Kubernetes Deployment 之扩缩容与滚动更新
Deployment 扩缩容
扩缩容非常简单，我们可以直接调整 replica 副本数目，然后 kubectl apply指定进行动态更新。下面将nginx-deployment动态改为 1 个 Pod 和 3 个 Pod 的操作
yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment-nginx
namespace: default
labels:
app: deployment-nginx
spec:
replicas: 2 # 将此处动态改为 1 或者 3
selector:
matchLabels:
app: pod-nginx
template:
metadata:
labels:
app: pod-nginx
spec:
containers:
- name: nginx
image: docker.io/k8s-test:v1.0
imagePullPolicy: IfNotPresent
ports:
- containerPort: 80root@k8s-master1:~# kubectl apply -f deploy-nginx.yaml
deployment.apps/deployment-nginx configured
root@k8s-master1:~# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
deployment-nginx 1/1 1 1 17h
root@k8s-master1:~# kubectl apply -f deploy-nginx.yaml
deployment.apps/deployment-nginx configured
root@k8s-master1:~# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
deployment-nginx 3/3 3 3 17h
# 它也会识别原来的 Pod 有没有被更新，如果没有被更新，它仍然会继续被保留运行
root@k8s-master1:~# kubectl get pods -owide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
deployment-nginx-6977747dd9-knx9r 1/1 Running 0 31s 10.244.194.126 k8s-worker1 <none> <none>
deployment-nginx-6977747dd9-nqxgd 1/1 Running 0 31s 10.244.194.125 k8s-worker1 <none> <none>
deployment-nginx-6977747dd9-sz42q 1/1 Running 1 (34m ago) 17h 10.244.126.24 k8s-worker2 <none> <none>Deployment 滚动更新策略
Deployment 更新策略分为两种，分别为Recreate和RollingUpdate。Recreate是将所有 Pod 全部杀死，然后启动新版本，这是一个极其危险的行为，几乎不被使用。滚动更新是指，新增一定数量的 Pod 后，再杀死一定的数量的 Pod。Deployment 默认使用滚动更新策略。
实现滚动更新需要设置MaxSurge最大 Pod 新增数量和MaxUnavailable最大 Pod 不可用数据数目。它们可以设置成整数或者百分比，且两者不能同时为0，不然无法根本更新。以副本数 3 为例，如果我们 MaxSurge设置为 10%，那么我们新增个数为 0.3，这里需要向上取整 ，即个数为1；同理我们 MaxUnavailable设置为 10%，这里我们允许不可用的个数也为 0.3，这里要向下取整为 0；最终我们的更新策略是要等到 4 个 Pod 完全在运行状态，滚动更新才回去杀死 1 个老 Pod。
Deployment 滚动更新使用
-
我们先将
k8s-test:v1.0镜像标记为k8s-test:v1.1root@k8s-worker1:~# ctr -n k8s.io image tag docker.io/library/k8s-test:v1.0 docker.io/library/k8s-test:v1.1 docker.io/library/k8s-test:v1.1 root@k8s-worker2:~# ctr -n k8s.io image tag docker.io/library/k8s-test:v1.0 docker.io/library/k8s-test:v1.1 docker.io/library/k8s-test:v1.1 -
修改
yaml镜像版本号和更新策略yamlapiVersion: apps/v1 kind: Deployment metadata: name: deployment-nginx namespace: default labels: app: deployment-nginx spec: strategy: rollingUpdate: maxSurge: 10% maxUnavailable: 10% replicas: 2 selector: matchLabels: app: pod-nginx template: metadata: labels: app: pod-nginx spec: containers: - name: nginx image: docker.io/k8s-test:v1.1 imagePullPolicy: IfNotPresent ports: - containerPort: 80 -
执行如下指令开启 Pods 监听
kubectl get pods -owide -w -
更新过程如下，旧的 Pod 会先被标记，但不是真的被终止
root@k8s-master1:~# kubectl get pods -owide -w NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES deployment-nginx-6977747dd9-knx9r 1/1 Running 0 30m 10.244.194.126 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-nqxgd 1/1 Running 0 30m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-sz42q 1/1 Running 1 (63m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-nqxgd 1/1 Terminating 0 35m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6c94d644bd-ft9s6 0/1 Pending 0 0s <none> <none> <none> <none> deployment-nginx-6c94d644bd-ft9s6 0/1 Pending 0 0s <none> k8s-worker2 <none> <none> deployment-nginx-6c94d644bd-ft9s6 0/1 ContainerCreating 0 0s <none> k8s-worker2 <none> <none> deployment-nginx-6977747dd9-nqxgd 1/1 Terminating 0 35m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-nqxgd 0/1 Terminating 0 35m <none> k8s-worker1 <none> <none> deployment-nginx-6c94d644bd-ft9s6 0/1 ContainerCreating 0 0s <none> k8s-worker2 <none> <none> deployment-nginx-6977747dd9-nqxgd 0/1 Terminating 0 35m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6c94d644bd-ft9s6 1/1 Running 0 1s 10.244.126.26 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-nqxgd 0/1 Terminating 0 35m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-nqxgd 0/1 Terminating 0 35m 10.244.194.125 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-sz42q 1/1 Terminating 1 (69m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6c94d644bd-sj4hv 0/1 Pending 0 0s <none> <none> <none> <none> deployment-nginx-6c94d644bd-sj4hv 0/1 Pending 0 0s <none> k8s-worker1 <none> <none> deployment-nginx-6c94d644bd-sj4hv 0/1 ContainerCreating 0 0s <none> k8s-worker1 <none> <none> deployment-nginx-6977747dd9-sz42q 1/1 Terminating 1 (69m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-sz42q 0/1 Terminating 1 (69m ago) 17h <none> k8s-worker2 <none> <none> deployment-nginx-6c94d644bd-sj4hv 0/1 ContainerCreating 0 0s <none> k8s-worker1 <none> <none> deployment-nginx-6c94d644bd-sj4hv 1/1 Running 0 1s 10.244.194.127 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-sz42q 0/1 Terminating 1 (69m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-knx9r 1/1 Terminating 0 35m 10.244.194.126 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-sz42q 0/1 Terminating 1 (69m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-sz42q 0/1 Terminating 1 (69m ago) 17h 10.244.126.24 k8s-worker2 <none> <none> deployment-nginx-6977747dd9-knx9r 1/1 Terminating 0 35m 10.244.194.126 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-knx9r 0/1 Terminating 0 35m <none> k8s-worker1 <none> <none> deployment-nginx-6977747dd9-knx9r 0/1 Terminating 0 35m 10.244.194.126 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-knx9r 0/1 Terminating 0 35m 10.244.194.126 k8s-worker1 <none> <none> deployment-nginx-6977747dd9-knx9r 0/1 Terminating 0 35m 10.244.194.126 k8s-worker1 <none> <none> -
查看更新后的结果
root@k8s-master1:~# kubectl get pods -owide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES deployment-nginx-6c94d644bd-ft9s6 1/1 Running 0 4m55s 10.244.126.26 k8s-worker2 <none> <none> deployment-nginx-6c94d644bd-sj4hv 1/1 Running 0 4m54s 10.244.194.127 k8s-worker1 <none> <none> root@k8s-master1:~# kubectl get deploy NAME READY UP-TO-DATE AVAILABLE AGE deployment-nginx 2/2 2 2 17h root@k8s-master1:~# kubectl get rs NAME DESIRED CURRENT READY AGE deployment-nginx-6977747dd9 0 0 0 17h deployment-nginx-6c94d644bd 2 2 2 6m1s