[K8S]Deployment滚动更新和回滚、水平伸缩

- 创建Deployment
- 滚动更新
- ReplicaSet
- 回滚
- 水平伸缩

@创建Deployment

首先创建一个deployment，pod副本数为3，使用镜像nginx:1.19，并创建服务

test-deploy-svc.yaml 的内容如下

apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: web
name: web
namespace: default
spec:
replicas: 3
selector:
matchLabels:
app: web
strategy: {}
template:
metadata:
labels:
app: web
spec:
containers:
- image: nginx:1.19
name: nginx
---
apiVersion: v1
kind: Service
metadata:
labels:
app: web
name: web
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
app: web
type: NodePort


创建deployment

[[email&＃160;protected] ~]# kubectl apply -f test-deploy-svc.yaml
deployment.apps/web created
service/web created
[[email&＃160;protected] ~]#

查看svc的NodePort，为31147

[[email&＃160;protected] ~]# kubectl get svc -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
kubernetes ClusterIP 10.96.0.1 443/TCP 19d
web NodePort 10.99.203.162 80:31147/TCP 49s app=web
[[email&＃160;protected] ~]#


查询svc关联的pod

[[email&＃160;protected] ~]# kubectl get endpoints
NAME ENDPOINTS AGE
kubernetes 192.168.231.121:6443 19d
web 10.244.169.161:80,10.244.36.84:80,10.244.36.88:80 2m28s
[[email&＃160;protected] ~]#


浏览器打开主页，http://:31147

同时打开控制台，查看nginx版本，这里是1.19.10

@滚动更新

方法1： kubectl set image deployment web nginx=nginx:1.20 

[[email&＃160;protected] ~]# kubectl set image deployment web nginx=nginx:1.20
deployment.apps/web image updated
[[email&＃160;protected] ~]#

刷新浏览器页面浏览器 版本更新为nginx/1.20.1

pod在这个过程会滚动更新（下一个方法中详述）；查看endpoints，svc关联的pod地址变了

[[email&＃160;protected] ~]# kubectl get endpoints
NAME ENDPOINTS AGE
kubernetes 192.168.231.121:6443 19d
web 10.244.169.160:80,10.244.36.81:80,10.244.36.82:80 13m
[[email&＃160;protected] ~]#

方法2：修改yaml文件，再次apply，将版本改为1.21

[[email&＃160;protected] ~]# grep image test-deploy-svc.yaml
- image: nginx:1.19
[[email&＃160;protected] ~]# vim test-deploy-svc.yaml
[[email&＃160;protected] ~]# grep image test-deploy-svc.yaml
- image: nginx:1.21
[[email&＃160;protected] ~]#

先记录此刻1.20版本pod的NAME和IP

[[email&＃160;protected] ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-7f5844f89c-6sdxt 1/1 Running 0 5m28s 10.244.169.160 k8s-node2
web-7f5844f89c-cxqjf 1/1 Running 0 5m29s 10.244.36.82 k8s-node1
web-7f5844f89c-m6655 1/1 Running 0 5m26s 10.244.36.81 k8s-node1
[[email&＃160;protected] ~]#


执行kubectl apply -f test-deploy-svc.yaml更新

[[email&＃160;protected] ~]# kubectl apply -f test-deploy-svc.yaml
deployment.apps/web configured
service/web unchanged
[[email&＃160;protected] ~]#

不断使用命令kubectl get pod -o wide查看pod创建情况

--> 正在创建一个新pod，其状态为ContainerCreating

[[email&＃160;protected] ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-7f5844f89c-6sdxt 1/1 Running 0 6m7s 10.244.169.160 k8s-node2
web-7f5844f89c-cxqjf 1/1 Running 0 6m8s 10.244.36.82 k8s-node1
web-7f5844f89c-m6655 1/1 Running 0 6m5s 10.244.36.81 k8s-node1
web-d779974b6-j72dv 0/1 ContainerCreating 0 4s k8s-node1
[[email&＃160;protected] ~]#

--> 第一个新pod状态变为Running，一个旧pod进入Terminating，同时创建第二个新pod

[[email&＃160;protected] ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-7f5844f89c-6sdxt 1/1 Running 0 6m22s 10.244.169.160 k8s-node2
web-7f5844f89c-cxqjf 1/1 Running 0 6m23s 10.244.36.82 k8s-node1
web-7f5844f89c-m6655 1/1 Terminating 0 6m20s 10.244.36.81 k8s-node1
web-d779974b6-j72dv 1/1 Running 0 19s 10.244.36.90 k8s-node1
web-d779974b6-j9fkf 0/1 ContainerCreating 0 0s k8s-node2
[[email&＃160;protected] ~]#

……

--> 创建了三个新pod，旧的三个pod处于Terminating状态

[[email&＃160;protected] ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-7f5844f89c-6sdxt 0/1 Terminating 0 6m25s 10.244.169.160 k8s-node2
web-7f5844f89c-cxqjf 1/1 Terminating 0 6m26s 10.244.36.82 k8s-node1
web-7f5844f89c-m6655 0/1 Terminating 0 6m23s 10.244.36.81 k8s-node1
web-d779974b6-9nmb6 1/1 Running 0 2s 10.244.36.91 k8s-node1
web-d779974b6-j72dv 1/1 Running 0 22s 10.244.36.90 k8s-node1
web-d779974b6-j9fkf 1/1 Running 0 3s 10.244.169.164 k8s-node2
[[email&＃160;protected] ~]#

……

--> 三个pod全部"更新"为新版本

[[email&＃160;protected] ~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
web-d779974b6-9nmb6 1/1 Running 0 11s 10.244.36.91 k8s-node1
web-d779974b6-j72dv 1/1 Running 0 31s 10.244.36.90 k8s-node1
web-d779974b6-j9fkf 1/1 Running 0 12s 10.244.169.164 k8s-node2
[[email&＃160;protected] ~]#

以上步骤可以看到pod分配了新的IP，查看endpoints也可以观察到service绑定的pod地址更新了

[[email&＃160;protected] ~]# kubectl get ep
NAME         ENDPOINTS                                           AGE
kubernetes   192.168.231.121:6443                                19d
web          10.244.169.164:80,10.244.36.90:80,10.244.36.91:80   30m
[[email&＃160;protected] ~]#

刷新浏览器页面，查看nginx版本更新为 nginx/1.21.1

@ReplicaSet

常用命令：

kubectl get replicaset
kubectl describe deployment
kubectl describe

滚动升级的执行者是 控制器 replicaset(rs) ，管理pod的副本数量，也会记录发布的版本

用命令kubectl get replicaset查看rs，最后一行期望副本数为3的web-d779974b6是最近一次的部署，对应上述最新的pod，可以发现 pod NAME = deployment NAME + rs NAME + 随机字符串

[[email&＃160;protected] ~]# kubectl get replicaset
NAME DESIRED CURRENT READY AGE
web-7f5844f89c 0 0 0 30m
web-bc7cc9f65 0 0 0 40m
web-d779974b6 3 3 3 24m
[[email&＃160;protected] ~]#


查看deployment详细信息可以看到滚动升级的过程，关注下述最后的Events部分

(但是过一段时间再执行就会变成 Events:  )

[[email&＃160;protected] ~]# kubectl describe deployment web
Name: web
Namespace: default
CreationTimestamp: Sat, 14 Aug 2021 14:32:35 +0800
Labels: app=web
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=web
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=web
Containers:
nginx:
Image: nginx:1.21
Port:
Host Port:
Environment:
Mounts:
Volumes:
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:
NewReplicaSet: web-d779974b6 (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 59m deployment-controller Scaled up replica set web-d779974b6 to 1
Normal ScalingReplicaSet 58m deployment-controller Scaled down replica set web-7f5844f89c to 2
Normal ScalingReplicaSet 58m deployment-controller Scaled up replica set web-d779974b6 to 2
Normal ScalingReplicaSet 58m (x3 over 58m) deployment-controller (combined from similar events): Scaled down replica set web-7f5844f89c to 0
[[email&＃160;protected] ~]#


查看rs信息也可以看到标记的版本

[[email&＃160;protected] ~]# kubectl describe rs web-d779974b6
Name: web-d779974b6
Namespace: default
Selector: app=web,pod-template-hash=d779974b6
Labels: app=web
pod-template-hash=d779974b6
Annotations: deployment.kubernetes.io/desired-replicas: 3
deployment.kubernetes.io/max-replicas: 4
deployment.kubernetes.io/revision: 3
Controlled By: Deployment/web
Replicas: 3 current / 3 desired
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
Labels: app=web
pod-template-hash=d779974b6
Containers:
nginx:
Image: nginx:1.21
Port:
Host Port:
Environment:
Mounts:
Volumes:
Events:
[[email&＃160;protected] ~]#


@回滚

常用命令：
kubectl rollout history deployment web
kubectl rollout undo deployment web
kubectl rollout undo deployment web --to-revision=

查看历史发布版本

[[email&＃160;protected] ~]# kubectl rollout history deployment web
deployment.apps/web
REVISION CHANGE-CAUSE
1
2
3
[[email&＃160;protected] ~]#

说明：部署的时候加上--record CHANGE-CAUSE会有记录

[[email&＃160;protected] ~]# kubectl set image deployment web nginx=nginx:1.21 --record
deployment.apps/web image updated
[[email&＃160;protected] ~]# kubectl rollout history deployment web
deployment.apps/web
REVISION CHANGE-CAUSE
1
4
5 kubectl set image deployment web nginx=nginx:1.21 --record=true
[[email&＃160;protected] ~]#


回滚到上一个版本（常用）

[[email&＃160;protected] ~]# kubectl rollout undo deployment web
deployment.apps/web rolled back
[[email&＃160;protected] ~]#

可以查看到rs的变化

[[email&＃160;protected] ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
web-7f5844f89c 3 3 3 88m
web-bc7cc9f65 0 0 0 98m
web-d779974b6 0 0 0 82m
[[email&＃160;protected] ~]#

@水平伸缩

方法1：修改yaml文件中replicas的值

方法2：使用命令 kubectl scale deployment web --replicas=

例如，使用方法2缩容到2个pod

[[email&＃160;protected] ~]# kubectl scale deployment web --replicas=2
deployment.apps/web scaled
[[email&＃160;protected] ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
web-d779974b6-6rctw 1/1 Running 0 5m41s
web-d779974b6-dv7fh 1/1 Running 0 5m40s
web-d779974b6-j6n9r 0/1 Terminating 0 5m38s
[[email&＃160;protected] ~]#
[[email&＃160;protected] ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
web-d779974b6-6rctw 1/1 Running 0 5m50s
web-d779974b6-dv7fh 1/1 Running 0 5m49s
[[email&＃160;protected] ~]#
[[email&＃160;protected] ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
web-7f5844f89c 0 0 0 128m
web-bc7cc9f65 0 0 0 138m
web-d779974b6 2 2 2 122m
[[email&＃160;protected] ~]#

再使用方法1扩容到3个pod

[[email&＃160;protected] ~]# kubectl apply -f test-deploy-svc.yaml
deployment.apps/web configured
service/web unchanged
[[email&＃160;protected] ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
web-d779974b6-6rctw 1/1 Running 0 7m34s
web-d779974b6-dv7fh 1/1 Running 0 7m33s
web-d779974b6-n8p6d 1/1 Running 0 5s
[[email&＃160;protected] ~]#
[[email&＃160;protected] ~]# kubectl get rs
NAME DESIRED CURRENT READY AGE
web-7f5844f89c 0 0 0 131m
web-bc7cc9f65 0 0 0 141m
web-d779974b6 3 3 3 125m
[[email&＃160;protected] ~]#