本文以 WordPress 为例，演示在 Kubernetes 集群中运行有状态服务，以及相关命令和概念。
为 MYSQL 密码创建 Secret
Secret 是一个对象，存储一系列的敏感信息，比如 password 和 key。
创建 Secret 对象
kubectl create secret generic mysql-pass --from-literal=password=YOUR-PASSWORD
YOUR-PASSWORD 替换为你想实际应用的密码
查看 Secrets
kubectl get secrets
NAME TYPE DATA AGE
default-token-jdn58 kubernetes.io/service-account-token 3 1d
mysql-pass Opaque 1 6s
部署 MySQL
在 k8s 中，PersistentVolumeClaims（简称 PVC） 和 PersistentVolumes（简称PV） 用于数据的持久化存储。
- PV：持久化卷，是集群的一部分。就像 Node 一样，属于集群中的资源。
- PVC：用户对存储的请求。它与 Pod 相似，Pod 消耗 Node 资源，PVC 消耗 PV 资源。
1、新建 MySQL 部署文件 mysql-deployment.yaml
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: 10Gi
---
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
2、部署 MySQL
kubectl create -f mysql-deployment.yaml
3、确认 PersistentVolume 是动态配置的
kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
mysql-pv-claim Bound pvc-22264d66-543c-11e8-993e-080027736407 10Gi RWO standard 1m
4、确认 Pod 正常运行
kubectl get pod
NAME READY STATUS RESTARTS AGE
wordpress-mysql-7ddd5d59dd-njv2b 1/1 Running 0 5m
部署 WordPress
和 MySQL 类似，WordPress 也需要创建 Deployment 和 Service ，也需要 PVC 做持久化存储、Secret 做密码保密，另外，WordPress 需要暴露给集群外部的流量使用，还需要配置 type: NodePort。
1、创建 WordPress 部署文件 wordpress-deployment.yaml
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: 10Gi
---
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: registry.docker-cn.com/library/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
2、部署 WordPress
kubectl create -f wordpress-deployment.yaml
3、稍作等待，查看整个 WordPress 服务，可以看到 MySQL 和 WordPress 均正常工作
NAME READY STATUS RESTARTS AGE
pod/wordpress-5d7d6dfb58-mxr9k 1/1 Running 0 4m
pod/wordpress-mysql-7ddd5d59dd-njv2b 1/1 Running 0 24m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 1d
service/wordpress LoadBalancer 10.107.47.102 <pending> 80:30435/TCP 4m
service/wordpress-mysql ClusterIP None <none> 3306/TCP 24m
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
deployment.apps/wordpress 1 1 1 1 4m
deployment.apps/wordpress-mysql 1 1 1 1 24m
NAME DESIRED CURRENT READY AGE
replicaset.apps/wordpress-5d7d6dfb58 1 1 1 4m
replicaset.apps/wordpress-mysql-7ddd5d59dd 1 1 1 24m
提醒： Minikube 只能通过 NodePort 暴露服务. EXTERNAL-IP 永远是 <pending>.
4、访问 WordPress
minikube service wordpress
移除 WordPress
删除 Secret
kubectl delete secret mysql-pass
删除 Deployment
kubectl delete deployment -l app=wordpress
删除 Service
kubectl delete service -l app=wordpress
删除 PVC
kubectl delete pvc -l app=wordpress
-l, --selector='': 选择器过滤, 不包含那些未初始化的.
