k8s默認會從遠端拉取鏡像，其配置參數imagePullPolicy為Always
containers:
- name: demo
image: image
imagePullPolicy: Never
pod報錯"Back-off restarting failed container"解決辦法
containers:
- name: demo
image: python：3.6
imagePullPolicy: IfNotPresent # 這個設置 會從本地先找，沒有從遠處拉取
command: [ "/bin/bash", "-ce", "tail -f /dev/null" ]