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: #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:
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 48s
查看pods信息：
[root@uat-app01 k8s_yaml]# kubectl get pods
NAME READY STATUS RESTARTS AGE
redis-master-2qftt / ContainerCreating 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, Dec :: +
Labels: name=redis-master
Status: Pending
IP:
Controllers: ReplicationController/redis-master
Containers:
master:
Container ID:
Image: kubeguide/redis-master
Image ID:
Port: /TCP
State: Waiting
Reason: ContainerCreating
Ready: False
Restart Count:
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 {default-scheduler } Normal Scheduled Successfully assigned redis-master-2qftt to uat-ucs02.insightcredit
3m 18s {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 {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: #服务监听的端口号
targetPort: #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> /TCP 5h
redis-master 10.254.227.87 <none> /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:
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:
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 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:
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> /TCP 5h
redis-master 10.254.227.87 <none> /TCP 29m
redis-slave 10.254.71.156 <none> /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:
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:
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: #服务监听的端口号
nodePort: #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 / Running 15h
frontend-kmth2 / Running 15h
frontend-vltkp / Running 15h
redis-master-f59zp / Running 15h
redis-slave-6rxl8 / Running 15h
redis-slave-j4jz0 / Running 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。