三种策略
Kubernetes 中的 Pod 支持以下三种重启策略：
-
Always：
-
描述：无论容器退出的原因是什么，都会自动重启容器。
-
默认值：如果未指定重启策略，Kubernetes 默认使用 Always。
-
-
OnFailure：
-
描述：仅当容器以非零退出码终止时，才会重启容器。
-
条件：需要指定退出码来触发重启。
-
-
Never：
- 描述：不论容器退出的原因是什么，都不会重启容器。
重启延迟
-
首次重启：首次需要重启的容器将立即进行重启。
-
后续重启：随后如果再次需要重启，kubelet 将会引入延迟，延迟时长从 10 秒开始，并呈指数增长。
-
延迟时长序列：10s、20s、40s、80s、160s，之后达到最大延迟时长。
-
最大延迟时长：300s，这是后续重启操作的最大延迟时长。
Never
可以发现pod不会重启
bash
[root@k8s-master ~]# vim pod-restartpolicy.yaml
---
apiVersion: v1
kind: Pod
metadata:
name: pod-restartpolicy
namespace: test
spec:
restartPolicy: Never #论容器退出的原因是什么，都不会重启容器
containers:
- name: nginx
image: nginx:1.17.1
ports:
- containerPort: 80
name: nginx-port
livenessProbe:
httpGet:
scheme: HTTP
port: 80
path: /hello
[root@k8s-master ~]# kubectl apply -f pod-restartpolicy.yaml
Error from server (NotFound): error when creating "pod-restartpolicy.yaml": namespaces "test" not found
[root@k8s-master ~]# kubectl create ns test
namespace/test created
[root@k8s-master ~]# kubectl apply -f pod-restartpolicy.yaml
pod/pod-restartpolicy created
[root@k8s-master ~]# kubectl describe pod pod-restartpolicy -n test
Name: pod-restartpolicy
Namespace: test
Priority: 0
Node: k8s-node2/192.168.58.233
Start Time: Tue, 14 Jan 2025 20:45:51 -0500
Labels: <none>
Annotations: cni.projectcalico.org/containerID: 77f405fd3543f24391d29b1f878fff24dda621f6583dd7df8e7020da258b9f4d
cni.projectcalico.org/podIP: 10.244.169.129/32
cni.projectcalico.org/podIPs: 10.244.169.129/32
Status: Pending
IP:
IPs: <none>
Containers:
nginx:
Container ID:
Image: nginx:1.17.1
Image ID:
Port: 80/TCP
Host Port: 0/TCP
State: Waiting
Reason: ContainerCreating
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-sf6xn (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
kube-api-access-sf6xn:
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 22s default-scheduler Successfully assigned test/pod-restartpolicy to k8s-node2
Normal Pulling 20s kubelet Pulling image "nginx:1.17.1"
[root@k8s-master ~]# kubectl describe pod pod-restartpolicy -n test
Name: pod-restartpolicy
Namespace: test
Priority: 0
Node: k8s-node2/192.168.58.233
Start Time: Tue, 14 Jan 2025 20:45:51 -0500
Labels: <none>
Annotations: cni.projectcalico.org/containerID: 77f405fd3543f24391d29b1f878fff24dda621f6583dd7df8e7020da258b9f4d
cni.projectcalico.org/podIP:
cni.projectcalico.org/podIPs:
Status: Running
IP: 10.244.169.129
IPs:
IP: 10.244.169.129
Containers:
nginx:
Container ID: docker://19f7e2ca6a7f4a9487b75fc5dee7d85cf2baef4547ae8b6f1d68f8dfd5d7bb1a
Image: nginx:1.17.1
Image ID: docker-pullable://nginx@sha256:b4b9b3eee194703fc2fa8afa5b7510c77ae70cfba567af1376a573a967c03dbb
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Tue, 14 Jan 2025 20:46:18 -0500
Ready: True
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-sf6xn (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-sf6xn:
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 50s default-scheduler Successfully assigned test/pod-restartpolicy to k8s-node2
Normal Pulling 48s kubelet Pulling image "nginx:1.17.1"
Normal Pulled 24s kubelet Successfully pulled image "nginx:1.17.1" in 24.531177953s
Normal Created 23s kubelet Created container nginx
Normal Started 23s kubelet Started container nginx
Warning Unhealthy 0s (x3 over 20s) kubelet Liveness probe failed: HTTP probe failed with statuscode: 404
Normal Killing 0s kubelet Stopping container nginx
[root@k8s-master ~]# kubectl get pod pod-restartpolicy -n test
NAME READY STATUS RESTARTS AGE
pod-restartpolicy 0/1 Completed 0 53sAlways
可以发现pod会一直重启
bash
[root@k8s-master ~]# vim pod-restartpolicy.yaml
^C[root@k8s-master ~]# cat pod-restartpolicy.yaml
---
apiVersion: v1
kind: Pod
metadata:
name: pod-restartpolicy
namespace: test
spec:
restartPolicy: Always #论容器退出的原因是什么，都不会重启容器
containers:
- name: nginx
image: nginx:1.17.1
ports:
- containerPort: 80
name: nginx-port
livenessProbe:
httpGet:
scheme: HTTP
port: 80
path: /hello
[root@k8s-master ~]# kubectl delete pod-restartpolicy.yaml
error: the server doesn't have a resource type "pod-restartpolicy"
[root@k8s-master ~]# kubectl delete -f pod-restartpolicy.yaml
pod "pod-restartpolicy" deleted
[root@k8s-master ~]# kubectl apply -f pod-restartpolicy.yaml
pod/pod-restartpolicy created
[root@k8s-master ~]# kubectl get pod pod-restartpolicy -n test -w
NAME READY STATUS RESTARTS AGE
pod-restartpolicy 1/1 Running 0 5s
pod-restartpolicy 1/1 Running 1 31sPod常见状态转换场景
| Pod中的容器数 | Pod状态 | 发生事件 | Always | OnFailure | Never |
|---|---|---|---|---|---|
| 包含一个容器 | Running | 容器成功退出 | Running | Succeeded | Succeeded |
| 包含一个容器 | Running | 容器失败退出 | Running | Running | Failed |
| 包含两个容器 | Running | 1个容器失败退出 | Running | Running | Running |
| 包含两个容器 | Running | 容器内存溢出挂掉 | Running | Running | Failed |
注释：
-
对于
Always重启策略，容器将立即重启。 -
对于
OnFailure和Never重启策略，如果容器成功退出且退出码为0，Pod状态将变为Succeeded。 -
对于
Always重启策略，容器将立即重启。 -
对于
OnFailure重启策略，容器将以非零退出码退出，因此会重启。 -
对于
Never重启策略，容器将不会重启，Pod状态将变为Failed。 -
对于
Always重启策略，由于内存溢出导致的容器终止将重启容器。 -
对于
OnFailure重启策略，内存溢出导致的容器终止会触发重启，因为退出码是非零的。 -
对于
Never重启策略，容器将不会重启，Pod中其他容器继续运行，但失败的容器状态将为Terminated。