要先了解 kubernetes 的三个 object type, Pods Deployment Service.
Pods-runs one or more closely related containersDeployment-sets up networking in a Kubernetes clusterService-Maintains a set of identical pods, ensuring that they have the correct config and that the right number of them exist.
deployment 有非常关键的一点 Monitors the state of each pod, updating as necessary.
一个pods虽然能包含多个containers, 但是缺乏pods对containers的监控, 使container保持alive的状态. deployment object 可以监控每个pod的状态, keep the replicas(pods) alive.
Pods可能被killed, 并且也不能依赖这些Pods的IP地址, 因为这些IP地址不是持久的。这时候我们需要Service Object.
Service object (that is like a grouping object and gives it a so-called virtual IP (cluster IP) for the pods that have a certain label - and those pods are basically the app containers that you deployed with the former deployment object).
日程使用中我们一般不用Pod，而是使用Deployment和Service来部署。
