k8s 的更新策略为滚动更新，通过新创建的RS（Replica Set）创建新的pod，等新的pod调度完成显示running，然后terminating掉老的RS下的pod，循环往复直至完成全部新pod的更新。
[root@master1 ~]# kubectl rollout history deployment myapp-v1
deployment.apps/myapp-v1
REVISION CHANGE-CAUSE
1
2
[root@master1 ~]#
[root@master1 ~]# kubectl rollout undo deployment myapp-v1 --to-revision=1
deployment.apps/myapp-v1 rolled back
[root@master1 ~]# kubectl rollout history deployment myapp-v1
deployment.apps/myapp-v1
REVISION CHANGE-CAUSE
2
3
[root@master1 ~]# kubectl describe deployment myapp-v1
Name: myapp-v1
Namespace: default
CreationTimestamp: Tue, 06 Sep 2022 11:00:16 +0800
Labels:
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=myapp,version=v1
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=myapp
version=v1
Containers:
myapp:
Image: janakiramm/myapp:v1
Port: 80/TCP
Host Port: 0/TCP
Environment:
Mounts:
Volumes:
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:
NewReplicaSet: myapp-v1-8448d48797 (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 22m deployment-controller Scaled up replica set myapp-v1-8448d48797 to 2
Normal ScalingReplicaSet 17m deployment-controller Scaled up replica set myapp-v1-8448d48797 to 4
Normal ScalingReplicaSet 15m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 3
Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 1
Normal ScalingReplicaSet 11m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 2
Normal ScalingReplicaSet 11m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 2
Normal ScalingReplicaSet 10m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 1
Normal ScalingReplicaSet 10m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 3
Normal ScalingReplicaSet 10m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 0
Normal ScalingReplicaSet 2m16s deployment-controller Scaled up replica set myapp-v1-8448d48797 to 1
Normal ScalingReplicaSet 95s (x4 over 2m2s) deployment-controller (combined from similar events): Scaled up replica set myapp-v1-8448d48797 to 3
Normal ScalingReplicaSet 9s deployment-controller Scaled down replica set myapp-v1-69d5787956 to 0
[root@master1 ~]# kubectl describe deployment myapp-v1
Name: myapp-v1
Namespace: default
CreationTimestamp: Tue, 06 Sep 2022 11:00:16 +0800
Labels:
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=myapp,version=v1
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=myapp
version=v1
Containers:
myapp:
Image: janakiramm/myapp:v1
Port: 80/TCP
Host Port: 0/TCP
Environment:
Mounts:
Volumes:
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:
NewReplicaSet: myapp-v1-8448d48797 (3/3 replicas created)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 35m deployment-controller Scaled up replica set myapp-v1-8448d48797 to 2
Normal ScalingReplicaSet 30m deployment-controller Scaled up replica set myapp-v1-8448d48797 to 4
Normal ScalingReplicaSet 28m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 3
Normal ScalingReplicaSet 24m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 1
Normal ScalingReplicaSet 24m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 2
Normal ScalingReplicaSet 24m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 2
Normal ScalingReplicaSet 23m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 1
Normal ScalingReplicaSet 23m deployment-controller Scaled up replica set myapp-v1-69d5787956 to 3
Normal ScalingReplicaSet 23m deployment-controller Scaled down replica set myapp-v1-8448d48797 to 0
Normal ScalingReplicaSet 15m deployment-controller Scaled up replica set myapp-v1-8448d48797 to 1
Normal ScalingReplicaSet 14m (x4 over 15m) deployment-controller (combined from similar events): Scaled up replica set m
Normal ScalingReplicaSet 13m deployment-controller Scaled down replica set myapp-v1-69d5787956 to 0
[root@master1 ~]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
myapp-v1-8448d48797-7cn4p 1/1 Running 0 15m app=myapp,pod-template-hash=8448d48797,version=v1
myapp-v1-8448d48797-7mhxk 1/1 Running 0 15m app=myapp,pod-template-hash=8448d48797,version=v1
myapp-v1-8448d48797-fkb46 1/1 Running 0 15m app=myapp,pod-template-hash=8448d48797,version=v1
滚动更新过程中新旧pod的创建过程如下：
[root@master1 ~]# kubectl get pods -l app=myapp -w
NAME READY STATUS RESTARTS AGE
myapp-v1-8448d48797-phjwf 1/1 Running 0 4m25s
myapp-v1-8448d48797-r5sn8 1/1 Running 0 9m40s
myapp-v1-8448d48797-vz4jj 1/1 Running 0 9m37s
# 更新了镜像，查看pod的创建过程
myapp-v1-69d5787956-x2vtr 0/1 Pending 0 0s
myapp-v1-69d5787956-x2vtr 0/1 Pending 0 0s
myapp-v1-69d5787956-x2vtr 0/1 ContainerCreating 0 4s
myapp-v1-69d5787956-x2vtr 0/1 ContainerCreating 0 13s
myapp-v1-69d5787956-x2vtr 1/1 Running 0 24s
myapp-v1-8448d48797-phjwf 1/1 Terminating 0 6m2s
myapp-v1-69d5787956-vcjsb 0/1 Pending 0 0s
myapp-v1-69d5787956-vcjsb 0/1 Pending 0 0s
myapp-v1-69d5787956-vcjsb 0/1 ContainerCreating 0 0s
myapp-v1-69d5787956-vcjsb 0/1 ContainerCreating 0 13s
myapp-v1-8448d48797-phjwf 0/1 Terminating 0 6m16s
myapp-v1-8448d48797-phjwf 0/1 Terminating 0 6m19s
myapp-v1-8448d48797-phjwf 0/1 Terminating 0 6m20s
myapp-v1-69d5787956-vcjsb 1/1 Running 0 24s
myapp-v1-8448d48797-vz4jj 1/1 Terminating 0 11m
myapp-v1-69d5787956-qq58n 0/1 Pending 0 5s
myapp-v1-69d5787956-qq58n 0/1 Pending 0 5s
myapp-v1-69d5787956-qq58n 0/1 ContainerCreating 0 11s
myapp-v1-69d5787956-qq58n 0/1 ContainerCreating 0 25s
myapp-v1-8448d48797-vz4jj 0/1 Terminating 0 12m
myapp-v1-8448d48797-vz4jj 0/1 Terminating 0 12m
myapp-v1-8448d48797-vz4jj 0/1 Terminating 0 12m
myapp-v1-69d5787956-qq58n 1/1 Running 0 31s
myapp-v1-8448d48797-r5sn8 1/1 Terminating 0 12m
myapp-v1-8448d48797-r5sn8 0/1 Terminating 0 12m
myapp-v1-8448d48797-r5sn8 0/1 Terminating 0 12m
myapp-v1-8448d48797-r5sn8 0/1 Terminating 0 12m
## 执行了回滚版本V1，查看新pod创建过程
myapp-v1-8448d48797-7cn4p 0/1 Pending 0 0s
myapp-v1-8448d48797-7cn4p 0/1 Pending 0 0s
myapp-v1-8448d48797-7cn4p 0/1 ContainerCreating 0 0s
myapp-v1-8448d48797-7cn4p 0/1 ContainerCreating 0 8s
myapp-v1-8448d48797-7cn4p 1/1 Running 0 12s
myapp-v1-69d5787956-qq58n 1/1 Terminating 0 8m53s
myapp-v1-8448d48797-7mhxk 0/1 Pending 0 0s
myapp-v1-8448d48797-7mhxk 0/1 Pending 0 2s
myapp-v1-8448d48797-7mhxk 0/1 ContainerCreating 0 3s
myapp-v1-8448d48797-7mhxk 0/1 ContainerCreating 0 15s
myapp-v1-69d5787956-qq58n 0/1 Terminating 0 9m9s
myapp-v1-69d5787956-qq58n 0/1 Terminating 0 9m10s
myapp-v1-69d5787956-qq58n 0/1 Terminating 0 9m10s
myapp-v1-8448d48797-7mhxk 1/1 Running 0 22s
myapp-v1-69d5787956-vcjsb 1/1 Terminating 0 9m43s
myapp-v1-8448d48797-fkb46 0/1 Pending 0 0s
myapp-v1-8448d48797-fkb46 0/1 Pending 0 1s
myapp-v1-8448d48797-fkb46 0/1 ContainerCreating 0 12s
myapp-v1-69d5787956-vcjsb 0/1 Terminating 0 10m
myapp-v1-69d5787956-vcjsb 0/1 Terminating 0 10m
myapp-v1-8448d48797-fkb46 0/1 ContainerCreating 0 45s
myapp-v1-69d5787956-vcjsb 0/1 Terminating 0 10m
myapp-v1-8448d48797-fkb46 1/1 Running 0 59s
myapp-v1-69d5787956-x2vtr 1/1 Terminating 0 11m
myapp-v1-69d5787956-x2vtr 0/1 Terminating 0 11m
myapp-v1-69d5787956-x2vtr 0/1 Terminating 0 11m
myapp-v1-69d5787956-x2vtr 0/1 Terminating 0 11m
更改滚动更新策略：
[root@master1 deployment]# kubectl describe deployment myapp-v1 -n default
Name: myapp-v1
Namespace: default
CreationTimestamp: Tue, 06 Sep 2022 11:00:16 +0800
Labels:
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=myapp,version=v1
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=myapp
version=v1
Containers:
myapp:
Image: janakiramm/myapp:v1
Port: 80/TCP
Host Port: 0/TCP
Environment:
Mounts:
Volumes:
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:
NewReplicaSet: myapp-v1-8448d48797 (3/3 replicas created)
Events:
[root@master1 deployment]# kubectl patch deployment myapp-v1 -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":1,"maxUnavailable":1}}}}' -n default
deployment.apps/myapp-v1 patched
[root@master1 deployment]# kubectl describe deployment myapp-v1 -n default
Name: myapp-v1
Namespace: default
CreationTimestamp: Tue, 06 Sep 2022 11:00:16 +0800
Labels:
Annotations: deployment.kubernetes.io/revision: 3
Selector: app=myapp,version=v1
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 1 max unavailable, 1 max surge
Pod Template:
Labels: app=myapp
version=v1
Containers:
myapp:
Image: janakiramm/myapp:v1
Port: 80/TCP
Host Port: 0/TCP
Environment:
Mounts:
Volumes:
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets:
NewReplicaSet: myapp-v1-8448d48797 (3/3 replicas created)
Events:
上面可以看到RollingUpdateStrategy: 1 max unavailable, 1 max surge
这个rollingUpdate更新策略变成了刚才设定的，因为我们设定的pod副本数是3，1和1表示最少不能少于2个pod，最多不能超过4个pod 。
这个就是通过控制RollingUpdateStrategy这个字段来设置滚动更新策略的
Deployment资源清单详解
apiVersion: apps/v1
kind: Deployment
metadata:
name: portal
namespace: ms
spec:
replicas: 1
selector:
matchLabels:
project: ms
app: portal
template:
metadata:
labels:
project: ms
app: portal
spec:
containers:
- name: portal
image: xianchao/portal:v1
imagePullPolicy: Always
ports:
- protocol: TCP
containerPort: 8080
resources: #资源配额
limits: #资源限制，最多可用的cpu和内存
cpu: 1
memory: 1Gi
requests： #最少需要多少资源才可以运行Pod
cpu: 0.5
memory: 1Gi
readinessProbe:
tcpSocket:
port: 8080
initialDelaySeconds: 60
periodSeconds: 10
livenessProbe:
tcpSocket:
port: 8080
initialDelaySeconds: 60
periodSeconds:
livenessProbe: 存活性探测
用于判断容器是否存活，即Pod是否为running状态，如果LivenessProbe探针探测到容器不健康，则kubelet将kill掉容器，并根据容器的重启策略是否重启。如果一个容器不包含LivenessProbe探针，则Kubelet认为容器的LivenessProbe探针的返回值永远成功。
tcpSocket:
port: 8080 #检测8080端口是否存在
initialDelaySeconds: 60 #Pod启动60s执行第一次检查
periodSeconds: 10 #第一次检查后每隔10s检查一次
readinessProbe: 就绪性探测
有时候应用程序可能暂时无法接受请求，比如Pod已经Running了，但是容器内应用程序尚未启动成功，在这种情况下，如果没有ReadinessProbe，则Kubernetes认为它可以处理请求了，然而此时，我们知道程序还没启动成功是不能接收用户请求的，所以不希望kubernetes把请求调度给它，则使用ReadinessProbe探针。
ReadinessProbe和livenessProbe可以使用相同探测方式，只是对Pod的处置方式不同，ReadinessProbe是将Pod IP:Port从对应的EndPoint列表中删除，而livenessProbe则Kill容器并根据Pod的重启策略来决定作出对应的措施。ReadinessProbe探针探测容器是否已准备就绪，如果未准备就绪则kubernetes不会将流量转发给此Pod。在Pod运行过程中，K8S仍然会每隔10s检测8080端口