kubernetes集群应用部署实例

今天，我们将要带来入门hello world示例，它是一个web留言板应用，基于PHP+Redis的两层分布式架构的web应用，前端PHP web网站通过访问后端Redis数据库完成用户留言的查询和添加功能，具备读写分离能力，留言板内容是从redis中查询到的，首页中添加留言并提交后，留言会被添加到redis中。

有三个前端节点：php-frontend，对网站的访问进行负载均衡

有两个redis后端节点：一个redis-master和两个redis-slave，两个redis-slave从redis-master进行同步数据

php-frontend进行了读写分离，即在写入的时候写入主库，而读取的时候从从库读取。

客户通过客户端访问的时候，访问前端相应的地址即可。

 

整体的架构是这个样子：

1.创建redis-master Pod和服务

先定义RC来创建pod,然后定义与之关联的service。

为redis-master服务新建一个名为redis-master-controller.yaml的replicationcontroller定义文件,内容为:

[root@uat-app01 etc]# mkdir /etc/k8s_yaml
[root@uat-app01 k8s_yaml]# vim /etc/k8s_yaml/redis-master-controller.yaml
apiVersion: v1    #指定api版本号
kind: ReplicationController    #创建资源的类型：这里为ReplicationController
metadata:    #资源元数据
  name: redis-master    #资源名称
  labels:     #资源标签
    name: redis-master    #标签名
spec:     #容器的详细定义
  replicas: 1    #副本数量：这里为1
  selector:     #RC通过spec.selector来筛选要控制的Pod
    name: redis-master
  template:    # pod的定义
    metadata:  # pod元数据
      labels:    #pod标签
        name: redis-master
    spec:     #指定资源内容
      containers:    #容器
      - name: master    #容器名
        image: kubeguide/redis-master    #使用的镜像
        ports:     #容器开放对外的端口号：这里为6379
          - containerPort: 6379

创建好文件后，执行如下命令：

[root@uat-app01 k8s_yaml]# kubectl create -f /etc/k8s_yaml/redis-master-controller.yaml 
replicationcontroller "redis-master" created

查看刚才新建的RC信息：

[root@uat-app01 k8s_yaml]# kubectl get rc
NAME           DESIRED   CURRENT   READY     AGE
redis-master   1         1         0         48s

查看pods信息：

[root@uat-app01 k8s_yaml]# kubectl get pods
NAME                 READY     STATUS              RESTARTS   AGE
redis-master-2qftt   0/1       ContainerCreating   0          1m

查看pod redis-master-2qftt 信息：

[root@uat-app01 k8s_yaml]# kubectl describe pod redis-master-2qftt
Name:        redis-master-2qftt
Namespace:    default
Node:        uat-ucs02.insightcredit/192.168.1.47
Start Time:    Wed, 20 Dec 2017 15:27:07 +0800
Labels:        name=redis-master
Status:        Pending
IP:        
Controllers:    ReplicationController/redis-master
Containers:
  master:
    Container ID:        
    Image:            kubeguide/redis-master
    Image ID:            
    Port:            6379/TCP
    State:            Waiting
      Reason:            ContainerCreating
    Ready:            False
    Restart Count:        0
    Volume Mounts:        <none>
    Environment Variables:    <none>
Conditions:
  Type        Status
  Initialized     True 
  Ready     False 
  PodScheduled     True 
No volumes.
QoS Class:    BestEffort
Tolerations:    <none>
Events:
  FirstSeen    LastSeen    Count    From                    SubObjectPath    Type        Reason        Message
  ---------    --------    -----    ----                    -------------    --------    ------        -------
  3m        3m        1    {default-scheduler }                    Normal        Scheduled    Successfully assigned redis-master-2qftt to uat-ucs02.insightcredit
  3m        18s        5    {kubelet uat-ucs02.insightcredit}            Warning        FailedSync    Error syncing pod, skipping: failed to "StartContainer" for "POD" with ErrImagePull: "image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials on this request.  details: (open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory)"

  2m    7s    10    {kubelet uat-ucs02.insightcredit}        Warning    FailedSync    Error syncing pod, skipping: failed to "StartContainer" for "POD" with ImagePullBackOff: "Back-off pulling image "registry.access.redhat.com/rhel7/pod-infrastructure:latest""

这里看到是发生了异常的：

在pull registry.access.redhat.com/rhel7/pod-infrastructure:latest 镜像时出现问题，问题原因是 /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt文件不存在

尝试去pull这个镜像，发现缺失文件/etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt

[root@uat-app01 k8s_yaml]# docker pull registry.access.redhat.com/rhel7/pod-infrastructure:latest
Trying to pull repository registry.access.redhat.com/rhel7/pod-infrastructure ... 
open /etc/docker/certs.d/registry.access.redhat.com/redhat-ca.crt: no such file or directory

查看该缺失的文件，发现为软连接，缺少名叫rhsm的依赖，查找关于rhsm的依赖包

经过查阅发现，该缺少的rhsm包为：python-rhsm

使用yum安装

[root@uat-ucs01 kubernetes]# yum install python-rhsm.x86_64 0:1.19.10-1.el7_4

安装后，该文件存在，问题解决

创建于redis-master pod相关联的service，文件内容如下：

[root@uat-app01 k8s_yaml]# vi /etc/k8s_yaml/redis-master-service.yaml

apiVersion: v1
kind: Service
metadata: 
  name: redis-master
  labels:
    name: redis-master
spec:
  ports:
  - port: 6379    #服务监听的端口号
    targetPort: 6379    #需要转发到后端pod的端口号，就是容器对外开放的端口号
  selector:
    name: redis-master

创建service：

[root@uat-app01 k8s_yaml]# kubectl create -f /etc/k8s_yaml/redis-master-service.yaml 
service "redis-master" created

查看新建的service:

[root@uat-app01 k8s_yaml]# kubectl get services
NAME           CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
kubernetes     10.254.0.1      <none>        443/TCP    5h
redis-master   10.254.227.87   <none>        6379/TCP   1m

2.创建redis-slave Pod和服务

为redis-slave服务新建一个名为redis-slave-controller.yaml的replicationcontroller定义文件,内容为:

apiVersion: v1
kind: ReplicationController
metadata:
  name: redis-slave
  labels:
    name: redis-slave
spec:
  replicas: 2
  selector:
    name: redis-slave
  template:
    metadata:
      labels:
        name: redis-slave
    spec: 
      containers:
      - name: slave
        image: kubeguide/guestbook-redis-slave
        env:
        - name: GET_HOSTS_FROM
          value: env
        ports:
        - containerPort: 6379

创建好文件后，执行如下命令:

[root@uat-app01 k8s_yaml]# kubectl create -f /etc/k8s_yaml/redis-slave-controller.yaml 
replicationcontroller "redis-slave" created

查看刚才新建的RC信息：

[root@uat-app01 k8s_yaml]# kubectl get rc redis-slave
NAME          DESIRED   CURRENT   READY     AGE
redis-slave   2         2         0         39s

配置文件redis-salve-service.yaml内容如下:

[root@uat-app01 k8s_yaml]# vim /etc/k8s_yaml/redis-slave-service.yaml 

apiVersion: v1
kind: Service
metadata:
  name: redis-slave
  labels:
    name: redis-slave
spec:
  ports:
  - port: 6379
  selector:
    name: redis-slave

创建service：

[root@uat-app01 k8s_yaml]# kubectl create -f redis-slave-service.yaml
service "redis-slave" created

检查service：

[root@uat-app01 k8s_yaml]# kubectl get service
NAME           CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
kubernetes     10.254.0.1      <none>        443/TCP    5h
redis-master   10.254.227.87   <none>        6379/TCP   29m
redis-slave    10.254.71.156   <none>        6379/TCP   35s

3.创建fronted pod和服务

创建frontend的rc

[root@uat-app01 k8s_yaml]#  vi /etc/k8s_yaml/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: kubeguide/guestbook-php-frontend
        env: 
        - name: GET_HOSTS_FROM
          value: env
        ports:
        - containerPort: 80

创建rc

[root@uat-app01 k8s_yaml]#  kubectl create -f /etc/k8s_yaml/frontend-controller.yaml
replicationcontroller "frontend" created

创建frontend的service，前端的service是需要外部访问的，所以进行如下配置

[root@uat-app01 k8s_yaml]# vi /etc/k8s_yaml/frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    name: frontend
spec:
  type: NodePort    #外部访问端口形式为：通过node端口形式进行访问
  ports:
  - port: 80    #服务监听的端口号
    nodePort: 30001    #node上开放的外部端口
  selector:
    name: frontend
[root@uat-app01 k8s_yaml]# kubectl create -f /etc/k8s_yaml/frontend-service.yaml
service "frontend" created

创建好以上rc、pod、service后查看pod情况

[root@uat-app01 ~]# kubectl get pods
NAME                 READY     STATUS    RESTARTS   AGE
frontend-3bv0p       1/1       Running   0          15h
frontend-kmth2       1/1       Running   0          15h
frontend-vltkp       1/1       Running   0          15h
redis-master-f59zp   1/1       Running   0          15h
redis-slave-6rxl8    1/1       Running   0          15h
redis-slave-j4jz0    1/1       Running   0          15h

在浏览器中输入任意运行frontend的pod的ip地址加上我们定义好的node port 30001

我这里是192.168.1.40:30001

留言板出现了，快来提交我们的留言吧~

hello world

kubernetes的hello world实例到此完成啦。

转载：http://www.louisvv.com/archives/1179.html