基于Kubernetess集群部署完整示例——Guestbook

目录贴：Kubernetes学习系列

　　本文依赖环境：Centos7部署Kubernetes集群、基于Kubernetes集群部署skyDNS服务

　　该示例中，我们将创建一个redis-master、两个redis-slave、三个frontend。其中，slave会实时备份master中数据，frontend会向master中写数据，之后会从slave中读取数据。所有系统间的调用（例如slave找master同步数据；frontend找master写数据；frontend找slave读数据等），采用的是dns方式实现。

1、准备工作

1.1镜像准备

　　本示例中依赖以下几个镜像，请提前准备好：

docker.io/redis:latest                                1a8a9ee54eb7

registry.access.redhat.com/rhel7/pod-infrastructure:latest   34d3450d733b

gcr.io/google_samples/gb-frontend:v3                  c038466384ab

gcr.io/google_samples/gb-redisslave:v1                 5f026ddffa27

1.2环境准备

　　需要一套kubernetes运行环境，及Cluster DNS，如下：

[root@k8s-master ~]# kubectl cluster-info
Kubernetes master is running at http://localhost:8080
KubeDNS is running at http://localhost:8080/api/v1/proxy/namespaces/kube-system/services/kube-dns
kubernetes-dashboard is running at http://localhost:8080/api/v1/proxy/namespaces/kube-system/services/kubernetes-dashboard

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
[root@k8s-master ~]# kubectl get componentstatus
NAME                 STATUS    MESSAGE              ERROR
scheduler            Healthy   ok
controller-manager   Healthy   ok
etcd-               Healthy   {"health": "true"}
[root@k8s-master ~]# kubectl get nodes
NAME         STATUS    AGE
k8s-node-   Ready     7d
k8s-node-   Ready     7d
[root@k8s-master ~]#  kubectl get deployment --all-namespaces
NAMESPACE     NAME                          DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
kube-system   kube-dns                                                               5d
kube-system   kubernetes-dashboard-latest                                            6d
[root@k8s-master ~]#

2、运行redis-master

2.1yaml文件

　　1）redis-master-controller.yaml

apiVersion: v1
kind: ReplicationController
metadata:
  name: redis-master
  labels:
    name: redis-master
spec:
  replicas:
  selector:
    name: redis-master
  template:
    metadata:
      labels:
        name: redis-master
    spec:
      containers:
      - name: master
        image: redis
        ports:
        - containerPort: 

　　2）redis-master-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    name: redis-master
spec:
  ports:
    # the port that this service should serve on
  - port:
    targetPort:
  selector:
    name: redis-master

2.2创建rc及service

　　Master上执行：

[root@k8s-master yaml]# kubectl create -f redis-master-controller.yaml
replicationcontroller " redis-master" created
[root@k8s-master yaml]# kubectl create -f redis-master-service.yaml
service " redis-master" created
[root@k8s-master yaml]# kubectl get rc
NAME           DESIRED   CURRENT   READY     AGE
redis-master                              1d
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
redis-master-5wyku   /       Running             1d

3、运行redis-slave

3.1yaml文件

　　1）redis-slave-controller.yaml

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: worker
        image: gcr.io/google_samples/gb-redisslave:v1
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 

　　2）redis-slave-service.yaml

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

3.2创建rc及service

　　Master上执行：

[root@k8s-master yaml]# kubectl create -f redis-slave-controller.yaml
replicationcontroller "redis-slave" created
[root@k8s-master yaml]# kubectl create -f redis-slave-service.yaml
service "redis-slave" created
[root@k8s-master yaml]# kubectl get rc
NAME           DESIRED   CURRENT   READY     AGE
redis-master                              1d
redis-slave                               44m
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
redis-master-5wyku   /       Running             1d
redis-slave-7h295    /       Running             44m
redis-slave-r355y    /       Running             44m

4、运行frontend

4.1yaml文件

　　1）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: gcr.io/google_samples/gb-frontend:v3
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 

　　2）frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    name: fronted
spec:
  type: NodePort
  ports:
  - port:
    nodePort:
  selector:
    name: frontend

4.2创建rc及service

　　Master上执行：

[root@k8s-master yaml]# kubectl create -f frontend-controller.yaml
replicationcontroller "frontend" created
[root@k8s-master yaml]# kubectl create -f frontend-service.yaml
service "frontend" created
[root@k8s-master yaml]# kubectl get rc
NAME           DESIRED   CURRENT   READY     AGE
frontend                                  28m
redis-master                              1d
redis-slave                               44m
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
frontend-ax654       /       Running             29m
frontend-k8caj       /       Running             29m
frontend-x6bhl       /       Running             29m
redis-master-5wyku   /       Running             1d
redis-slave-7h295    /       Running             44m
redis-slave-r355y    /       Running             44m
[root@k8s-master yaml]# kubectl get service
NAME            CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
frontend        10.254.93.91     <nodes>       /TCP     47m
kubernetes      10.254.0.1       <none>        /TCP    7d
redis-master    10.254.132.210   <none>        /TCP   1d
redis-slave     10.254.104.23    <none>        /TCP   1h

4.3页面验证

　　至此，Guestbook已经运行在了kubernetes中了，但是外部是无法通过通过frontend-service的IP10.0.93.91这个IP来进行访问的。Service的虚拟IP是kubernetes虚拟出来的内部网络，在外部网络中是无法寻址到的，这时候就需要增加一层外网到内网的网络转发。我们的示例中采用的是NodePort的方式实现的，之前在创建frontend-service时设置了nodePort: 30001，即kubernetes将会在每个Node上设置端口，成为NodePort，通过NodePort端口可以访问到真正的服务。