preStop和postStart
与探针类似其实叫webhook钩子
我们对我们的pod加一个钩子,两个钩子分别是:preStop和postStart
postStart:在容器创建完成后立即运行的钩子语句,类似操作系统上的rc.local这个文件里面内容
preStop:在容器中止之前立即运行的一个钩子语句,类似于关机之前执行的一个操作
这两个和我们的操作系统很相似,一个preStop和postStart
webhook理解成触发器
查看一下
kubectl explain pod.spec.containers
lifecycle <Object>
Actions that the management system should take in response to container
lifecycle events. Cannot be updated.[root@k8s-master1 ~]# kubectl explain pod.spec.containers.lifecycle
KIND: Pod
VERSION: v1
RESOURCE: lifecycle <Object>
DESCRIPTION:
Actions that the management system should take in response to container
lifecycle events. Cannot be updated.
Lifecycle describes actions that the management system should take in
response to container lifecycle events. For the PostStart and PreStop
lifecycle handlers, management of the container blocks until the action is
complete, unless the container process fails, in which case the handler is
aborted.
FIELDS:
postStart <Object>
#容器创造后立即运行
PostStart is called immediately after a container is created. If the
handler fails, the container is terminated and restarted according to its
restart policy. Other management of the container blocks until the hook
completes. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
preStop <Object>
#容器结束前运行的
PreStop is called immediately before a container is terminated due to an
API request or management event such as liveness/startup probe failure,
preemption, resource contention, etc. The handler is not called if the
container crashes or exits. The Pod's termination grace period countdown
begins before the PreStop hook is executed. Regardless of the outcome of
the handler, the container will eventually terminate within the Pod's
termination grace period (unless delayed by finalizers). Other management
of the container blocks until the hook completes or until the termination
grace period is reached. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks一般来说是个命令行
kubectl explain pod.spec.containers.lifecycle.postStart
KIND: Pod
VERSION: v1
RESOURCE: postStart <Object>
DESCRIPTION:
PostStart is called immediately after a container is created. If the
handler fails, the container is terminated and restarted according to its
restart policy. Other management of the container blocks until the hook
completes. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
LifecycleHandler defines a specific action that should be taken in a
lifecycle hook. One and only one of the fields, except TCPSocket must be
specified.
FIELDS:
exec <Object>
#命令行
Exec specifies the action to take.
httpGet <Object>
HTTPGet specifies the http request to perform.
tcpSocket <Object>
Deprecated. TCPSocket is NOT supported as a LifecycleHandler and kept for
the backward compatibility. There are no validation of this field and
lifecycle hooks will fail in runtime when tcp handler is specified.
kubectl explain pod.spec.containers.lifecycle.postStart.exec
KIND: Pod
VERSION: v1
RESOURCE: exec <Object>
DESCRIPTION:
Exec specifies the action to take.
ExecAction describes a "run in container" action.
FIELDS:
command <[]string>
Command is the command line to execute inside the container, the working
directory for the command is root ('/') in the container's filesystem. The
command is simply exec'd, it is not run inside a shell, so traditional
shell instructions ('|', etc) won't work. To use a shell, you need to
explicitly call out to that shell. Exit status of 0 is treated as
live/healthy and non-zero is unhealthy.
[root@k8s-master1 pod]# cat nginx-pod-3.yml
apiVersion: v1
kind: Pod
metadata:
name: nginx-4
spec:
containers:
- name: nginx
image: images.guoguo.com/apps/ubuntu-nginx:1.24.0
ports:
- containerPort: 80
startupProbe:
tcpSocket:
port: 80
initialDelaySeconds: 10
timeoutSeconds: 2
failureThreshold: 2
successThreshold: 1
periodSeconds: 5
readinessProbe:
httpGet:
port: 80
path: /index.html
initialDelaySeconds: 10
timeoutSeconds: 2
failureThreshold: 2
successThreshold: 1
periodSeconds: 5
livenessProbe:
tcpSocket:
port: 80
initialDelaySeconds: 10
timeoutSeconds: 2
failureThreshold: 2
successThreshold: 1
periodSeconds: 5
lifecycle: #生命周期 也就是这俩钩子的爹
postStart: #容器创建后执行的
exec: #命令行
command: ['/bin/bash','-c','mkdir /apps/data'] #必须找个格式 使用/bin/bash -c 用mkdir 创建/apps/data目录
preStop: #容器结束前执行的 语法和postStart一样
exec:
command: [ '/bin/bash','-c','sleep 10'] #睡眠十秒
restartPolicy: Always #pod重启策略 Always 不管咋样 都要重启创建
[root@k8s-master1 pod]# kubectl apply -f nginx-pod-3.yml
pod/nginx-4 created
[root@k8s-master1 pod]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-4 1/1 Running 0 25s然后我们看下pod里面看看/apps下有没有创建data目录
[root@k8s-master1 pod]# kubectl exec nginx-4 -- ls -d /apps/data
/apps/data
#创建了data目录