使用Kubernetes创建PHP留言板系统

本文将演示使用kubernetes系统基于 kubeguide相关的镜像文件创建基于php和redis的留言板系统，因为系统资源有限，kubernetes集群只有一个master节点和slave节点。
Docker本地仓库与kubernetes集群配置请查看前文。

一、环境介绍
操作系统版本：centos linux 7.2 64bit
Master节点：192.168.115.5/24 vm1
Slave节点1：192.168.115.6/24 vm2

访问流程图如下：

二、在线下载相关的镜像文件，并纳入本地仓库统一管理

# docker pull kubeguide/redis-master
# docker pull kubeguide/guestbook-php-frontend
# docker pull kubeguide/guestbook-redis-slave
# docker tag kubeguide/redis-master registry.fjhb.cn/redis-master
# docker tag kubeguide/guestbook-php-frontend registry.fjhb.cn/guestbook-php-frontend
# docker tag kubeguide/guestbook-redis-slave registry.fjhb.cn/guestbook-redis-slave 
# docker push registry.fjhb.cn/redis-master
# docker push registry.fjhb.cn/guestbook-php-frontend
# docker push registry.fjhb.cn/guestbook-redis-slave 
# curl -u yang:123 -XGET https://registry.fjhb.cn/v2/_catalog 
# docker images |grep fjhb

三、配置文件准备
1、创建redis-master rc和service配置文件

# cat redis-master-controller.yaml 
apiVersion: v1
kind: ReplicationController
metadata:
  name: redis-master
spec:
  replicas: 1
  selector:
    name: redis-master
  template:
    metadata:
      name: redis-master
      labels:
        name: redis-master
    spec:
      containers:
      - name: redis-master
        image: registry.fjhb.cn/redis-master
        ports:
        - containerPort: 6379

# cat redis-master-service.yaml 
apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    name: redis-master
spec:
  ports:
  - port: 6379
    targetPort: 6379
  selector:
name: redis-master

2、创建redis-slave的rc和service配置文件

# cat redis-slave-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: redis-slave
spec:
  replicas: 2
  selector:
    name: redis-slave
  template:
    metadata:
      name: redis-slave
      labels:
        name: redis-slave
    spec:
      containers:
      - name: redis-slave
        image: registry.fjhb.cn/guestbook-redis-slave
        env:
        - name: GET_HOSTS_FROM
          value: env
        ports:
        - containerPort: 6379

# cat redis-slave-service.yaml 
apiVersion: v1
kind: Service
metadata:
  name: redis-slave
  labels:
    name: redis-slave
spec:
  ports:
  - port: 6379
  selector:
name: redis-slave

3、创建frontend的rc和service配置文件

# cat frontend-controller.yaml
apiVersion: v1
kind: ReplicationController
metadata:
  name: frontend
  labels:
    name: frontend
spec:
  replicas: 3
  selector:
    name: frontend
  template:
    metadata:
      labels:
        name: frontend
    spec:
      containers:
      - name: frontend
        image: registry.fjhb.cn/guestbook-php-frontend
        env:
        - name: GET_HOSTS_FROM
          value: env
        ports:
        - containerPort: 80

# cat frontend-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    name: frontend
spec:
  type: NodePort
  ports:
  - port: 80
    nodePort: 30001
  selector:
name: frontend

四、在master节点上创建rc 和 sevices

# kubectl create -f redis-master-controller.yaml 
# kubectl create -f redis-slave-controller.yaml 
# kubectl create -f frontend-controller.yaml 
# kubectl create -f redis-master-service.yaml 
# kubectl create -f redis-slave-service.yaml 
# kubectl create -f frontend-service.yaml 
# kubectl get rc
# kubectl get svc
# kubectl get pod

# kubectl describe pod redis-slave-gsk1p

无法创建pod的原因主要是无法从本地仓库中拉取镜像，即使本地已经存在了这个镜像，也是报这个错误。因为kubernetes的imagePullPolicy获取镜像策略默认值为Always

我们本地仓库的nginx配置了basic验证，故而报错如下
Error syncing pod, skipping: failed to "StartContainer" for "redis-slave" with ErrImagePull: "unauthorized: authentication required"
关闭nginx basic认证之后，再尝试一次，果然没有问题。

在Kubernetes中使用私有仓库并支持basic认证的最终解决方案是去配置kubernetes的serviceaccount，关于详细的配置将在后续的文章中进行介绍。

六、测试
1、查看redis master节点的redis集群信息

# kubectl exec redis-master-9993n redis-cli info |grep -A 5 "Replication"
# kubectl exec redis-slave-gnq41 redis-cli info |grep -A 5 "Replication" 
# kubectl exec redis-slave-nvscp redis-cli info |grep -A 5 "Replication" 

2、web测试

通过firebug插件可以看到是php+apache在提供web服务

七、 rc和service的删除

# kubectl delete -f frontend-controller.yaml
# kubectl delete -f redis-master-controller.yaml
# kubectl delete -f redis-slave-controller.yaml
# kubectl delete -f redis-slave-service.yaml
# kubectl delete -f redis-master-service.yaml
# kubectl delete -f frontend-service.yaml