9.1 k8s pod版本更新流程及命令行實現升級與回滾

本文轉載自查看原文 2021-10-29 21:02 1112

1.創建 Deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# vim nginx-deployment.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

在該例中：

創建名為 nginx-deployment（由 .metadata.name 字段標明）的 Deployment。
該 Deployment 創建三個（由 replicas 字段標明）Pod 副本。
selector 字段定義 Deployment 如何查找要管理的 Pods。在這里，你選擇在 Pod 模板中定義的標簽（app: nginx）, 在 API 版本 apps/v1 中，Deployment 標簽選擇算符在創建后是不可變的。

說明：

spec.selector.matchLabels 字段是 {key,value} 鍵值對映射。在 matchLabels 映射中的每個 {key,value} 映射等效於 matchExpressions 中的一個元素，即其 key 字段是 “key”，operator 為 “In”，values 數組僅包含 “value”。在 matchLabels 和 matchExpressions 中給出的所有條件都必須滿足才能匹配。

template 字段包含以下子字段：

Pod 被使用 labels 字段打上 app: nginx 標簽。
Pod 模板規約（即 .template.spec 字段）指示 Pods 運行一個 nginx 容器，該容器運行版本為 1.14.2 的 nginx Docker Hub鏡像。
創建一個容器並使用 name 字段將其命名為 nginx。

通過運行以下命令創建 Deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl apply -f nginx-deployment.yaml 
deployment.apps/nginx-deployment created

說明：你可以設置 --record 標志將所執行的命令寫入資源注解中。這對於以后的檢查是有用的。例如，要查看針對每個 Deployment 修訂版本所執行過的命令。

檢查 Deployment 是否已創建

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   0/3     3            0           9s

在檢查集群中的 Deployment 時，所顯示的字段有：

NAME 列出了集群中 Deployment 的名稱。
READY 顯示應用程序的可用的副本數。顯示的模式是“就緒個數/期望個數”。
UP-TO-DATE 顯示為了達到期望狀態已經更新的副本數。
AVAILABLE 顯示應用可供用戶使用的副本數。
AGE 顯示應用程序運行的時間。
請注意期望副本數是根據 .spec.replicas 字段設置 3。

幾秒鍾后再次運行 kubectl get deployments

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           45s

要查看 Deployment 創建的 ReplicaSet（rs）

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get rs 
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-66b6c48dd5   3         3         3       11m

ReplicaSet 輸出中包含以下字段：

NAME 列出名字空間中 ReplicaSet 的名稱；

DESIRED 顯示應用的期望副本個數，即在創建 Deployment 時所定義的值。此為期望狀態；
CURRENT 顯示當前運行狀態中的副本個數；
READY 顯示應用中有多少副本可以為用戶提供服務；
AGE 顯示應用已經運行的時間長度。
注意 ReplicaSet 的名稱始終被格式化為[Deployment名稱]-[隨機字符串]。其中的隨機字符串是使用 pod-template-hash 作為種子隨機生成的。

查看每個 Pod 自動生成的標簽

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get pods --show-labels
NAME                                READY   STATUS    RESTARTS   AGE   LABELS
nginx-deployment-66b6c48dd5-hdxlg   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-hnmgw   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-p28z2   1/1     Running   0          44m   app=nginx,pod-template-hash=66b6c48dd5

說明：

你必須在 Deployment 中指定適當的選擇算符和 Pod 模板標簽（在本例中為 app: nginx）。標簽或者選擇算符不要與其他控制器（包括其他 Deployment 和 StatefulSet）重疊。 Kubernetes 不會阻止你這樣做，但是如果多個控制器具有重疊的選擇算符，它們可能會發生沖突執行難以預料的操作。
Deployment 控制器將 pod-template-hash 標簽添加到 Deployment 所創建或收留的每個 ReplicaSet 。
此標簽可確保 Deployment 的子 ReplicaSets 不重疊。標簽是通過對 ReplicaSet 的 PodTemplate 進行哈希處理。所生成的哈希值被添加到 ReplicaSet 選擇算符、Pod 模板標簽，並存在於在 ReplicaSet 可能擁有的任何現有 Pod 中。

2.更新 Deployment

說明：

僅當 Deployment Pod 模板（即 .spec.template）發生改變時，例如模板的標簽或容器鏡像被更新，才會觸發 Deployment 上線。其他更新（如對 Deployment 執行擴縮容的操作）不會觸發上線動作。

更新nginx Pod的鏡像版本，比如從nginx:1.14.2升級到nginx:1.16.1

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record
deployment.apps/nginx-deployment image updated

監控更新過程

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout status deployment/nginx-deployment
Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 3 new replicas have been updated...
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

在上線成功后,查看deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deploy
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           72m

查看 Deployment控制的ReplicaSet

可以看出Deployment通過創建新的 ReplicaSet 並將其擴容到 3 個副本並將舊 ReplicaSet 縮容到 0 個副本完成了 Pod 的更新操作

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-559d658b74   3         3         3       5m
nginx-deployment-66b6c48dd5   0         0         0       74m

查看更新后的pod

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get pod --show-labels
NAME                                READY   STATUS    RESTARTS   AGE     LABELS
nginx-deployment-559d658b74-4npbn   1/1     Running   0          6m29s   app=nginx,pod-template-hash=559d658b74
nginx-deployment-559d658b74-4wqbp   1/1     Running   0          6m17s   app=nginx,pod-template-hash=559d658b74
nginx-deployment-559d658b74-9wrpj   1/1     Running   0          6m41s   app=nginx,pod-template-hash=559d658b74

說明：

Deployment 可確保在更新時僅關閉一定數量的 Pod。默認情況下，它確保至少所需 Pods 75% 處於運行狀態（最大不可用比例為 25%）。
Deployment 還確保僅所創建 Pod 數量只可能比期望 Pods 數高一點點。默認情況下，它可確保啟動的 Pod 個數比期望個數最多多出 25%（最大峰值 25%）。

獲取 Deployment 的更多信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl describe deployments
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Wed, 29 Sep 2021 16:01:55 +0800
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision: 2
                        kubernetes.io/change-cause: kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:1.16.1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-559d658b74 (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  9m11s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 1
  Normal  ScalingReplicaSet  8m59s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 2
  Normal  ScalingReplicaSet  8m59s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 2
  Normal  ScalingReplicaSet  8m47s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 1
  Normal  ScalingReplicaSet  8m47s  deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 3
  Normal  ScalingReplicaSet  8m25s  deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 0

3.回滾 Deployment

說明：

Deployment 被觸發上線時，系統就會創建 Deployment 的新的修訂版本。這意味着僅當 Deployment 的 Pod 模板（.spec.template）發生更改時，才會創建新修訂版本 -- 例如，模板的標簽或容器鏡像發生變化。其他更新，如 Deployment 的擴縮容操作不會創建 Deployment 修訂版本。這是為了方便同時執行手動縮放或自動縮放。換言之，當你回滾到較早的修訂版本時，只有 Deployment 的 Pod 模板部分會被回滾。

查看更新的歷史記錄

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout history deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true

查看某個版本的更詳細的更加記錄信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl rollout history deployment.v1.apps/nginx-deployment --revision=2
deployment.apps/nginx-deployment with revision #2
Pod Template:
  Labels:       app=nginx
        pod-template-hash=559d658b74
  Annotations:  kubernetes.io/change-cause: kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record=true
  Containers:
   nginx:
    Image:      nginx:1.16.1
    Port:       80/TCP
    Host Port:  0/TCP
    Environment:        <none>
    Mounts:     <none>
  Volumes:      <none>

回滾到之前的版本

kubectl rollout undo deployment.v1.apps/nginx-deployment --to-revision=1
deployment.apps/nginx-deployment rolled back

查看回滾后的deployment

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl get deployment nginx-deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           91m

查看deploymne的詳細信息

root@k8-deploy:~/k8s-yaml/controllers/deployments# kubectl describe deployment nginx-deployment
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Wed, 29 Sep 2021 16:01:55 +0800
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision: 3
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:1.14.2
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-66b6c48dd5 (3/3 replicas created)
Events:
  Type    Reason             Age                From                   Message
  ----    ------             ----               ----                   -------
  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 1
  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 2
  Normal  ScalingReplicaSet  22m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 2
  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 1
  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled up replica set nginx-deployment-559d658b74 to 3
  Normal  ScalingReplicaSet  21m                deployment-controller  Scaled down replica set nginx-deployment-66b6c48dd5 to 0
  Normal  ScalingReplicaSet  17s                deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 1
  Normal  ScalingReplicaSet  15s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 2
  Normal  ScalingReplicaSet  15s                deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 2
  Normal  ScalingReplicaSet  13s (x2 over 91m)  deployment-controller  Scaled up replica set nginx-deployment-66b6c48dd5 to 3
  Normal  ScalingReplicaSet  13s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 1
  Normal  ScalingReplicaSet  11s                deployment-controller  Scaled down replica set nginx-deployment-559d658b74 to 0

4.擴縮容Deployment

root@k8-deploy:~# kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
deployment.apps/nginx-deployment scaled

root@k8-deploy:~# kubectl get deploy
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   10/10   10           10          97m

root@k8-deploy:~# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-559d658b74   0         0         0       27m
nginx-deployment-66b6c48dd5   10        10        10      97m

root@k8-deploy:~# kubectl get pod -o wide --show-labels
NAME                                READY   STATUS    RESTARTS   AGE     IP               NODE           NOMINATED NODE   READINESS GATES   LABELS
nginx-deployment-66b6c48dd5-7tl82   1/1     Running   0          6m33s   10.100.112.5     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-b8wvd   1/1     Running   0          69s     10.100.172.196   192.168.2.17   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-cqmzm   1/1     Running   0          6m31s   10.100.112.6     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-h9bhf   1/1     Running   0          69s     10.100.224.71    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-jzhkt   1/1     Running   0          69s     10.100.224.72    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-kdvss   1/1     Running   0          6m29s   10.100.112.7     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-kxsvq   1/1     Running   0          69s     10.100.172.197   192.168.2.17   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-tlckf   1/1     Running   0          69s     10.100.112.8     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-wfvmh   1/1     Running   0          69s     10.100.224.73    192.168.2.18   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5
nginx-deployment-66b6c48dd5-zmsfm   1/1     Running   0          69s     10.100.112.9     192.168.2.19   <none>           <none>            app=nginx,pod-template-hash=66b6c48dd5

暫停、恢復 Deployment

你可以在觸發一個或多個更新之前暫停 Deployment，然后再恢復其執行。
這樣做使得你能夠在暫停和恢復執行之間應用多個修補程序，而不會觸發不必要的上線操作。

查看現有的deplymnet集群 rs

root@k8-deploy:~# kubectl get deployment
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3/3     3            3           4s
root@k8-deploy:~# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-66b6c48dd5   3         3         3       7s

執行暫停

root@k8-deploy:~# kubectl rollout pause deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment paused

對deploymnet執行多項修改中的一項，比如修改pod鏡像版本

root@k8-deploy:~# kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.17.10
deployment.apps/nginx-deployment image updated

在暫停期間對deploymnet的修改不會立即觸發更新

root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>

繼續對deploymnet鏡像修改，比如對pod使用的資源進行限制

root@k8-deploy:~# kubectl set resources deployment.v1.apps/nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi
deployment.apps/nginx-deployment resource requirements updated

# 此時deployment仍然不會觸發更新
root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none

恢復 Deployment 執行

root@k8-deploy:~# kubectl rollout resume deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment resumed

觀察新的 ReplicaSet 的創建過程，其中包含了所應用的所有更新

root@k8-deploy:~# kubectl get rs -w
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-66b6c48dd5   2         2         2       6m26s
nginx-deployment-fcfbff66c    2         2         1       6s
nginx-deployment-fcfbff66c    2         2         2       16s
nginx-deployment-66b6c48dd5   1         2         2       6m36s
nginx-deployment-fcfbff66c    3         2         2       16s
nginx-deployment-66b6c48dd5   1         2         2       6m36s
nginx-deployment-fcfbff66c    3         2         2       16s
nginx-deployment-fcfbff66c    3         3         2       16s
nginx-deployment-66b6c48dd5   1         1         1       6m36s
nginx-deployment-fcfbff66c    3         3         3       28s
nginx-deployment-66b6c48dd5   0         1         1       6m48s
nginx-deployment-66b6c48dd5   0         1         1       6m48s
nginx-deployment-66b6c48dd5   0         0         0       6m48s

root@k8-deploy:~# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-66b6c48dd5   0         0         0       7m55s
nginx-deployment-fcfbff66c    3         3         3       95s

root@k8-deploy:~# kubectl rollout history deployment.v1.apps/nginx-deployment
deployment.apps/nginx-deployment 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

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