k8s 使用篇 - deployment

時間 2019-11-12

標籤 k8s 使用 deployment 简体版

原文原文鏈接

Deployment管理Pods和ReplicaSets，提供聲明式更新。和老的ReplicationController（命令式管理）對應，發展趨勢是取代老的，因此後面也不會起文章單獨討論ReplicationController了。node

但由Deployment-controller管理的Pods和ReplicaSets最好自始至終都由Deployment-controller管理，最好不要手動去管理，以避免發生衝突。nginx

建立Deployment

以下一個Deployment的配置（nginx-deployment.yaml），建立一個ReplicaSet包含3個nginx Podsdocker

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:1.7.9
        ports:
        - containerPort: 80

apiVersion這裏爲apps/v1，若是是1.9以前的版本爲extensions/v1beta1
replicas:3 起3個replicated Pods
selector指明哪一個pod被管理，這裏咱們指定了label（app:nginx）
template: spec 指明瞭運行一個容器nginx（以nginx:1.7.9爲鏡像）
開放80端口給container，以使container之間能發送和接收流量

注意這裏定義name 或 label 時不要和其餘的重複，k8s不會檢查這個，須要人工本身確認api

要建立此部署，執行下面的命令（在這以前咱們提早下好nginx相關的鏡像，docker pull nginx:1.7.9）瀏覽器

[root@master yaml]# kubectl create -f nginx-deployment.yaml --record
deployment "nginx-deployment" created

--record會記錄操做歷史，以便於後面回滾操做

查看deploymentsbash

[root@master yaml]# kubectl get deployments
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3         0         0            0           1s

NAME：在集羣中的部署名稱
DESIRED：顯示配置裏定義的副本數量，這是應該達到的副本數量
CURRENT：當前正在運行的副本數量
UP-TO-DATE：更新到當前所需狀態的副本數量
AVAILABLE：可供使用的副本數量
AEG：顯示app存活的時間

經過下面語句可查追蹤部署狀況session

[root@master ~]# kubectl rollout status deployment/nginx-deployment
deployment "nginx-deployment" successfully rolled out
# 這是部署完成的狀態

# 未完成的會顯示當前部署哪一步了
[root@master ~]# kubectl rollout status deployment/nginx-deployment
Waiting for rollout to finish: 2 out of 3 new replicas have been updated...
deployment "nginx-deployment" successfully rolled out

過一會咱們再查看，就全app

[root@master ~]# kubectl get deployments
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3         3         3            3           51s

這裏注意若是定義了.spec.minReadySeconds，那麼必須通過定義的時間纔會達到AVAILABLE 狀態編輯器

經過下面的命令查看Deployment建立的ReplicaSet（rs）ide

[root@master ~]# kubectl get rs
NAME                          DESIRED   CURRENT   READY     AGE
nginx-deployment-6c54bd5869   3         3         3         56m

注意ReplicaSet的名稱格式爲[DEPLOYMENT-NAME]-[POD-TEMPLATE-HASH-VALUE]，後面的hash值是由Deployment自動建立的

查看Pods

[root@master ~]# kubectl get pods --show-labels
NAME                                READY     STATUS    RESTARTS   AGE       LABELS
nginx-deployment-6c54bd5869-9brqp   1/1       Running   0          58m       app=nginx,pod-template-hash=2710681425
nginx-deployment-6c54bd5869-dkmgh   1/1       Running   0          58m       app=nginx,pod-template-hash=2710681425
nginx-deployment-6c54bd5869-vzsht   1/1       Running   0          58m       app=nginx,pod-template-hash=2710681425

建立的ReplicaSet 會確保時刻有3個nginx Pods的副本在運行

更新Deployment

假設咱們想把nginx從1.7.9更新到1.9.1，有如下3種方式

1. 直接set命令設置變動的部分

$ kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
deployment "nginx-deployment" image updated

以上命令會自動回滾更改Pods，即中止必定量的老的，新建新的，直到來的終止完，新的啓動完

經過describe便可查看全部的細節

[root@master yaml]# kubectl describe deployment/nginx-deployment
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Thu, 15 Mar 2018 02:51:06 -0400
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision=2
                        kubernetes.io/change-cause=kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
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:1.9.1
    Port:         80/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-5964dfd755 (3/3 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled up replica set nginx-deployment-5964dfd755 to 1
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled down replica set nginx-deployment-6c54bd5869 to 2
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled up replica set nginx-deployment-5964dfd755 to 2
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled down replica set nginx-deployment-6c54bd5869 to 1
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled up replica set nginx-deployment-5964dfd755 to 3
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled down replica set nginx-deployment-6c54bd5869 to 0

可見image已經變了
另外Events可查看滾動更新的過程
另外上面的說的中止和新建的比例在這裏體現RollingUpdateStrategy: 25% max unavailable, 25% max surge，25% max unavailable確保在更新時只有部分會關閉（這裏是pod數的25%會關閉）。25% max surge確保建立新的pod也在必定比例上（這裏默認也是25%）

2. 經過直接修改線上的配置也可直接修改

kubectl edit deployment/nginx-deployment

會打開一個編輯器，修改指定的部分便可，這裏是.spec.template.spec.containers[0].image

3. 修改yaml文件，經過apply從新部署

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

但這裏有個警告: 也就是apply方式更新的資源應該是由kubectl create 加--save-config參數建立的或由apply建立的（apply當資源不存在時會建立）

這時咱們查看rs，會顯示新起了一個rs並將副本擴到3個，舊的rs都縮減爲0

[root@master yaml]# kubectl get rs
NAME                          DESIRED   CURRENT   READY     AGE
nginx-deployment-5964dfd755   3         3         3         21m
nginx-deployment-6c54bd5869   0         0         0         1h

回滾Deployment

有時須要回滾的操做，好比更新錯誤，手誤等一系列問題

好比上面的操做更新到1.9.1時，寫錯了，寫成1.91了

[root@master yaml]# kubectl set image deployment/nginx-deployment nginx=nginx:1.91
deployment "nginx-deployment" image updated

追蹤狀態

[root@master yaml]# kubectl rollout status deployments nginx-deployment
Waiting for rollout to finish: 1 out of 3 new replicas have been updated...

可見卡住不動了， Ctrl+C終止，查看rs以下

[root@master yaml]# kubectl get rs
NAME                          DESIRED   CURRENT   READY     AGE
nginx-deployment-5964dfd755   3         3         3         40m
nginx-deployment-5d5cfdbd5f   1         1         0         1m
nginx-deployment-6c54bd5869   0         0         0         2h

新的rs只啓動了Pod但沒有處於READY狀態

查看Pods

[root@master yaml]# kubectl get pods
NAME                                READY     STATUS             RESTARTS   AGE
nginx-deployment-5964dfd755-8z8b7   1/1       Running            0          27m
nginx-deployment-5964dfd755-bnznj   1/1       Running            0          27m
nginx-deployment-5964dfd755-pt54q   1/1       Running            0          27m
nginx-deployment-5d5cfdbd5f-srdcc   0/1       ImagePullBackOff   0          2m

可發現ImagePullBackOff，實際就是鏡像不存在

要修復這個，咱們就須要rollback到前一個ok的版本

查看操做歷史

[root@master yaml]# kubectl rollout history deployment/nginx-deployment
deployments "nginx-deployment"
REVISION    CHANGE-CAUSE
1           kubectl create -f docs/user-guide/nginx-deployment.yaml --record
2           kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
3           kubectl set image deployment/nginx-deployment nginx=nginx:1.91

要查看每一個版本的詳細狀況，指定--revision

[root@master yaml]# kubectl rollout history deployment/nginx-deployment --revision=2
deployments "nginx-deployment" with revision #2
Pod Template:
  Labels:       app=nginx
        pod-template-hash=2710681425
  Annotations:  kubernetes.io/change-cause=kubectl edit deployment/nginx-deployment
  Containers:
   nginx:
    Image:      nginx:1.9.1
    Port:       80/TCP
    Environment:        <none>
    Mounts:     <none>
  Volumes:      <none>

接下來進行回滾的操做

不指定版本，默認回滾到上一個版本

[root@master yaml]# kubectl rollout undo deployment/nginx-deployment
deployment "nginx-deployment" rolled back

指定版本，經過--to-revision指定

[root@master yaml]# kubectl rollout undo deployment/nginx-deployment --to-revision=2
deployment "nginx-deployment" rolled back

查看

kubectl describe deployment/nginx-deployment

....略

Events:
  FirstSeen LastSeen    Count   From                    SubobjectPath   Type        Reason              Message
  --------- --------    -----   ----                    -------------   --------    ------              -------
  30m       30m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-2035384211 to 3
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-1564180365 to 1
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled down replica set nginx-deployment-2035384211 to 2
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-1564180365 to 2
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled down replica set nginx-deployment-2035384211 to 0
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-3066724191 to 2
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-3066724191 to 1
  29m       29m         1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled down replica set nginx-deployment-1564180365 to 2
  2m        2m          1       {deployment-controller }                Normal      ScalingReplicaSet   Scaled down replica set nginx-deployment-3066724191 to 0
  2m        2m          1       {deployment-controller }                Normal      DeploymentRollback  Rolled back deployment "nginx-deployment" to revision 2
  29m       2m          2       {deployment-controller }                Normal      ScalingReplicaSet   Scaled up replica set nginx-deployment-1564180365 to 3

可看到有DeploymentRollback Reason的事件

擴展Deployment

可經過以下的命令進行擴展

[root@master yaml]# kubectl scale deployment nginx-deployment --replicas=5
deployment "nginx-deployment" scaled

查看Pods

[root@master yaml]# kubectl get pods
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-5964dfd755-8z8b7   1/1       Running   0          41m
nginx-deployment-5964dfd755-bhm2s   1/1       Running   0          1m
nginx-deployment-5964dfd755-bnznj   1/1       Running   0          41m
nginx-deployment-5964dfd755-cftfj   1/1       Running   0          6s
nginx-deployment-5964dfd755-pt54q   1/1       Running   0          41m

可見已擴展到5個

使用autoscale還可設置自動水平擴展（hpa），可根據機器負載之類的信息自動擴展或縮減，這個後面細講

$ kubectl autoscale deployment nginx-deployment --min=10 --max=15 --cpu-percent=80
deployment "nginx-deployment" autoscaled

暫停和恢復Deployment

有時須要修改多個部分，而不是上面的只修改image，這樣的話每次改完都自動部署，顯然很差，經過pause便可暫停Deployment，更改完了，經過resume便可恢復部署

暫停

[root@master yaml]# kubectl rollout pause deployment/nginx-deployment
deployment "nginx-deployment" paused

修改

[root@master yaml]# kubectl set image deploy/nginx-deployment nginx=nginx:1.7.9
deployment "nginx-deployment" image updated

查看Pods

[root@master yaml]# kubectl get pods
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-5964dfd755-8z8b7   1/1       Running   0          57m
nginx-deployment-5964dfd755-bhm2s   1/1       Running   0          17m
nginx-deployment-5964dfd755-bnznj   1/1       Running   0          57m
nginx-deployment-5964dfd755-cftfj   1/1       Running   0          16m
nginx-deployment-5964dfd755-pt54q   1/1       Running   0          57m

注意後面的AGE仍是以前的Pod，這裏就不會自動更新了

恢復

[root@master yaml]# kubectl rollout resume deploy/nginx-deployment
deployment "nginx-deployment" resumed

這時再查看Pods

[root@master yaml]# kubectl get pods
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-6c54bd5869-htjxz   1/1       Running   0          25s
nginx-deployment-6c54bd5869-lj288   1/1       Running   0          30s
nginx-deployment-6c54bd5869-nt8lt   1/1       Running   0          30s
nginx-deployment-6c54bd5869-svqz6   1/1       Running   0          29s
nginx-deployment-6c54bd5869-zq8tl   1/1       Running   0          25s

可見已經更新部署了

內部Deployment部分大概就講完了，下面把nginx服務暴露到外面

刪除Deployment

[root@master yaml]# kubectl delete -f nginx-deployment.yaml 
deployment "nginx-deployment" deleted

部署service

服務的暴露須要Service，它是Pod的抽象代理（具體機制見這裏）。見nginx-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: NodePort
  sessionAffinity: ClientIP
  selector:
    app: nginx
  ports:
    - port: 80
      nodePort: 30080

kind：Service表明是一個服務
type：NodePort k8s將會在每一個Node上打開一個端口而且每一個Node的端口都是同樣的，經過<NodeIP>:NodePort的方式Kubernetes集羣外部的程序能夠訪問Service。
selector：哪一個服務須要暴露
port：service暴露的端口
TargetPort：pod的端口
nodePort：對外暴露的端口，不設置會默認分配，範圍：30000－32767
轉發邏輯是：
<NodeIP>:<nodeport> => <ServiceVIP>:<port>=> <PodIP>:<targetport>

部署service服務：

[root@master yaml]# kubectl create -f nginx-service.yaml 
service "nginx-service" created

可看到啓動了一個svc

NAME                TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes      ClusterIP   10.96.0.1       <none>        443/TCP        1d
svc/nginx-service   NodePort    10.101.86.235   <none>        80:30080/TCP   4m

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