K8s中RS和Deployment

時間 2020-06-24

標籤 k8s deployment 简体版

原文原文鏈接

什麼是ReplicaSet？

ReplicaSet是下一代複本控制器。ReplicaSet和 Replication Controller之間的惟一區別是如今的選擇器支持。Replication Controller只支持基於等式的selector（env=dev或environment!=qa），但ReplicaSet還支持新的，基於集合的selector（version in (v1.0, v2.0)或env notin (dev, qa)）。在試用時官方推薦ReplicaSet。html

大多數kubectl支持Replication Controller的命令也支持ReplicaSets。rolling-update命令有一個例外。若是您想要滾動更新功能，請考慮使用Deployments。此外， rolling-update命令是必須的，而Deployments是聲明式的，所以咱們建議經過rollout命令使用Deployments。node

雖然ReplicaSets能夠獨立使用，可是今天它主要被 Deployments 做爲協調pod建立，刪除和更新的機制。當您使用Deployments時，您沒必要擔憂管理他們建立的ReplicaSets。Deployments擁有並管理其ReplicaSets。linux

什麼時候使用ReplicaSet？

ReplicaSet可確保指定數量的pod「replicas」在任何設定的時間運行。然而，Deployments是一個更高層次的概念，它管理ReplicaSets，並提供對pod的聲明性更新以及許多其餘的功能。所以，咱們建議您使用Deployments而不是直接使用ReplicaSets，除非您須要自定義更新編排或根本不須要更新。nginx

這實際上意味着您可能永遠不須要操做ReplicaSet對象：直接使用Deployments並在規範部分定義應用程序。api

[root@k8s-master mnt]# cat rs.yaml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
        tier: frontend
    spec:
      containers:
      - name: myapp
        image: wangyanglinux/myapp:v1
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 80
[root@k8s-master mnt]#

[root@k8s-master mnt]# kubectl create -f rs.yaml
replicaset.apps/frontend created
[root@k8s-master mnt]# kubectl get pod
NAME             READY   STATUS    RESTARTS   AGE
frontend-4xs95   1/1     Running   0          12s
frontend-gd5th   1/1     Running   0          12s
frontend-tn9pn   1/1     Running   0          12s
[root@k8s-master mnt]# kubectl delete pod --all
pod "frontend-4xs95" deleted
pod "frontend-gd5th" deleted
pod "frontend-tn9pn" deleted
[root@k8s-master mnt]# kubectl get pod
NAME             READY   STATUS    RESTARTS   AGE
frontend-gh2w5   1/1     Running   0          3m58s
frontend-rd9pl   1/1     Running   0          3m58s
frontend-xg845   1/1     Running   0          3m58s
[root@k8s-master mnt]# kubectl get pod --show-labels
NAME             READY   STATUS    RESTARTS   AGE     LABELS
frontend-gh2w5   1/1     Running   0          4m38s   tier=frontend
frontend-rd9pl   1/1     Running   0          4m38s   tier=frontend
frontend-xg845   1/1     Running   0          4m38s   tier=frontend
[root@k8s-master mnt]# kubectl get pod --show-labels
NAME             READY   STATUS    RESTARTS   AGE     LABELS
frontend-btqh8   1/1     Running   0          3s      tier=frontend
frontend-gh2w5   1/1     Running   0          7m43s   tier=frontend
frontend-rd9pl   1/1     Running   0          7m43s   tier=frontend1
frontend-xg845   1/1     Running   0          7m43s   tier=frontend
[root@k8s-master mnt]# kubectl delete pod --all
pod "frontend-btqh8" deleted
pod "frontend-gh2w5" deleted
pod "frontend-rd9pl" deleted
pod "frontend-xg845" deleted
[root@k8s-master mnt]# kubectl get pod --show-labels
NAME             READY   STATUS    RESTARTS   AGE   LABELS
frontend-mnmlm   1/1     Running   0          28s   tier=frontend
frontend-x8rcp   1/1     Running   0          27s   tier=frontend
frontend-zqs4n   1/1     Running   0          28s   tier=frontend
[root@k8s-master mnt]# kubectl delete -f rs.yaml
replicaset.apps "frontend" deleted
[root@k8s-master mnt]# kubectl get pod --show-labels
NAME             READY   STATUS        RESTARTS   AGE   LABELS
frontend-mnmlm   0/1     Terminating   0          47s   tier=frontend
frontend-x8rcp   0/1     Terminating   0          46s   tier=frontend
frontend-zqs4n   0/1     Terminating   0          47s   tier=frontend

Deployment是什麼？

Deployment爲Pod和Replica Set（下一代Replication Controller）提供聲明式更新。app

你只須要在Deployment中描述你想要的目標狀態是什麼，Deployment controller就會幫你將Pod和Replica Set的實際狀態改變到你的目標狀態。你能夠定義一個全新的Deployment，也能夠建立一個新的替換舊的Deployment。frontend

一個典型的用例以下：curl

使用Deployment來建立ReplicaSet。ReplicaSet在後臺建立pod。檢查啓動狀態，看它是成功仍是失敗。
而後，經過更新Deployment的PodTemplateSpec字段來聲明Pod的新狀態。這會建立一個新的ReplicaSet，Deployment會按照控制的速率將pod從舊的ReplicaSet移動到新的ReplicaSet中。
若是當前狀態不穩定，回滾到以前的Deployment revision。每次回滾都會更新Deployment的revision。
擴容Deployment以知足更高的負載。
暫停Deployment來應用PodTemplateSpec的多個修復，而後恢復上線。
根據Deployment 的狀態判斷上線是否hang住了。
清除舊的沒必要要的ReplicaSet。

代碼展現：ide

[root@k8s-master mnt]# cat deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: wangyanglinux/myapp:v1
        ports:
        - containerPort: 80
[root@k8s-master mnt]#

下面的代碼包括了擴容和回退和更新。url

[root@k8s-master mnt]# kubectl apply -f deployment.yaml --record
deployment.apps/nginx-deployment created
[root@k8s-master mnt]# kubectl get pod
NAME                                READY   STATUS              RESTARTS   AGE
nginx-deployment-64ddb75745-fkfxl   0/1     ContainerCreating   0          1s
nginx-deployment-64ddb75745-slcwp   0/1     ContainerCreating   0          1s
nginx-deployment-64ddb75745-vwnqw   0/1     ContainerCreating   0          1s
[root@k8s-master mnt]# kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-64ddb75745-fkfxl   1/1     Running   0          55s
nginx-deployment-64ddb75745-slcwp   1/1     Running   0          55s
nginx-deployment-64ddb75745-vwnqw   1/1     Running   0          55s
[root@k8s-master mnt]# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-64ddb75745   3         3         3       65s
[root@k8s-master mnt]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE     IP           NODE         NOMINATED NODE   READINESS GATES
nginx-deployment-64ddb75745-fkfxl   1/1     Running   0          2m45s   10.244.2.6   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-slcwp   1/1     Running   0          2m45s   10.244.1.9   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-vwnqw   1/1     Running   0          2m45s   10.244.1.8   k8s-node02   <none>           <none>
[root@k8s-master mnt]# curl 10.244.2.6
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
[root@k8s-master mnt]# kubectl scale deployment nginx-deployment --replicas 10
deployment.apps/nginx-deployment scaled
[root@k8s-master mnt]# kubectl get pod -o wide
NAME                                READY   STATUS              RESTARTS   AGE     IP           NODE         NOMINATED NODE   READINESS GATES
nginx-deployment-64ddb75745-9c55m   0/1     ContainerCreating   0          3s      <none>       k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-9gs9v   0/1     ContainerCreating   0          3s      <none>       k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-fkfxl   1/1     Running             0          4m10s   10.244.2.6   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-nbl92   0/1     ContainerCreating   0          3s      <none>       k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-p4f2z   0/1     ContainerCreating   0          3s      <none>       k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-qtmhl   0/1     ContainerCreating   0          3s      <none>       k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-rgcsl   0/1     ContainerCreating   0          3s      <none>       k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-slcwp   1/1     Running             0          4m10s   10.244.1.9   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-vwnqw   1/1     Running             0          4m10s   10.244.1.8   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-zzmsn   0/1     ContainerCreating   0          3s      <none>       k8s-node01   <none>           <none>
[root@k8s-master mnt]# kubectl describe deployment
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Fri, 20 Dec 2019 15:10:03 +0800
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1
                        kubectl.kubernetes.io/last-applied-configuration:
                          {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{"kubernetes.io/change-cause":"kubectl apply --filename=de     ployment.y...
                        kubernetes.io/change-cause: kubectl apply --filename=deployment.yaml --record=true
Selector:               app=nginx
Replicas:               10 desired | 10 updated | 10 total | 10 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        wangyanglinux/myapp:v1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Progressing    True    NewReplicaSetAvailable
  Available      True    MinimumReplicasAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-64ddb75745 (10/10 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  11m    deployment-controller  Scaled up replica set nginx-deployment-64ddb75745 to 3
  Normal  ScalingReplicaSet  7m28s  deployment-controller  Scaled up replica set nginx-deployment-64ddb75745 to 10
[root@k8s-master mnt]# kubectl rollout history deployment/nginx-deployment
deployment.apps/nginx-deployment
REVISION  CHANGE-CAUSE
1         kubectl apply --filename=deployment.yaml --record=true

[root@k8s-master mnt]# kubectl set image deployment/nginx-deployment nginx=wangyanglinux/myapp:v2
deployment.apps/nginx-deployment image updated
[root@k8s-master mnt]# kubectl get pod -o wide
NAME                                READY   STATUS        RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
nginx-deployment-64ddb75745-rgcsl   0/1     Terminating   0          30m   10.244.1.12   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-slcwp   0/1     Terminating   0          35m   10.244.1.9    k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-2qwdf   1/1     Running       0          23s   10.244.2.12   k8s-node01   <none>           <none>
nginx-deployment-6bd7755b5b-2tpzn   1/1     Running       0          23s   10.244.2.11   k8s-node01   <none>           <none>
nginx-deployment-6bd7755b5b-5d2fn   1/1     Running       0          23s   10.244.1.14   k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-87vdh   1/1     Running       0          23s   10.244.2.13   k8s-node01   <none>           <none>
nginx-deployment-6bd7755b5b-fl56p   1/1     Running       0          14s   10.244.1.16   k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-gpz9q   1/1     Running       0          12s   10.244.1.17   k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-hhfbn   1/1     Running       0          11s   10.244.2.15   k8s-node01   <none>           <none>
nginx-deployment-6bd7755b5b-k5rm7   1/1     Running       0          23s   10.244.1.13   k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-skh7w   1/1     Running       0          14s   10.244.1.15   k8s-node02   <none>           <none>
nginx-deployment-6bd7755b5b-t494q   1/1     Running       0          13s   10.244.2.14   k8s-node01   <none>           <none>
[root@k8s-master mnt]# curl 10.244.1.14
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[root@k8s-master mnt]# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-64ddb75745   0         0         0       35m
nginx-deployment-6bd7755b5b   10        10        10      64s
[root@k8s-master mnt]# kubectl rollout undo deployment/nginx-deployment
deployment.apps/nginx-deployment rolled back
[root@k8s-master mnt]# kubectl get pod
NAME                                READY   STATUS              RESTARTS   AGE
nginx-deployment-64ddb75745-48d5d   1/1     Running             0          11s
nginx-deployment-64ddb75745-4ctzd   1/1     Running             0          13s
nginx-deployment-64ddb75745-8g7f9   1/1     Running             0          13s
nginx-deployment-64ddb75745-bnwlj   1/1     Running             0          9s
nginx-deployment-64ddb75745-gq29d   1/1     Running             0          13s
nginx-deployment-64ddb75745-rp52v   1/1     Running             0          13s
nginx-deployment-64ddb75745-sxch9   1/1     Running             0          10s
nginx-deployment-64ddb75745-tt8tp   0/1     ContainerCreating   0          5s
nginx-deployment-64ddb75745-vtx8w   1/1     Running             0          13s
nginx-deployment-64ddb75745-zr8c7   1/1     Running             0          7s
nginx-deployment-6bd7755b5b-2qwdf   1/1     Terminating         0          3m14s
nginx-deployment-6bd7755b5b-2tpzn   1/1     Terminating         0          3m14s
nginx-deployment-6bd7755b5b-87vdh   1/1     Terminating         0          3m14s
[root@k8s-master mnt]# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-64ddb75745   10        10        10      38m
nginx-deployment-6bd7755b5b   0         0         0       3m29s
[root@k8s-master mnt]# kubectl get pod -o wide
NAME                                READY   STATUS    RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
nginx-deployment-64ddb75745-48d5d   1/1     Running   0          43s   10.244.2.18   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-4ctzd   1/1     Running   0          45s   10.244.1.18   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-8g7f9   1/1     Running   0          45s   10.244.1.19   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-bnwlj   1/1     Running   0          41s   10.244.1.21   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-gq29d   1/1     Running   0          45s   10.244.2.17   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-rp52v   1/1     Running   0          45s   10.244.1.20   k8s-node02   <none>           <none>
nginx-deployment-64ddb75745-sxch9   1/1     Running   0          42s   10.244.2.19   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-tt8tp   1/1     Running   0          37s   10.244.2.20   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-vtx8w   1/1     Running   0          45s   10.244.2.16   k8s-node01   <none>           <none>
nginx-deployment-64ddb75745-zr8c7   1/1     Running   0          39s   10.244.1.22   k8s-node02   <none>           <none>
[root@k8s-master mnt]# curl 10.244.2.19
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
[root@k8s-master mnt]# kubectl rollout status deployment/nginx-deployment
deployment "nginx-deployment" successfully rolled out
[root@k8s-master mnt]# kubectl rollout history deployment/nginx-deployment
deployment.apps/nginx-deployment
REVISION  CHANGE-CAUSE
2         kubectl apply --filename=deployment.yaml --record=true
3         kubectl apply --filename=deployment.yaml --record=true

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