外贸网站怎么推广,网页建设网站代码,怎么做网站平台梦想,微信小程序商城模板源码在现实场景中#xff0c;我们为了降低业务耦合#xff0c;往往会将一个大大的功能拆解成若干独立的小功能。比如主要业务启动前#xff0c;需要将其所依赖的各种资源都拉下来。一种做法是在一个Pod内完成上述两步操作#xff0c;但是会导致业务逻辑不够独立#xff1b;另外…在现实场景中我们为了降低业务耦合往往会将一个大大的功能拆解成若干独立的小功能。比如主要业务启动前需要将其所依赖的各种资源都拉下来。一种做法是在一个Pod内完成上述两步操作但是会导致业务逻辑不够独立另外一种做法就是启动一个Pod专门用于拉取资源待其完成后再启动业务Pod。
错误的示例
下面部署的Pod将启动3个容器。前两个运行的容器只在/data/whoami追加了一行文本后就退出了。
# common-container.yaml
apiVersion: apps/v1
kind: Deployment
metadata:name: common-container-deployment
spec:replicas: 1selector:matchLabels:app: common-containertemplate:metadata:labels:app: common-containerspec:containers:- name: common-container-1image: busyboxcommand: [/bin/sh, -c, echo \this is init-common-container1\; echo \this is init-common-container-1\ /data/whoami]volumeMounts:- name: emptydir-volumemountPath: /data- name: common-container-2image: busyboxcommand: [/bin/sh, -c, echo \this is init-common-container2\; echo \this is init-common-container-2\ /data/whoami]volumeMounts:- name: emptydir-volumemountPath: /data- name: common-containerimage: busyboxcommand: [/bin/sh, -c, while true; do cat /data/whoami; sleep 5; done]volumeMounts:- name: emptydir-volumemountPath: /datavolumes:- name: emptydir-volumeemptyDir: medium: MemorysizeLimit: 1Gi查看Pod状态可以发现Pod因为前两个容器中脚本执行结束后没有了前台进程容器就退出了。进而导致Pod创建失败。
kubectl get podNAME READY STATUS RESTARTS AGE
common-container-deployment-5569564499-qchgq 1/3 CrashLoopBackOff 4 (7s ago) 40skubectl describe pod common-container-deployment-5569564499-qchgq ……
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal Scheduled 17s default-scheduler Successfully assigned default/common-container-deployment-5569564499-qchgq to ubuntubNormal Pulled 15s kubelet Successfully pulled image busybox in 2.257083309s (2.257101009s including waiting)Normal Pulled 13s kubelet Successfully pulled image busybox in 2.260848562s (2.260857362s including waiting)Normal Pulling 13s kubelet Pulling image busyboxNormal Pulled 11s kubelet Successfully pulled image busybox in 1.989747468s (1.989754568s including waiting)Normal Created 11s kubelet Created container common-containerNormal Started 10s kubelet Started container common-containerNormal Pulling 10s (x2 over 17s) kubelet Pulling image busyboxNormal Pulled 8s kubelet Successfully pulled image busybox in 2.033723483s (2.033734083s including waiting)Normal Created 8s (x2 over 15s) kubelet Created container common-container-1Normal Started 8s (x2 over 15s) kubelet Started container common-container-1Normal Pulling 8s (x2 over 15s) kubelet Pulling image busyboxNormal Pulled 6s kubelet Successfully pulled image busybox in 2.032193623s (2.032200723s including waiting)Normal Created 6s (x2 over 13s) kubelet Created container common-container-2Normal Started 6s (x2 over 13s) kubelet Started container common-container-2Warning BackOff 4s (x2 over 5s) kubelet Back-off restarting failed container common-container-1 in pod common-container-deployment-5569564499-qchgq_default(fd19ae72-5fd0-420d-9931-0d976175cf77)Warning BackOff 4s (x2 over 5s) kubelet Back-off restarting failed container common-container-2 in pod common-container-deployment-5569564499-qchgq_default(fd19ae72-5fd0-420d-9931-0d976175cf77)正确的示例
我们将需要一次性运行结束后可以退出的容器使用initContainers描述。
# init_container.yaml
apiVersion: apps/v1
kind: Deployment
metadata:name: init-container
spec:replicas: 1selector:matchLabels:app: init-containertemplate:metadata:labels:app: init-containerspec:initContainers:- name: init-container-1image: busyboxcommand: [/bin/sh, -c, echo \this is init-container-1\; echo \this is init-container-1\ /data/whoami]volumeMounts:- name: emptydir-volumemountPath: /data- name: init-container-2image: busyboxcommand: [/bin/sh, -c, echo \this is init-container-2\; echo \this is init-container-2\ /data/whoami]volumeMounts:- name: emptydir-volumemountPath: /datacontainers:- name: init-containerimage: busyboxcommand: [/bin/sh, -c, while true; do cat /data/whoami; sleep 5; done]volumeMounts:- name: emptydir-volumemountPath: /datavolumes:- name: emptydir-volumeemptyDir: medium: MemorysizeLimit: 1Gi查看Pod状态可以发现已处于运行状态。说明Pod创建成功了。
kubectl get podNAME READY STATUS RESTARTS AGE
init-container-55c6d46676-5knwk 1/1 Running 0 33s使用initContainers描述的容器已经无法连接只有最后一个有前台程序的容器在运行。
kubectl logs pods/init-container-55c6d46676-5knwk init-container1error: container init-container1 is not valid for pod init-container-55c6d46676-5knwk kubectl logs pods/init-container-55c6d46676-5knwk init-container2error: container init-container2 is not valid for pod init-container-55c6d46676-5knwk kubectl logs pods/init-container-55c6d46676-5knwk init-containerthis is init-container-1 this is init-container-2 总结
初始化容器用于运行一次就可以退出的业务场景而普通容器则要一直有前台程序在运行。
