红帽全球峰会5.3. 镜像拉取（pull）策略
Pod 中的每个容器均有容器镜像。在创建了镜像并将其推送（push）到 registry 后，即可在 Pod 中引用它。
5.3.1. 镜像拉取（pull）策略概述
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当 Red Hat OpenShift Service on AWS 经典架构创建容器时，它会使用容器 imagePullPolicy 来决定是否应在启动容器前拉取(pull)镜像。imagePullPolicy 有三个可能的值：
| 值 | 描述 |
|---|---|
|
| 始终拉取（pull）镜像。 |
|
| 仅拉取（pull）节点上不存在的镜像。 |
|
| 永不拉取（pull）镜像。 |
如果没有指定容器 imagePullPolicy 参数，Red Hat OpenShift Service on AWS 经典架构会根据镜像标签设置它：
-
如果标签
是最新的，Red Hat OpenShift Service on AWS 经典架构会将imagePullPolicy默认设置为Always。 -
否则，Red Hat OpenShift Service on AWS 经典架构将
imagePullPolicy默认设置为IfNotPresent。
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