【云原生 | 从零开始学Kubernetes】十二、k8spod的生命周期与容器钩子 - ToB企服应用市场:ToB评测及商务社交产业平台

[root@k8smaster node]# vim init.yaml
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
labels:
app: myapp
spec:
containers:
- name: myapp-container
image: busybox:1.28
command: ['sh', '-c', 'echo The app is running! && sleep 3600']
initContainers:
- name: init-myservice
image: busybox:1.28
command: ['sh', '-c', "until nslookup myservice.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for myservice; sleep 2; done"]
- name: init-mydb
image: busybox:1.28
command: ['sh', '-c', "until nslookup mydb.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local; do echo waiting for mydb; sleep 2; done"]
#上面两段长的是myservice的svc和mydb的svc
[root@k8smaster node]# kubectl apply -f init.yaml
pod/myapp-pod created
[root@k8smaster node]# kubectl get pods
NAME READY STATUS RESTARTS AGE
myapp-pod 0/1 Init:0/2 0 7s
#发现一直在初始化，查看一下日志
[root@k8smaster node]# kubectl logs myapp-pod
Error from server (BadRequest): container "myapp-container" in pod "myapp-pod" is waiting to start: PodInitializing
#有个container是waiting状态，去yaml看看
until nslookup myservice.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local;
#这是在解析myservice的svc，解析到才成功，不然就会一直循环，我们没有创建，所以一直卡在这里！
[root@k8smaster node]# vim service.yaml
---
apiVersion: v1
kind: Service
metadata:
name: myservice
spec:
ports:
- protocol: TCP
port: 80
targetPort: 9376
---
apiVersion: v1
kind: Service
metadata:
name: mydb
spec:
ports:
- protocol: TCP
port: 80
targetPort: 9377
[root@k8smaster node]# kubectl apply -f service.yaml
service/myservice created
service/mydb created
[root@k8smaster node]# kubectl get pods
NAME READY STATUS RESTARTS AGE
myapp-pod 1/1 Running 0 4m46s
#成功启动
[root@k8smaster node]# kubectl logs myapp-pod
The app is running!
[root@k8smaster node]# kubectl describe pods myapp-pod
#也可以看启动了哪些容器在下面

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......
containers:
- image: sample
name: war
lifecycle：
postStart: #钩子
exec:
command: #命令
- “cp”
- “/sample.war”
- “/app”
prestop: #钩子
httpGet: #httpget的探针
host: monitor.com
path: /waring
port: 8080
scheme: HTTP
......
以上示例中，定义了一个 Pod，包含一个 JAVA 的 web 应用容器，其中设置了 PostStart
和PreStop 回调函数。即在容器创建成功后，复制/sample.war 到/app 文件夹中。而在容器
终止之前，发送 HTTP 请求到 http://monitor.com:8080/waring，即向监控系统发送警告。
#可以看帮助文档
[root@k8smaster node]# kubectl explain pods.spec.containers.lifecycle

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spec:
containers:
- name: nginx-demo
image: centos:nginx
lifecycle:
preStop: #钩子
exec:
command: ["/usr/local/nginx/sbin/nginx","-s","quit"] #删除之前会先停掉nginx再删除容器
ports:
- name: http
containerPort: 80

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