Deployment YAML方式創建Nginx服務

replication controller

Replication Controller為Kubernetes的一個核心內容，應用托管到Kubernetes之后，需要保證應用能夠持續的運行，Replication Controller就是這個保證的key，主要的功能如下：

1.確保pod數量：它會確保Kubernetes中有指定數量的Pod在運行。如果少於指定數量的pod，Replication Controller會創建新的，反之則會刪除掉多余的以保證Pod數量不變。
2.確保pod健康：當pod不健康，運行出錯或者無法提供服務時，Replication Controller也會殺死不健康的pod，重新創建新的。
3.彈性伸縮 ：在業務高峰或者低峰期的時候，可以通過Replication Controller動態的調整pod的數量來提高資源的利用率。同時，配置相應的監控功能（Hroizontal Pod Autoscaler），會定時自動從監控平台獲取Replication Controller關聯pod的整體資源使用情況，做到自動伸縮。
4.滾動升級：滾動升級為一種平滑的升級方式，通過逐步替換的策略，保證整體系統的穩定，在初始化升級的時候就可以及時發現和解決問題，避免問題不斷擴大。

Deployment

Deployment同樣為Kubernetes的一個核心內容，主要職責同樣是為了保證pod的數量和健康，90%的功能與Replication Controller完全一樣，可以看做新一代的Replication Controller。但是，它又具備了Replication Controller之外的新特性： 

1.Replication Controller全部功能：Deployment繼承了上面描述的Replication Controller全部功能。 
2.事件和狀態查看：可以查看Deployment的升級詳細進度和狀態。 
3.回滾：當升級pod鏡像或者相關參數的時候發現問題，可以使用回滾操作回滾到上一個穩定的版本或者指定的版本。 
4.版本記錄: 每一次對Deployment的操作，都能保存下來，給予后續可能的回滾使用。 
5.暫停和啟動：對於每一次升級，都能夠隨時暫停和啟動。 
6.多種升級方案：Recreate：刪除所有已存在的pod,重新創建新的; RollingUpdate：滾動升級，逐步替換的策略，同時滾動升級時，支持更多的附加參數，例如設置最大不可用pod數量，最小升級間隔時間等等。

1、創建deployment
[root@linux-node1 ~]# vim nginx-deployment.yaml　　#使用yaml的方式進行創建應用
apiVersion: apps/v1　　#apiVersion是當前配置格式的版本
kind: Deployment　　　　#kind是要創建的資源類型，這里是Deploymnet
metadata:　　　　　　　　#metadata是該資源的元數據，name是必須的元數據項
  name: nginx-deployment
  labels:
    app: nginx
spec:　　　　　　　　　　#spec部分是該Deployment的規則說明
  replicas: 3　　　　　 #relicas指定副本數量，默認為1
  selector:
    matchLabels:
      app: nginx
  template:　　　　　　#template定義Pod的模板，這是配置的重要部分
    metadata:　　　　  #metadata定義Pod的元數據，至少要頂一個label，label的key和value可以任意指定
      labels:
        app: nginx
    spec:　　　　　　　#spec描述的是Pod的規則，此部分定義pod中每一個容器的屬性，name和image是必需的
      containers:
      - name: nginx
        image: nginx:1.13.12
        ports:
        - containerPort: 80

[root@linux-node1 ~]# kubectl create -f nginx-deployment.yaml #創建nginx-deployment應用
deployment.apps "nginx-deployment" created

2、查看deployment

[root@linux-node1 ~]# kubectl get deployment
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
net-test           2         2         2            2           32m
nginx-deployment   3         3         3            0           10s
   
[root@linux-node1 ~]# kubectl describe deployment nginx-deployment    #查看deployment詳情
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Thu, 16 Aug 2018 16:13:37 +0800
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision=1
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 0 available | 3 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:1.13.12
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-6c45fc49cb (3/3 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  1m    deployment-controller  Scaled up replica set nginx-deployment-6c45fc49cb to 3

3、查看Pod

[root@linux-node1 ~]# kubectl get pod    #查看pod在狀態，正在創建中，此時應該正在拉取鏡像
NAME                                READY     STATUS              RESTARTS   AGE
net-test-5767cb94df-djt98           1/1       Running             0          22m
net-test-5767cb94df-hcwv7           1/1       Unknown             0          34m
net-test-5767cb94df-zb8m4           1/1       Running             0          34m
nginx-deployment-6c45fc49cb-dmc22   0/1       ContainerCreating   0          2m
nginx-deployment-6c45fc49cb-fd8xm   0/1       ContainerCreating   0          2m
nginx-deployment-6c45fc49cb-sc8sh   0/1       ContainerCreating   0          2m
   
[root@linux-node1 ~]# kubectl describe pod nginx-deployment-6c45fc49cb-dmc22  #查看具體某個pod的狀態信息
   
[root@linux-node1 ~]# kubectl get pod -o wide　　#創建成功，狀態為Running
NAME                                READY     STATUS    RESTARTS   AGE       IP          NODE
net-test-5767cb94df-djt98           1/1       Running   0          24m       10.2.73.3   192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          36m       10.2.10.2   192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          36m       10.2.73.2   192.168.56.13
nginx-deployment-6c45fc49cb-dmc22   1/1       Running   0          4m        10.2.73.6   192.168.56.13
nginx-deployment-6c45fc49cb-fd8xm   1/1       Running   0          4m        10.2.73.4   192.168.56.13
nginx-deployment-6c45fc49cb-sc8sh   1/1       Running   0          4m        10.2.73.5   192.168.56.13

Deployment、ReplicaSet、Pod 都已經就緒。如果要刪除這些資源，執行 kubectl delete deployment nginx-deployment 或者 kubectl delete -f nginx-deployment.yaml。

4、測試Pod訪問
[root@linux-node1 ~]# curl --head http://10.2.73.6
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:18:14 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

5、更新Deployment

[root@linux-node1 ~]# kubectl set image deployment/nginx-deployment nginx=nginx:1.15.2 --record    #nginx的版本升級，由1.13.2升級為1.15.2，記錄需要加參數--record
deployment.apps "nginx-deployment" image updated
   
[root@linux-node1 ~]# kubectl get deployment -o wide　　#查看更新后的deployment，可以看到當前4個副本，說明還在滾動升級中
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE       CONTAINERS   IMAGES         SELECTOR
net-test           2         2         2            2           39m       net-test     alpine         run=net-test
nginx-deployment   3         4         1            3           6m        nginx        nginx:1.15.2   app=nginx

6、查看更新歷史
[root@linux-node1 ~]# kubectl rollout history deployment/nginx-deployment #查看更新歷史記錄
deployments "nginx-deployment"
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployment/nginx-deployment nginx=nginx:1.15.2 --record=true

7、查看具體某一個版本的升級歷史

[root@linux-node1 ~]# kubectl rollout history deployment/nginx-deployment --revision=1
deployments "nginx-deployment" with revision #1
Pod Template:
  Labels:    app=nginx
    pod-template-hash=2701970576
  Containers:
   nginx:
    Image:    nginx:1.13.12
    Port:    80/TCP
    Host Port:    0/TCP
    Environment:    <none>
    Mounts:    <none>
  Volumes:    <none>

8、查看更新后的Deployment，並進行訪問

[root@linux-node1 ~]# kubectl get pod -o wide
NAME                                READY     STATUS    RESTARTS   AGE       IP          NODE
net-test-5767cb94df-djt98           1/1       Running   0          30m       10.2.73.3   192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          42m       10.2.10.2   192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          42m       10.2.73.2   192.168.56.13
nginx-deployment-64749d4b59-djttr   1/1       Running   0          37s       10.2.73.8   192.168.56.13
nginx-deployment-64749d4b59-jp7fw   1/1       Running   0          3m        10.2.73.7   192.168.56.13
nginx-deployment-64749d4b59-q4fsn   1/1       Running   0          33s       10.2.73.9   192.168.56.13
[root@linux-node1 ~]# curl --head http://10.2.73.7
HTTP/1.1 200 OK
Server: nginx/1.15.2　　#版本已經升級為1.15.2
Date: Thu, 16 Aug 2018 08:24:09 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 24 Jul 2018 13:02:29 GMT
Connection: keep-alive
ETag: "5b572365-264"
Accept-Ranges: bytes

9、快速回滾到上一個版本

[root@linux-node1 ~]# kubectl rollout undo deployment/nginx-deployment   #回滾上一個版本
deployment.apps "nginx-deployment"    
   
[root@linux-node1 ~]# kubectl get pod -o wide
NAME                                READY     STATUS    RESTARTS   AGE       IP           NODE
net-test-5767cb94df-djt98           1/1       Running   0          32m       10.2.73.3    192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          43m       10.2.10.2    192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          43m       10.2.73.2    192.168.56.13
nginx-deployment-6c45fc49cb-b9h84   1/1       Running   0          24s       10.2.73.11   192.168.56.13
nginx-deployment-6c45fc49cb-g4mrg   1/1       Running   0          26s       10.2.73.10   192.168.56.13
nginx-deployment-6c45fc49cb-k29kq   1/1       Running   0          21s       10.2.73.12   192.168.56.13
[root@linux-node1 ~]# curl --head http://10.2.73.10
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:25:35 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

回滾完成，每一次更新或者回滾ip都會變化，所以需要通過vip進行訪問，這就引入了service   

10、使用service的vip進行訪問應用

[root@linux-node1 ~]# vim nginx-service.yaml　　#使用yaml方式創建service
kind: Service
apiVersion: v1
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

[root@linux-node1 ~]# kubectl create -f nginx-service.yaml 　　#創建service
service "nginx-service" created

[root@linux-node1 ~]# kubectl get service
NAME            TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
kubernetes      ClusterIP   10.1.0.1       <none>        443/TCP   4h
nginx-service   ClusterIP   10.1.213.126   <none>        80/TCP    15s　　#這個就是vip

[root@linux-node2 ~]# curl --head http://10.1.213.126　　#在node2節點上進行訪問vip測試，在node1上無法訪問是因為沒有安裝kube-proxy導致無法訪問
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:30:08 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

11、擴容到5個節點

[root@linux-node1 ~]# kubectl scale deployment nginx-deployment --replicas 5　　#對應用的副本數進行擴容，直接指定副本數為5
deployment.extensions "nginx-deployment" scaled

[root@linux-node1 ~]# kubectl get pod　　#查看pod狀態，可以看到已經增加到5個副本
NAME                                READY     STATUS    RESTARTS   AGE
net-test-5767cb94df-djt98           1/1       Running   0          38m
net-test-5767cb94df-hcwv7           1/1       Unknown   0          50m
net-test-5767cb94df-zb8m4           1/1       Running   0          50m
nginx-deployment-6c45fc49cb-b9h84   1/1       Running   0          6m
nginx-deployment-6c45fc49cb-g4mrg   1/1       Running   0          7m
nginx-deployment-6c45fc49cb-k29kq   1/1       Running   0          6m
nginx-deployment-6c45fc49cb-n9qkx   1/1       Running   0          24s
nginx-deployment-6c45fc49cb-xpx9s   1/1       Running   0          24s

##擴容與減容

　 #kubectl get deployment ##獲取deployment名稱
  #kubectl scale deployment nginx-deployment --replicas=3 擴容到3個
  #kubectl scale deployment nginx-deployment --replicas=1 恢復成1個

##動態處理CPU資源

#kubectl autoscale deployment nginx-deployment --min=2 --max=10 --cpu-percent=80