本文由 简悦 SimpRead 转码， 原文地址 kubernetes.io

This tutorial shows you how to deploy a WordPress site and a MySQL database using Minikube. Both appl……

This tutorial shows you how to deploy a WordPress site and a MySQL database using Minikube. Both applications use PersistentVolumes and PersistentVolumeClaims to store data.

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 StorageClass. 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 WordPress Helm Chart 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.

Objectives

Create PersistentVolumeClaims and PersistentVolumes

  • Create a kustomization.yaml 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:

  1. mysql-deployment.yaml

  2. wordpress-deployment.yaml

Create PersistentVolumeClaims and PersistentVolumes 创建PV和PVC

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

mysql和wordpress都需要PV来存储数据。他们的PVC会在部署阶段创建

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.

许多集群都有默认安装的storageClass。当PVC中未指明StorageClass时，系统会使用默认的StorageClass

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

当PVC被创建后，PV会基于StorageClass的配置信息进行动态供给。

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.

警告：
在本地集群中，默认的storageclass使用hostPath供应商。hostPath存储卷只适合研发和测试使用。使用hostPath存储卷时，你的数据会存储在tmp节点上

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.

注意：
如果你启动了一个需要使用hostPath供应商的集群，则必须在controller-manager组件中定义—enable-hostpath-provisioner`

Note: If you have a Kubernetes cluster running on Google Kubernetes Engine, please follow this guide.

Create a kustomization.yaml

Add a Secret generator

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.

  1. cat <<EOF >./kustomization.yaml
  2. secretGenerator:
  3. - name: mysql-pass
  4.   literals:
  5.   - password=YOUR_PASSWORD
  6. EOF

Add resource configs for MySQL and WordPress

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.

以下清单描述了单个

apiVersion: v1
kind: Service
metadata:
  name: wordpress-mysql
  labels:
    app: wordpress
spec:
  ports:
    - port: 3306
  selector:
    app: wordpress
    tier: mysql
  clusterIP: None
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
  labels:
    app: wordpress
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: wordpress-mysql
  labels:
    app: wordpress
spec:
  selector:
    matchLabels:
      app: wordpress
      tier: mysql
  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

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.

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:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: wordpress
  labels:
    app: wordpress
spec:
  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-claim
  1. Download the MySQL deployment configuration file.
    curl -LO https://k8s.io/examples/application/wordpress/mysql-deployment.yaml
  1. Download the WordPress configuration file.
    curl -LO https://k8s.io/examples/application/wordpress/wordpress-deployment.yaml
  1. Add them to kustomization.yaml file.
cat <<EOF >>./kustomization.yaml
resources:
  - mysql-deployment.yaml
  - wordpress-deployment.yaml
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:
    The response should be like this:
    NAME                    TYPE                                  DATA   AGE
mysql-pass-c57bb4t7mf   Opaque                                1      9s
  1. Verify that a PersistentVolume got dynamically provisioned.

    Note: It can take up to a few minutes for the PVs to be provisioned and bound.


The response should be like this:

NAME             STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS       AGE
mysql-pv-claim   Bound     pvc-8cbd7b2e-4044-11e9-b2bb-42010a800002   20Gi       RWO            standard           77s
wp-pv-claim      Bound     pvc-8cd0df54-4044-11e9-b2bb-42010a800002   20Gi       RWO            standard           77s
  1. Verify that the Pod is running by running the following command:

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


The response should be like this:

NAME                               READY     STATUS    RESTARTS   AGE
wordpress-mysql-1894417608-x5dzt   1/1       Running   0          40s
  1. Verify that the Service is running by running the following command:
    kubectl get services wordpress


The response should be like this:

NAME        TYPE            CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
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.

  1. Run the following command to get the IP Address for the WordPress Service:
    minikube service wordpress --url


The response should be like this:

http://1.2.3.4:32406
  1. 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.
    Example： Deploying WordPress and MySQL with Persistent Volumes - 图1

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.

Cleaning up

  1. Run the following command to delete your Secret, Deployments, Services and PersistentVolumeClaims:

What’s next