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。java
備註: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。node
建立Deploymentnginx
以下一個Deployment的配置(nginx-deployment.yaml),建立一個ReplicaSet包含3個nginx Podsweb
apiVersion: apps/v1spring
kind: Deploymentdocker
metadata: 數據庫
name: nginx-deployment api
labels: 瀏覽器
app: nginxtomcat
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
備註: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
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)
[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deployments
[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
[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
[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
經過下面的命令查看Deployment建立的ReplicaSet(rs)
[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 ~]
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
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: 0RollingUpdateStrategy: 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 MinimumReplicas
Available 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
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
...............
可看到有DeploymentRollback Reason的事件
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
[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 s
ervice "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
瀏覽器測試
本文出自https://my.oschina.net/u/2306127/blog/1647246
maxSurge: 1 表示滾動升級時會先啓動1個pod
maxUnavailable: 1 表示滾動升級時容許的最大Unavailable的pod個數
因爲replicas爲3,則整個升級,pod個數在2-4個之間
k8s將會給應用發送SIGTERM信號,能夠用來正確、優雅地關閉應用,默認爲30秒。
若是須要更優雅地關閉,則可使用k8s提供的pre-stop lifecycle hook 的配置聲明,將會在發送SIGTERM以前執行。
livenessProbe是kubernetes認爲該pod是存活的,不存在則須要kill掉,而後再新啓動一個,以達到replicas指定的個數。
readinessProbe是kubernetes認爲該pod是啓動成功的,這裏根據每一個應用的特性,本身去判斷,能夠執行command,也能夠進行httpGet。好比對於使用java web服務的應用來講,並非簡單地說tomcat啓動成功就能夠對外提供服務的,還須要等待spring容器初始化,數據庫鏈接鏈接上等等。對於spring boot應用,默認的actuator帶有/health接口,能夠用來進行啓動成功的判斷。
其中readinessProbe.initialDelaySeconds能夠設置爲系統徹底啓動起來所需的最少時間,livenessProbe.initialDelaySeconds能夠設置爲系統徹底啓動起來所需的最大時間+若干秒。
參考使用kubernetes的deployment進行RollingUpdate
https://www.jianshu.com/p/6bc8e0ae65d1