一、重启策略
pod的重启策略有3种，如下：
- Always：容器失效时，自动重启该容器，这是默认值
- OnFailure：容器停止运行且退出码不为0时重启
- Never：不论状态为何，都不重启该容器
重启策略适用于pod对象中的所有容器，首次需要重启的容器，将在其需要时立即进行重启，随后再次需要重启的操作将由kubelet延迟一段时间后进行，且反复的重启操作的延迟时长为10s，20s，40s，80s，160s，300s，300s是最大延迟时长
如下，修改pod_restartPolicy.yaml文件，其中restartPolicy字段即设置重启策略，这里需要注意的是，restartPolicy字段跟containers字段是平行的，是对所有容器生效的
apiVersion: v1
kind: Namespace
metadata:
name: dev
---
apiVersion: v1
kind: Pod
metadata:
name: pod-nginx
namespace: dev
labels:
user: redrose2100
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
httpGet:
scheme: HTTP
port: 80
path: /hello
restartPolicy: Never使用如下命令创建pod
[root@master resource_manage]# kubectl apply -f pod_restartPolicy.yaml
namespace/dev created
pod/pod-nginx created
[root@master resource_manage]#通过如下命令查询，可以发现这里因为设置Never重启策略，所以这里没有重启痕迹
[root@master resource_manage]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
pod-nginx 0/1 Completed 0 25m
[root@master resource_manage]# kubectl describe pod pod-nginx -n dev
Name: pod-nginx
Namespace: dev
Priority: 0
Node: node2/192.168.16.42
Start Time: Thu, 24 Mar 2022 15:35:21 +0800
Labels: user=redrose2100
Annotations: <none>
Status: Succeeded
IP: 10.244.2.42
IPs:
IP: 10.244.2.42
Containers:
nginx:
Container ID: docker://4203b0f3ccd87a1df0012c08ada6fb6d1cbac583da1b63dffc5d2ceb194c0255
Image: nginx:1.17.1
Image ID: docker-pullable://nginx@sha256:b4b9b3eee194703fc2fa8afa5b7510c77ae70cfba567af1376a573a967c03dbb
Port: 80/TCP
Host Port: 0/TCP
State: Terminated
Reason: Completed
Exit Code: 0
Started: Thu, 24 Mar 2022 15:35:21 +0800
Finished: Thu, 24 Mar 2022 15:35:51 +0800
Ready: False
Restart Count: 0
Liveness: http-get http://:80/hello delay=0s timeout=1s period=10s #success=1 #failure=3
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-7sn8d (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
kube-api-access-7sn8d:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 25m default-scheduler Successfully assigned dev/pod-nginx to node2
Normal Pulled 25m kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 25m kubelet Created container nginx
Normal Started 25m kubelet Started container nginx
Warning Unhealthy 24m (x3 over 25m) kubelet Liveness probe failed: HTTP probe failed with statuscode: 404
Normal Killing 24m kubelet Stopping container nginx
[root@master resource_manage]#使用如下命令可以删除资源
[root@master resource_manage]# kubectl delete -f pod_restartPolicy.yaml
namespace "dev" deleted
pod "pod-nginx" deleted
[root@master resource_manage]#
二、重启策略设置建议
因为重启策略默认的就是Always，这也是合理的，因此在一般情况下，重启策略不需要设置，这里仅仅是作为知识点拿出来展示一下，在实际使用中，在大多数情况下都不需要进行重启策略配置
