Kubernetes之deployment詳解

1.deployment介紹

為了更好地解決服務編排的問題，k8s在V1.2版本開始，引入了deployment控制器，值得一提的是，這種控制器並不直接管理pod，

而是通過管理replicaset來間接管理pod，即：deployment管理replicaset，replicaset管理pod。所以deployment比replicaset的功能更強大。

 

 

 

deployment的主要功能有下面幾個：

• 支持replicaset的所有功能
• 支持版本的滾動更新和版本回退
• 支持發布的停止、繼續

 

deployment的資源清單文件

apiVersion: apps/v1  #版本號
kind: Deployment  #類型
metadata:    #元數據
  name:    #rs名稱
  namespace:   #所屬命名空間
  labels:   #標簽
    controller: deploy
spec:   #詳情描述
  replicas:  #副本數量
  revisionHistoryLimit: #保留歷史版本，默認是10
  paused: #暫停部署，默認是false
  progressDeadlineSeconds: #部署超時時間(s)，默認是600
  strategy: #策略
    type: RollingUpdates  #滾動更新策略
    rollingUpdate:  #滾動更新
      maxSurge: #最大額外可以存在的副本數，可以為百分比，也可以為整數
      maxUnavaliable: #最大不可用狀態的pod的最大值，可以為百分比，也可以為整數
  selector:  #選擇器，通過它指定該控制器管理哪些pod
    matchLabels:   #Labels匹配規則
       app: nginx-pod
    matchExpressions:   #Expression匹配規則
      - {key: app, operator: In, values: [nginx-pod]}
  template:  #模板，當副本數量不足時，會根據下面的模板創建pod副本
    metadata:
        labels:
          app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80

2.deployment創建

1）nginx-deployment.yaml，內容如下：

[root@k8s-master yaml]# cat nginx-deployment.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: default
spec:
  replicas: 3
  selector:
    matchLabels:
     app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

 

 

2）執行創建

[root@k8s-master yaml]# kubectl apply -f nginx-deployment.yaml
[root@k8s-master yaml]# kubectl get deploy,rs,po -o wide
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
deployment.apps/nginx-deployment   3/3     3            3           41s   nginx        nginx:1.17.1   app=nginx-pod

NAME                                          DESIRED   CURRENT   READY   AGE   CONTAINERS   IMAGES         SELECTOR
replicaset.apps/nginx-deployment-5d9c9b97bb   3         3         3       41s   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb

NAME                                    READY   STATUS    RESTARTS   AGE   IP               NODE        NOMINATED NODE   READINESS GATES
pod/nginx-deployment-5d9c9b97bb-4p2hx   1/1     Running   0          41s   10.244.36.82     k8s-node1   <none>           <none>
pod/nginx-deployment-5d9c9b97bb-p58lf   1/1     Running   0          41s   10.244.169.133   k8s-node2   <none>           <none>
pod/nginx-deployment-5d9c9b97bb-sm9zz   1/1     Running   0          41s   10.244.36.83     k8s-node1   <none>           <none>

注：查看deployment控制的rs和pod，發現rs是在deployment之后加了一段字符串，而pod是在rs之后加了一段字符串

即：deployment管理replicaset，replicaset管理pod。所以deployment比replicaset的功能更強大

 

3.deployment擴縮容

Deployment擴容縮容的本質其實就是改變ReplicaSet的數量來控制Pod的數量，增加就是擴容，縮小就是縮容。

• 方式一：kubectl scale deploy deploy名稱 --replicas=pod數量 -n 命名空間
• 方式二：kubectl edit deploy deploy名字 -n 命名空間

注：以上兩種方式均可以實現擴縮容，根據實際情況選擇即可

1）擴容示例：假設我們要將nginx從3個pod擴展到5個pod

[root@k8s-master yaml]# kubectl scale deploy nginx-deployment --replicas=5 -n default
deployment.apps/nginx-deployment scaled
[root@k8s-master yaml]# kubectl get deploy,rs,po
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment   5/5     5            5           19m

NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-5d9c9b97bb   5         5         5       19m

NAME                                    READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-5d9c9b97bb-4p2hx   1/1     Running   0          19m
pod/nginx-deployment-5d9c9b97bb-bjnbs   1/1     Running   0          29s
pod/nginx-deployment-5d9c9b97bb-p58lf   1/1     Running   0          19m
pod/nginx-deployment-5d9c9b97bb-sm9zz   1/1     Running   0          19m
pod/nginx-deployment-5d9c9b97bb-x92nj   1/1     Running   0          29s

 

 

2）縮容示例：假設我們將nginx從5個縮容到3個

[root@k8s-master yaml]# kubectl edit deploy nginx-deployment -n default
deployment.apps/nginx-deployment edited
#找到replicas，將其數量改為3
spec:
  progressDeadlineSeconds: 600
  replicas: 3
[root@k8s-master yaml]# kubectl get deploy,rs,po
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment   3/3     3            3           29m

NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-5d9c9b97bb   3         3         3       29m

NAME                                    READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-5d9c9b97bb-4p2hx   1/1     Running   0          29m
pod/nginx-deployment-5d9c9b97bb-bjnbs   1/1     Running   0          9m47s
pod/nginx-deployment-5d9c9b97bb-p58lf   1/1     Running   0          29m

 

 

4.deployment更新和回滾

deployment支持兩種鏡像更新策略：重建更新和滾動更新（默認），可以通過strategy選項進行配置

strategy：指定新的pod替換舊的pod的策略，支持兩個屬性：
  type：指定策略類型，支持兩種策略
    Recreate：在創建出新的pod之前會先殺掉所有已存在的pod
    RollingUpdate：滾動更新，就是殺死一部分，就啟動一部分，在更新過程中，存在兩個版本pod
  rollingUpdate：當type為RollingUpdate時生效，用於為RollingUpdate設置參數，支持兩個屬性
    maxUnavailable：用來指定在升級過程中不可用pod的最大數量，默認為25%
    maxSurge：用來指定在升級過程中可以超過期望的pod的最大數量，默認為25%

 

1）重建更新

編輯pc-deployment.yaml，在spec節點下添加更新策略

spec:
  strategy:  #策略
    type: Recreate  #重建更新策略

創建deploy進行驗證

#首先記錄原本的pod名
[root@k8s-master yaml]# kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-5d9c9b97bb-4p2hx   1/1     Running   0          40m
nginx-deployment-5d9c9b97bb-bjnbs   1/1     Running   0          21m
nginx-deployment-5d9c9b97bb-p58lf   1/1     Running   0          40m

#更改pod鏡像
[root@k8s-master yaml]# kubectl set image deploy nginx-deployment nginx=nginx:1.17.2
deployment.apps/nginx-deployment image updated

#再次查看鏡像(先是中斷rs控制器，再是拉取nginx新鏡像，最后根據新鏡像創建pod)
[root@k8s-master yaml]# kubectl get pods
NAME                                READY   STATUS        RESTARTS   AGE
nginx-deployment-5d9c9b97bb-4p2hx   0/1     Terminating   0          42m
[root@k8s-master yaml]# kubectl get pods
NAME                                READY   STATUS              RESTARTS   AGE
nginx-deployment-7c7477c7ff-5xmxl   0/1     ContainerCreating   0          0s
nginx-deployment-7c7477c7ff-xjdcg   0/1     ContainerCreating   0          0s
nginx-deployment-7c7477c7ff-xtxh7   0/1     ContainerCreating   0          0s
[root@k8s-master yaml]# kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-7c7477c7ff-5xmxl   1/1     Running   0          63s
nginx-deployment-7c7477c7ff-xjdcg   1/1     Running   0          63s
nginx-deployment-7c7477c7ff-xtxh7   1/1     Running   0          63s

 注：Recreate 的升級策略就是完全刪除再重建，這樣會導致服務一段時間不可用

 

 

2）滾動更新

編輯pc-deployment.yaml，在spec節點下添加滾動更新策略（也可以把strategy去掉，因為默認滾動更新策略）

strategy:
  type: RollingUpdate #滾動更新策略
  rollingUpdate:
    maxUnavailable: 25%  #用來指定在升級過程中不可用pod的最大數量，默認為25%
    maxSurge: 25% #用來指定在升級過程中可以超過期望的pod的最大數量，默認為25%

創建deploy進行驗證

滾動更新前(nginx為1.17.2)
[root@k8s-master yaml]# kubectl get deploy,rs,pod -o wide
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES         SELECTOR
deployment.apps/nginx-deployment   3/3     3            3           6m4s   nginx        nginx:1.17.2   app=nginx-pod

NAME                                          DESIRED   CURRENT   READY   AGE    CONTAINERS   IMAGES         SELECTOR
replicaset.apps/nginx-deployment-5d9c9b97bb   0         0         0       6m4s   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
replicaset.apps/nginx-deployment-7c7477c7ff   3         3         3       87s    nginx        nginx:1.17.2   app=nginx-pod,pod-template-hash=7c7477c7ff

NAME                                    READY   STATUS    RESTARTS   AGE   IP               NODE        NOMINATED NODE   READINESS GATES
pod/nginx-deployment-7c7477c7ff-769lc   1/1     Running   0          84s   10.244.36.94     k8s-node1   <none>           <none>
pod/nginx-deployment-7c7477c7ff-9jvdj   1/1     Running   0          87s   10.244.36.93     k8s-node1   <none>           <none>
pod/nginx-deployment-7c7477c7ff-m9b2r   1/1     Running   0          85s   10.244.169.139   k8s-node2   <none>           <none> 更新鏡像
[root@k8s-master yaml]# kubectl set image deploy nginx-deployment nginx=nginx:1.17.3
deployment.apps/nginx-deployment image updated
[root@k8s-master yaml]# kubectl get deploy,rs,pod -o wide
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES         SELECTOR
deployment.apps/nginx-deployment   3/3     3            3           8m43s   nginx        nginx:1.17.3   app=nginx-pod

NAME                                          DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES         SELECTOR
replicaset.apps/nginx-deployment-5d9c9b97bb   0         0         0       8m43s   nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
replicaset.apps/nginx-deployment-76fd8c7f84   3         3         2       3s      nginx        nginx:1.17.3   app=nginx-pod,pod-template-hash=76fd8c7f84
replicaset.apps/nginx-deployment-7c7477c7ff   1         1         1       4m6s    nginx        nginx:1.17.2   app=nginx-pod,pod-template-hash=7c7477c7ff

NAME                                    READY   STATUS              RESTARTS   AGE    IP               NODE        NOMINATED NODE   READINESS GATES
pod/nginx-deployment-76fd8c7f84-2ttfm   1/1     Running             0          2s     10.244.169.140   k8s-node2   <none>           <none>
pod/nginx-deployment-76fd8c7f84-4g5wq   0/1     ContainerCreating   0          1s     <none>           k8s-node1   <none>           <none>
pod/nginx-deployment-76fd8c7f84-694sl   1/1     Running             0          3s     10.244.36.95     k8s-node1   <none>           <none>
pod/nginx-deployment-7c7477c7ff-769lc   0/1     Terminating         0          4m3s   10.244.36.94     k8s-node1   <none>           <none>
pod/nginx-deployment-7c7477c7ff-9jvdj   1/1     Running             0          4m6s   10.244.36.93     k8s-node1   <none>           <none>
pod/nginx-deployment-7c7477c7ff-m9b2r   1/1     Terminating         0          4m4s   10.244.169.139   k8s-node2   <none>           <none> 查看更新后鏡像版本（nginx為1.17.3）
[root@k8s-master yaml]# kubectl get deploy,rs,pod -o wide
NAME                               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
deployment.apps/nginx-deployment   3/3     3            3           10m   nginx        nginx:1.17.3   app=nginx-pod

NAME                                          DESIRED   CURRENT   READY   AGE    CONTAINERS   IMAGES         SELECTOR
replicaset.apps/nginx-deployment-5d9c9b97bb   0         0         0       10m    nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=5d9c9b97bb
replicaset.apps/nginx-deployment-76fd8c7f84   3         3         3       118s   nginx        nginx:1.17.3   app=nginx-pod,pod-template-hash=76fd8c7f84
replicaset.apps/nginx-deployment-7c7477c7ff   0         0         0       6m1s   nginx        nginx:1.17.2   app=nginx-pod,pod-template-hash=7c7477c7ff

NAME                                    READY   STATUS    RESTARTS   AGE    IP               NODE        NOMINATED NODE   READINESS GATES
pod/nginx-deployment-76fd8c7f84-2ttfm   1/1     Running   0          117s   10.244.169.140   k8s-node2   <none>           <none>
pod/nginx-deployment-76fd8c7f84-4g5wq   1/1     Running   0          116s   10.244.36.96     k8s-node1   <none>           <none>
pod/nginx-deployment-76fd8c7f84-694sl   1/1     Running   0          118s   10.244.36.95     k8s-node1   <none>           <none>

 

 

3）滾動更新的過程

 

 

 

5.deployment回滾

deployment支持版本升級過程中的暫停，繼續功能以及版本回退等諸多功能，下面具體來看

kubectl rollout：版本升級相關功能，支持下面的選項：

• status：顯示當前升級狀態
• history：顯示升級歷史記錄
• pause：暫停版本升級過程
• resume：繼續已經暫停的版本升級過程
• restart：重啟版本升級過程
• undo：回滾到上一級版本（可以使用--to-revision回滾到指定版本）

#當前nginx版本
[root@k8s-master yaml]# kubectl get deploy -o wide
NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
nginx-deployment   3/3     3            3           24m   nginx        nginx:1.17.3   app=nginx-pod


#查看升級狀態
[root@k8s-master yaml]# kubectl rollout status deploy nginx-deployment
deployment "nginx-deployment" successfully rolled out

#查看升級歷史
[root@k8s-master yaml]# kubectl rollout history deploy nginx-deployment
deployment.apps/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>
3         <none> #查看版本詳情
[root@k8s-master yaml]# kubectl rollout history deployment nginx-deployment --revision=2
deployment.apps/nginx-deployment with revision #2
Pod Template:
  Labels:    app=nginx-pod
    pod-template-hash=7c7477c7ff
  Containers:
   nginx:
    Image:    nginx:1.17.2
    Port:    <none>
    Host Port:    <none>
    Environment:    <none>
    Mounts:    <none>
  Volumes:    <none> #版本回滾這里使用--to-revision=2回滾到2版本，如果省略這個選項，則會回退到上個版本
[root@k8s-master yaml]# kubectl rollout undo deployment nginx-deployment --to-revision=2
deployment.apps/nginx-deployment rolled back

#查看當前版本（nginx為1.17.2）說明回退成功
[root@k8s-master yaml]# kubectl get deployments -o wide
NAME               READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
nginx-deployment   3/3     3            3           27m   nginx        nginx:1.17.2   app=nginx-pod

 

 

 

6.金絲雀發布（灰度發布）

deployment支持更新過程中的控制，如"暫停（pause）"或"繼續（resume）"更新操作，觀察新服務實際運行狀況再決定操作

金絲雀發布（可以理解為灰度發布）：比如有一批新的pod資源創建完成后立即暫停更新過程，此時，僅存在一部分新版本的應用，主體部分還是舊的版本。然后，再篩選一小部分的用戶請求路由到新的pod應用，繼續觀察能否穩定地按期望的方式運行。確定沒問題之后再繼續完成余下的pod資源滾動更新，否則立即回滾更新操作。這就是所謂的金絲雀發布。

#更新deployment版本，並配置暫停deployment
[root@k8s-master yaml]# kubectl set image deploy nginx-deployment nginx=nginx:1.17.3 && kubectl rollout pause deploy nginx-deployment
deployment.apps/nginx-deployment image updated
deployment.apps/nginx-deployment paused


#查看rs，發現老版本rs沒有減少，新版本rs增加一個，狀態為更新中....
[root@k8s-master yaml]# kubectl get rs,deploy
NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-5d9c9b97bb   0         0         0       39m
replicaset.apps/nginx-deployment-76fd8c7f84   1         1         1       30m
replicaset.apps/nginx-deployment-7c7477c7ff   3         3         3       34m

NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment   4/3     1            4           39m
[root@k8s-master yaml]# kubectl rollout status deployment nginx-deployment 
Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 3 new replicas have been updated...


#繼續deploy的更新
[root@k8s-master yaml]# kubectl rollout resume deployment nginx-deployment 
deployment.apps/nginx-deployment resumed
[root@k8s-master yaml]# kubectl rollout status deployment nginx-deployment 
Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "nginx-deployment" rollout to finish: 1 old replicas are pending termination...
deployment "nginx-deployment" successfully rolled out


#查看rs更新結果，發現老版本均停止，新版本已經創建好
[root@k8s-master yaml]# kubectl get rs,deploy
NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-5d9c9b97bb   0         0         0       41m
replicaset.apps/nginx-deployment-76fd8c7f84   3         3         3       32m
replicaset.apps/nginx-deployment-7c7477c7ff   0         0         0       36m

NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment   3/3     3            3           41m