基於Kubernetess叢集部署完整示例——Guestbook

振宇要低調發表於2017-03-04

　　本文依賴環境：Centos7部署Kubernetes叢集、基於Kubernetes叢集部署skyDNS服務

　　該示例中，我們將建立一個redis-master、兩個redis-slave、三個frontend。其中，slave會實時備份master中資料，frontend會向master中寫資料，之後會從slave中讀取資料。所有系統間的呼叫（例如slave找master同步資料；frontend找master寫資料；frontend找slave讀資料等），採用的是dns方式實現。

 

1、準備工作

1.1映象準備

　　本示例中依賴以下幾個映象，請提前準備好：

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環境準備

　　需要一套kubernetes執行環境，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-0               Healthy   {"health": "true"}   
[root@k8s-master ~]# kubectl get nodes
NAME         STATUS    AGE
k8s-node-1   Ready     7d
k8s-node-2   Ready     7d
[root@k8s-master ~]#  kubectl get deployment --all-namespaces
NAMESPACE     NAME                          DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
kube-system   kube-dns                      1         1         1            1           5d
kube-system   kubernetes-dashboard-latest   1         1         1            1           6d
[root@k8s-master ~]#

 

2、執行redis-master

2.1yaml檔案

　　1）redis-master-controller.yaml

apiVersion: v1
kind: ReplicationController
metadata:
  name: redis-master
  labels:
    name: redis-master
spec:
  replicas: 1
  selector:
    name: redis-master
  template:
    metadata:
      labels:
        name: redis-master
    spec:
      containers:
      - name: master
        image: redis
        ports:
        - containerPort: 6379

　　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: 6379
    targetPort: 6379
  selector:
    name: redis-master

2.2建立rc及service

　　Master上執行：

[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   1         1         1         1d
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
redis-master-5wyku   1/1       Running   0          1d

 

3、執行redis-slave

3.1yaml檔案

　　1）redis-slave-controller.yaml

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: worker
        image: gcr.io/google_samples/gb-redisslave:v1 
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 6379

　　2）redis-slave-service.yaml

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

3.2建立rc及service

　　Master上執行：

[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   1         1         1         1d
redis-slave    2         2         2         44m
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
redis-master-5wyku   1/1       Running   0          1d
redis-slave-7h295    1/1       Running   0          44m
redis-slave-r355y    1/1       Running   0          44m

 

4、執行frontend

4.1yaml檔案

　　1）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: gcr.io/google_samples/gb-frontend:v3  
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 80

　　2）frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    name: fronted
spec:
  type: NodePort
  ports:
  - port: 80
    nodePort: 30001
  selector:
    name: frontend

4.2建立rc及service

　　Master上執行：

[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       3         3         3         28m
redis-master   1         1         1         1d
redis-slave    2         2         2         44m
[root@k8s-master yaml]# kubectl get pod
NAME                 READY     STATUS    RESTARTS   AGE
frontend-ax654       1/1       Running   0          29m
frontend-k8caj       1/1       Running   0          29m
frontend-x6bhl       1/1       Running   0          29m
redis-master-5wyku   1/1       Running   0          1d
redis-slave-7h295    1/1       Running   0          44m
redis-slave-r355y    1/1       Running   0          44m
[root@k8s-master yaml]# kubectl get service
NAME            CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
frontend        10.254.93.91     <nodes>       80/TCP     47m
kubernetes      10.254.0.1       <none>        443/TCP    7d
redis-master    10.254.132.210   <none>        6379/TCP   1d
redis-slave     10.254.104.23    <none>        6379/TCP   1h

4.3頁面驗證

　　至此，Guestbook已經執行在了kubernetes中了，但是外部是無法通過通過frontend-service的IP10.0.93.91這個IP來進行訪問的。Service的虛擬IP是kubernetes虛擬出來的內部網路，在外部網路中是無法定址到的，這時候就需要增加一層外網到內網的網路轉發。我們的示例中採用的是NodePort的方式實現的，之前在建立frontend-service時設定了nodePort: 30001，即kubernetes將會在每個Node上設定埠，成為NodePort，通過NodePort埠可以訪問到真正的服務。

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