环境
- kubernetes 1.20.4
- Spring Boot 2.5.0-M3
目标
在之前，提到过 deploy 相比较 rs，多了升级的一些功能。
下面演示 deploy 的滚动更新。
示例
Deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: busybox
spec:
selector:
matchLabels:
app: busybox
replicas: 8
template:
metadata:
labels:
app: busybox
spec:
terminationGracePeriodSeconds: 5
containers:
- name: busybox
image: busybox:1.30.0
command: ["/bin/sh", "-c", "sleep 3600"]
修改镜像版本
kubectl set image deployment/busybox busybox=busybox:1.31.0 --record
查看滚动操作
[root@master ~]# kubectl rollout status deployment busybox
Waiting for deployment "busybox" rollout to finish: 4 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 4 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 4 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 4 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 5 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 5 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 6 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 6 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 6 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 6 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 6 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 7 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 7 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 7 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 7 out of 8 new replicas have been updated...
Waiting for deployment "busybox" rollout to finish: 2 old replicas are pending termination...
Waiting for deployment "busybox" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "busybox" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "busybox" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "busybox" rollout to finish: 6 of 8 updated replicas are available...
Waiting for deployment "busybox" rollout to finish: 7 of 8 updated replicas are available...
deployment "busybox" successfully rolled out
可以看到旧的 Pod 慢慢被新的替换，直接全部变成新的版本。
总结
执行了 deploy 默认的滚动更新操作。在更新的过程中，并不是先把旧的完全结束，再创建新的。
而是先停一部分，启动一部分这样循环，直接完全替换，这就是所说的滚动更新。