在Kubernetes叢集中使用Redis部署PHP留言簿應用

實驗目標

• 啟動一個Redis Master
• 啟動一個Redis Slave
• 啟動guestbook程式
• 展示和檢視前端服務
• 清理

實驗環境

需要有一個Kubernetes叢集，以及kubectl命令列工具必須配置與叢集通訊

在此可以檢查k8s及相關工具版本：kubectl version

[[email protected] ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.2"
 
, GitCommit:"5fa2db2bd46ac79e5e00a4e6ed24191080aa463b", GitTreeState:"clean", BuildDate:"2018-01-18T10:09:24Z", GoVersion:"go1.9.2", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.2", GitCommit:"5fa2db2bd46ac79e5e00a4e6ed24191080aa463b", GitTreeState:"clean"
 
, BuildDate:"2018-01-18T09:42:01Z", GoVersion:"go1.9.2", Compiler:"gc", Platform:"linux/amd64"}

下載實驗用到的配置檔案：

筆者在k8s叢集master伺服器上建立了/opt/k8s/guestbook目錄，下載上面的檔案到目錄如下：

[[email protected]-k8s ~]# cd /opt/k8s/guestbook/
[[email protected]-k8s guestbook]# ll
total 24
-rw-r--r-- 1 root root 1086 Feb
 
  6 16:28 frontend-deployment.yaml
-rw-r--r-- 1 root root  438 Feb  6 16:29 frontend-service.yaml
-rw-r--r-- 1 root root  561 Feb  6 17:01 redis-master-deployment.yaml
-rw-r--r-- 1 root root  233 Feb  6 17:14 redis-master-service.yaml
-rw-r--r-- 1 root root 1117 Feb  6 16:28 redis-slave-deployment.yaml
-rw-r--r-- 1 root root  209 Feb  6 16:28 redis-slave-service.yaml

啟動Redis Master

留言簿應用程式使用Redis來儲存其資料。它將其資料寫入Redis主例項，並從多個Redis從例項中讀取資料

建立Redis Master部署配置檔案

清單檔案（如下所示）指定執行單個副本Redis master Pod的Deployment Controller。

• 在下載清單檔案的目錄中啟動一個終端視窗
• 從redis-master-deployment.yaml檔案應用Redis Master部署：

[root@aniu-k8s guestbook]# kubectl apply -f redis-master-deployment.yaml
Warning: kubectl apply should be used on resource created by either kubectl create --save-config or kubectl apply
deployment "redis-master" configured

• redis-master-deployment.yaml

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: redis-master
spec:
  selector:
    matchLabels:
      app: redis
      role: master
      tier: backend
  replicas: 1
  template:
    metadata:
      labels:
        app: redis
        role: master
        tier: backend
    spec:
      containers:
      - name: master
        image: k8s.gcr.io/redis:e2e  # or just image: redis
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
        - containerPort: 6379

• 查詢Pod的列表以驗證Redis Master Pod正在執行

[root@aniu-k8s guestbook]# kubectl get pods
NAME                            READY     STATUS    RESTARTS   AGE
redis-master-585798d8ff-g69wc   1/1       Running   0          28m

• 執行以下命令檢視Redis Master Pod中的日誌:

[root@aniu-k8s guestbook]# kubectl logs -f redis-master-585798d8ff-g69wc
                _._                                                  
           _.-``__ ''-._                                             
      _.-``    `.  `_.  ''-._           Redis 2.8.19 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in stand alone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6379
 |    `-._   `._    /     _.-'    |     PID: 1
  `-._    `-._  `-./  _.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |           http://redis.io        
  `-._    `-._`-.__.-'_.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |                                  
  `-._    `-._`-.__.-'_.-'    _.-'                                   
      `-._    `-.__.-'    _.-'                                       
          `-._        _.-'                                           
              `-.__.-'                                               
[1] 06 Feb 09:14:33.096 # Server started, Redis version 2.8.19
[1] 06 Feb 09:14:33.097 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
[1] 06 Feb 09:14:33.097 * The server is now ready to accept connections on port 6379

建立Redis Master服務

留言簿應用程式需要與Redis主站通訊以寫入其資料。您需要應用服務將流量代理到Redis主Pod。服務定義訪問Pod的策略

• 應用以下redis-master-service.yaml檔案中的Redis Master服務：

[root@aniu-k8s guestbook]# kubectl apply -f redis-master-service.yaml
service "redis-master" created

• redis-master-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    app: redis
    role: master
    tier: backend
spec:
  ports:
  - port: 6379
    targetPort: 6379
  selector:
    app: redis
    role: master
    tier: backend

• 查詢服務列表以驗證Redis主服務正在執行：

[root@aniu-k8s guestbook]# kubectl get service
NAME           TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
kubernetes     ClusterIP   10.96.0.1       <none>        443/TCP    6d
redis-master   ClusterIP   10.109.193.22   <none>        6379/TCP   6s

啟動Redis Slaves服務

雖然Redis master是一個單獨的pod，但是可以通過新增副本Redis Slaves來使其高度可用以滿足流量需求

建立Redis Slaves部署

部署根據清單檔案中設定的配置進行縮放。在這種情況下，Deployment物件指定兩個副本

如果沒有任何副本正在執行，則此部署將在您的容器群集上啟動兩個副本。相反，如果有兩個以上的副本正在執行，則會縮小直到兩個副本正在執行

• 從redis-slave-deployment.yaml檔案應用Redis Slave部署：

[root@aniu-k8s guestbook]# kubectl apply -f redis-slave-deployment.yaml
deployment "redis-slave" created

• redis-slave-deployment.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    app: redis
    role: master
    tier: backend
spec:
  ports:
  - port: 6379
    targetPort: 6379
  selector:
    app: redis
    role: master
    tier: backend
[[email protected] guestbook]# cat redis-slave-deployment.yaml 
apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: redis-slave
spec:
  selector:
    matchLabels:
      app: redis
      role: slave
      tier: backend
  replicas: 2
  template:
    metadata:
      labels:
        app: redis
        role: slave
        tier: backend
    spec:
      containers:
      - name: slave
        image: gcr.io/google_samples/gb-redisslave:v1
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
          # Using `GET_HOSTS_FROM=dns` requires your cluster to
          # provide a dns service. As of Kubernetes 1.3, DNS is a built-in
          # service launched automatically. However, if the cluster you are using
          # does not have a built-in DNS service, you can instead
          # instead access an environment variable to find the master
          # service's host. To do so, comment out the 'value: dns' line above, and
          # uncomment the line below:
          # value: env
        ports:
        - containerPort: 6379

• 查詢Pod的列表以驗證Redis Slave Pod是否正在執行：

[root@aniu-k8s guestbook]# kubectl get pods
NAME                            READY     STATUS              RESTARTS   AGE
redis-master-585798d8ff-g69wc   1/1       Running             0          3m
redis-slave-865486c9df-tjvfn    0/1       ContainerCreating   0          27s
redis-slave-865486c9df-x76gb    1/1       Running    

建立Redis Slave服務

留言簿應用程式需要與Redis Slave進行通訊以讀取資料。為了使Redis Slave可以被發現，需要建立一個服務。服務為一組Pod提供透明的負載平衡。

• 應用以下redis-slave-service.yaml檔案中的Redis從服務

[root@aniu-k8s guestbook]# kubectl apply -f redis-slave-service.yaml
service "redis-slave" created

• redis-slave-service.yaml

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

• 查詢服務列表以驗證Redis Slave服務是否正在執行

[[email protected] guestbook]# kubectl get services
NAME           TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
kubernetes     ClusterIP   10.96.0.1        <none>        443/TCP    6d
redis-master   ClusterIP   10.109.193.22    <none>        6379/TCP   2m
redis-slave    ClusterIP   10.101.252.227   <none>        6379/TCP   21s

設定和公開留言簿前端

留言簿應用程式有一個Web前端，用於使用PHP編寫的HTTP請求。它被配置為連線到redis-master服務的寫請求和redis-slave服務的讀請求

建立留言簿前端部署

• 從以下frontend-deployment.yaml檔案應用前端部署：

[root@aniu-k8s guestbook]# kubectl apply -f frontend-deployment.yaml
deployment "frontend" created

• frontend-deployment.yaml

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: frontend
spec:
  selector:
    matchLabels:
      app: guestbook
      tier: frontend
  replicas: 3
  template:
    metadata:
      labels:
        app: guestbook
        tier: frontend
    spec:
      containers:
      - name: php-redis
        image: gcr.io/google-samples/gb-frontend:v4
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
          # Using `GET_HOSTS_FROM=dns` requires your cluster to
          # provide a dns service. As of Kubernetes 1.3, DNS is a built-in
          # service launched automatically. However, if the cluster you are using
          # does not have a built-in DNS service, you can instead
          # instead access an environment variable to find the master
          # service's host. To do so, comment out the 'value: dns' line above, and
          # uncomment the line below:
          # value: env
        ports:
        - containerPort: 80

• 查詢Pod的列表以驗證三個前端副本正在執行：

[[email protected] guestbook]# kubectl get pods -l app=guestbook -l tier=frontend
NAME                       READY     STATUS    RESTARTS   AGE
frontend-67f65745c-lr25s   1/1       Running   0          1m
frontend-67f65745c-n798g   1/1       Running   0          1m
frontend-67f65745c-n92r4   1/1       Running   0          1m

建立前端服務

應用的redis-slave和redis-master服務只能在容器群集內訪問，因為服務的預設型別是ClusterIP。 ClusterIP為服務指向的一組Pod提供一個IP地址。 該IP地址只能在群集內訪問。

如果希望guest虛擬機器能夠訪問您的留言簿，則必須將前端服務配置為外部可見，以便客戶端可以從容器群集外部請求該服務。 Minikube只能通過NodePort公開服務

• 應用以下frontend-service.yaml檔案中的前端服務

[root@aniu-k8s guestbook]# kubectl apply -f frontend-service.yaml
service "frontend" created

• frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    app: guestbook
    tier: frontend
spec:
  # comment or delete the following line if you want to use a LoadBalancer
  type: NodePort 
  # if your cluster supports it, uncomment the following to automatically create
  # an external load-balanced IP for the frontend service.
  # type: LoadBalancer
  ports:
  - port: 80
  selector:
    app: guestbook
    tier: frontend

• 查詢服務列表以驗證前端服務正在執行

[[email protected] guestbook]# kubectl get services 
NAME           TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
frontend       NodePort    10.103.1.159     <none>        80:31546/TCP   7s
kubernetes     ClusterIP   10.96.0.1        <none>        443/TCP        6d
redis-master   ClusterIP   10.109.193.22    <none>        6379/TCP       5m
redis-slave    ClusterIP   10.101.252.227   <none>        6379/TCP       4m

通過NodePort檢視前端服務

如果您將此應用程式部署到Minikube或本地群集，則需要查詢IP地址才能檢視您的留言簿。

• 行以下命令獲取前端服務的IP地址

minikube service frontend --url

複製IP地址，然後在瀏覽器中載入頁面以檢視您的留言簿。

通過LoadBalancer檢視前端服務

• 執行以下命令獲取前端服務的IP地址

[root@aniu-k8s guestbook]# kubectl get service frontend

複製外部IP地址，並在瀏覽器中載入頁面以檢視您的留言簿

擴充套件Web前端

放大或縮小很容易，因為我們的伺服器被定義為使用部署控制器的服務

• 執行以下命令以放大前端Pod的數量

[root@aniu-k8s guestbook]# kubectl scale deployment frontend --replicas=5
deployment "frontend" scaled

• 查詢Pod的列表以驗證正在執行的前端Pod的數量：

[[email protected] guestbook]# kubectl get pods
NAME                            READY     STATUS    RESTARTS   AGE
frontend-67f65745c-lr25s        1/1       Running   0          5m
frontend-67f65745c-n798g        1/1       Running   0          5m
frontend-67f65745c-n92r4        1/1       Running   0          5m
frontend-67f65745c-nsnfs        1/1       Running   0          7s
frontend-67f65745c-spjnm        1/1       Running   0          7s
redis-master-585798d8ff-g69wc   1/1       Running   0          10m
redis-slave-865486c9df-tjvfn    1/1       Running   0          8m
redis-slave-865486c9df-x76gb    1/1       Running   0          8m

• 執行以下命令以縮小前端Pod的數量：

[[email protected] guestbook]# kubectl scale deployment frontend --replicas=2
deployment "frontend" scaled
[[email protected] guestbook]# kubectl get pods
NAME                            READY     STATUS        RESTARTS   AGE
frontend-67f65745c-lr25s        1/1       Running       0          50m
frontend-67f65745c-n798g        1/1       Running       0          50m
frontend-67f65745c-n92r4        0/1       Terminating   0          50m
frontend-67f65745c-spjnm        0/1       Terminating   0          45m
redis-master-585798d8ff-g69wc   1/1       Running       0          56m
redis-slave-865486c9df-tjvfn    1/1       Running       0          53m
redis-slave-865486c9df-x76gb    1/1       Running       0          53m

清理pods及services

刪除部署和服務也會刪除任何正在執行的Pod。使用標籤可以用一個命令刪除多個資源。

• 執行以下命令刪除所有Pod，Deployments和Services。

kubectl delete deployment -l app=redis
kubectl delete service -l app=redis
kubectl delete deployment -l app=guestbook
kubectl delete service -l app=guestbook

• 回顯如下：

deployment "redis-master" deleted
deployment "redis-slave" deleted
service "redis-master" deleted
service "redis-slave" deleted
deployment "frontend" deleted    
service "frontend" deleted

• 查詢Pod的列表以驗證沒有Pod正在執行：

kubectl get pods
# 
No resources found.