to kubernetes version 1.9 and later. If you wish to use this tutorial with an earlier version of Kubernetes, please update the API version appropriately, or reference earlier versions of this tutorial.

    • Create PersistentVolumeClaims and PersistentVolumes
    • Create a with
      • a Secret generator
      • MySQL resource configs
      • WordPress resource configs
    • Apply the kustomization directory by kubectl apply -k ./
    • Clean up

    Before you begin

    You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

    To check the version, enter kubectl version.

    The example shown on this page works with kubectl 1.14 and above.

    Download the following configuration files:

    2. wordpress-deployment.yaml

    MySQL and Wordpress each require a PersistentVolume to store data. Their PersistentVolumeClaims will be created at the deployment step.

    Many cluster environments have a default StorageClass installed. When a StorageClass is not specified in the PersistentVolumeClaim, the cluster’s default StorageClass is used instead.

    When a PersistentVolumeClaim is created, a PersistentVolume is dynamically provisioned based on the StorageClass configuration.

    Warning: In local clusters, the default StorageClass uses the hostPath provisioner. hostPath volumes are only suitable for development and testing. With hostPath volumes, your data lives in /tmp on the node the Pod is scheduled onto and does not move between nodes. If a Pod dies and gets scheduled to another node in the cluster, or the node is rebooted, the data is lost.

    Note: If you are bringing up a cluster that needs to use the hostPath provisioner, the --enable-hostpath-provisioner flag must be set in the controller-manager component.

    Create a kustomization.yaml

    A Secret is an object that stores a piece of sensitive data like a password or key. Since 1.14, kubectl supports the management of Kubernetes objects using a kustomization file. You can create a Secret by generators in kustomization.yaml.

    Add a Secret generator in kustomization.yaml from the following command. You will need to replace YOUR_PASSWORD with the password you want to use.

    The following manifest describes a single-instance MySQL Deployment. The MySQL container mounts the PersistentVolume at /var/lib/mysql. The MYSQL_ROOT_PASSWORD environment variable sets the database password from the Secret.

    application/wordpress/mysql-deployment.yaml 

    1. apiVersion: v1
    2. kind: Service
    3. metadata:
    4.   name: wordpress-mysql
    5.   labels:
    6.     app: wordpress
    7. spec:
    8.   ports:
    9.     - port: 3306
    10.   selector:
    11.     app: wordpress
    12.     tier: mysql
    13.   clusterIP: None
    14. ---
    15. apiVersion: v1
    16. kind: PersistentVolumeClaim
    17. metadata:
    18.   name: mysql-pv-claim
    19.   labels:
    20.     app: wordpress
    21. spec:
    22.   accessModes:
    23.     - ReadWriteOnce
    24.   resources:
    25.     requests:
    26.       storage: 20Gi
    27. ---
    28. apiVersion: apps/v1
    29. kind: Deployment
    30. metadata:
    31.   name: wordpress-mysql
    32.   labels:
    33.     app: wordpress
    34. spec:
    35.   selector:
    36.     matchLabels:
    37.       app: wordpress
    38.       tier: mysql
    39.   strategy:
    40.     type: Recreate
    41.   template:
    43.         app: wordpress
    44.         tier: mysql
    45.     spec:
    46.       containers:
    47.       - image: mysql:5.6
    48.         name: mysql
    49.         env:
    50.         - name: MYSQL_ROOT_PASSWORD
    51.           valueFrom:
    52.             secretKeyRef:
    53.               name: mysql-pass
    54.               key: password
    55.         ports:
    56.         - containerPort: 3306
    57.           name: mysql
    58.         volumeMounts:
    59.         - name: mysql-persistent-storage
    60.           mountPath: /var/lib/mysql
    61.       volumes:
    62.       - name: mysql-persistent-storage
    63.         persistentVolumeClaim:
    64.           claimName: mysql-pv-claim

    The following manifest describes a single-instance WordPress Deployment. The WordPress container mounts the PersistentVolume at /var/www/html for website data files. The WORDPRESS_DB_HOST environment variable sets the name of the MySQL Service defined above, and WordPress will access the database by Service. The WORDPRESS_DB_PASSWORD environment variable sets the database password from the Secret kustomize generated.

    Example: Deploying WordPress and MySQL with Persistent Volumes - 图2

    1. apiVersion: v1
    2. kind: Service
    3. metadata:
    4.   name: wordpress
    5.   labels:
    6.     app: wordpress
    7. spec:
    8.   ports:
    9.     - port: 80
    10.   selector:
    11.     app: wordpress
    12.     tier: frontend
    13.   type: LoadBalancer
    14. ---
    15. apiVersion: v1
    16. kind: PersistentVolumeClaim
    17. metadata:
    18.   name: wp-pv-claim
    19.   labels:
    20.     app: wordpress
    21. spec:
    22.   accessModes:
    23.     - ReadWriteOnce
    24.   resources:
    25.     requests:
    26.       storage: 20Gi
    27. ---
    28. apiVersion: apps/v1
    29. kind: Deployment
    30. metadata:
    31.   name: wordpress
    32.   labels:
    34. spec:
    35.   selector:
    36.     matchLabels:
    37.       app: wordpress
    38.       tier: frontend
    39.     type: Recreate
    40.   template:
    41.     metadata:
    42.       labels:
    43.         app: wordpress
    44.         tier: frontend
    45.     spec:
    46.       containers:
    47.       - image: wordpress:4.8-apache
    48.         name: wordpress
    49.         env:
    50.         - name: WORDPRESS_DB_HOST
    51.           value: wordpress-mysql
    52.         - name: WORDPRESS_DB_PASSWORD
    53.           valueFrom:
    54.             secretKeyRef:
    55.               name: mysql-pass
    56.               key: password
    57.         ports:
    58.         - containerPort: 80
    59.           name: wordpress
    60.         volumeMounts:
    61.         - name: wordpress-persistent-storage
    62.           mountPath: /var/www/html
    63.       volumes:
    64.       - name: wordpress-persistent-storage
    65.         persistentVolumeClaim:
    66.           claimName: wp-pv-claim

    1. Download the MySQL deployment configuration file.

      1. curl -LO https://k8s.io/examples/application/wordpress/mysql-deployment.yaml

    2. Download the WordPress configuration file.

      1. curl -LO https://k8s.io/examples/application/wordpress/wordpress-deployment.yaml

    3. Add them to kustomization.yaml file.

      1. cat <<EOF >>./kustomization.yaml
      2. resources:
      3.   - mysql-deployment.yaml
      4.   - wordpress-deployment.yaml
      5. EOF

    Apply and Verify

    The kustomization.yaml contains all the resources for deploying a WordPress site and a MySQL database. You can apply the directory by

    Now you can verify that all objects exist.

    1. Verify that the Secret exists by running the following command:

      1. kubectl get secrets

      The response should be like this:

      1. NAME                    TYPE                                  DATA   AGE
      2. mysql-pass-c57bb4t7mf   Opaque                                1      9s

    2. Verify that a PersistentVolume got dynamically provisioned.

      1. kubectl get pvc

      The response should be like this:

      1. NAME             STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS       AGE
      2. mysql-pv-claim   Bound     pvc-8cbd7b2e-4044-11e9-b2bb-42010a800002   20Gi       RWO            standard           77s
      3. wp-pv-claim      Bound     pvc-8cd0df54-4044-11e9-b2bb-42010a800002   20Gi       RWO            standard           77s

    3. Verify that the Pod is running by running the following command:

      1. kubectl get pods

      Note: It can take up to a few minutes for the Pod’s Status to be RUNNING.

      The response should be like this:

    4. Verify that the Service is running by running the following command:

      1. kubectl get services wordpress

      The response should be like this:

      1. NAME        TYPE            CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
      2. wordpress   LoadBalancer    10.0.0.89    <pending>     80:32406/TCP   4m

      Note: Minikube can only expose Services through NodePort. The EXTERNAL-IP is always pending.

    5. Run the following command to get the IP Address for the WordPress Service:

      1. minikube service wordpress --url

      The response should be like this:

    6. Copy the IP address, and load the page in your browser to view your site.

      You should see the WordPress set up page similar to the following screenshot.

      Warning: Do not leave your WordPress installation on this page. If another user finds it, they can set up a website on your instance and use it to serve malicious content.

      Either install WordPress by creating a username and password or delete your instance.

      1. kubectl delete -k ./

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