Kubernetes之四 Deployment控制器更新

Deployment(简写为deploy)是kubernetes控制器的又一种实现.只需要在 Deployment 中描述您想要的目标状态是什么，Deployment controller 就会帮您将 Pod 和ReplicaSet 的实际状态改变到您的目标状态.

比如期望运行二个nginx pod,当一个pod因为意外下线时， Deployment 会根据你描述的状态再起一个pod,这就是所谓的控制循环。Deployment会根据申明的RS控制器配置，控制对应的pod的数量和状态。

下面是Deploymen的更新机制

1.首先，创建-一个新的RS控制器，版本为v2 ;

2接着将旧控制器的pod陆续下线，同时新的RS控制器同步上线对应Pod;

3. Pod更新完成后，弃用旧的RS控制器，滚动发布就此完成。

部署nginx应用，以下面模板进行部署，滚动策略，最多新增一个（maxSurge），最少下线一个（maxUnavailable）

apiVersion: apps/v1

kind: Deployment

metadata:

name: nginx

spec:

replicas: 3

minReadySeconds: 10

strategy:

rollingUpdate:

maxSurge: 1

maxUnavailable: 1

type: RollingUpdate

selector:

matchLabels:

app: nginx

template:

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx:1.10-alpine

ports:

- containerPort: 80

name: http

readinessProbe:

periodSeconds: 1

httpGet:

path: /

port: http

kubectl apply -f 进行部署，kubectl get rs -o wide进行查看

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-5745bb45d7 3 3 3 30s nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

升级到nginx1.13,再进行查看

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-567c45c748 2 2 0 3s nginx nginx:1.13-alpine app=nginx,pod-template-hash=567c45c748

deploy-nginx-5745bb45d7 2 2 2 3m5s nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-567c45c748 3 3 2 30s nginx nginx:1.13-alpine app=nginx,pod-template-hash=567c45c748

deploy-nginx-5745bb45d7 0 0 0 3m32s nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

用下面命令查看历史版本

[root@master ~]# kubectl rollout history deployment/deploy-nginx

deployment.apps/deploy-nginx

REVISION CHANGE-CAUSE

1 <none>

2 <none>

版本回滚 kubectl rollout undo deployment/deploy-nginx --to-revision=0

回滚结果

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-567c45c748 0 0 0 15m nginx nginx:1.13-alpine app=nginx,pod-template-hash=567c45c748

deploy-nginx-5745bb45d7 3 3 3 18m nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

金丝雀发布

金丝雀发布一般先发 1 台，或者一个小比例，例如 2% 的服务器，主要做流量验证用，也称为金丝雀 (Canary) 测试（国内常称灰度测试）如果金丝测试通过，则把剩余的 V1 版本全部升级为 V2 版本。如果金丝雀测试失败，则直接回退金丝雀，发布失败

kubectl set image deployment deploy-nginx nginx=nginx:1.14-alpine && kubectl rollout pause deployment deploy-nginx

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-567c45c748 0 0 0 34m nginx nginx:1.13-alpine app=nginx,pod-template-hash=567c45c748

deploy-nginx-5745bb45d7 2 2 2 37m nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

deploy-nginx-754874567 2 2 2 94s nginx nginx:1.14-alpine app=nginx,pod-template-hash=754874567

如果有问题，可以通过版本回滚 kubectl rollout undo deployment/deploy-nginx --to-revision=0进行回滚

或者测试几天正常，可以继续更新

[root@master ~]# kubectl get rs -o wide

NAME DESIRED CURRENT READY AGE CONTAINERS IMAGES SELECTOR

deploy-nginx-567c45c748 0 0 0 37m nginx nginx:1.13-alpine app=nginx,pod-template-hash=567c45c748

deploy-nginx-5745bb45d7 0 0 0 40m nginx nginx:1.10-alpine app=nginx,pod-template-hash=5745bb45d7

deploy-nginx-754874567 3 3 3 5m23s nginx nginx:1.14-alpine app=nginx,pod-template-hash=754874567