kubernets创建有状态集合，未启动Pod

Question

我创建了一个有状态的集合，但是在运行了kubectl apply -f wordpress-database.yaml和kubectl get statefulset之后，我看到pod的状态始终为零（为什么？）：

wordpress-database   0/1     25m

yaml（请不要考虑对齐）

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: wordpress-database
spec:
  selector:
    matchLabels:
      app: blog
  serviceName: "blog"
  replicas: 1
  template:
  metadata:
  labels:
    app: blog 
  spec:
  containers:
  - name: database
    image: mysql:5.7
    ports:
    - containerPort: 3306
    env:
    - name: MYSQL_ROOT_PASSWORD
      value: rootPassword
    - name: MYSQL_DATABASE
      value: database
    - name: MYSQL_USER
      value: user
    - name: MYSQL_PASSWORD
      value: password          
    volumeMounts:
    - name: data
      mountPath: /var/lib/mysql
  - name: blog
    image: wordpress:latest
    ports:
    - containerPort: 80
    env:
    - name: WORDPRESS_DB_HOST
      value: 127.0.0.1:3306
    - name: WORDPRESS_DB_NAME
      value: database
    - name: WORDPRESS_DB_USER
      value: user
    - name: WORDPRESS_DB_PASSWORD
      value: password  
    volumeClaimTemplates:
    - metadata:
    name: data
    spec:
    resources:
    requests:
      storage: 1Gi