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Overview
Finally, we managed to come to the atomic unit in Kubernetes: Pods. But what is a pod ? Well it is simple:
- Hypervisors have VM
- Docker have Containers
- Kuberenets have Pods
You can think of a pod of something between container and a VM. Unlike VM they are mortal, when they die, we just bring a new one, unlike containers though, they have IPs. Generally a pod has a single container in it, but there are exceptions.
Lifecycle
The lifecycle of a pod is the following:
- We present a manifest file to the API server
- The api server loads the containers, download, install, all that crap and puts it in “pending” state
- If it doesn't fail it is put in “Running state”
- Again if it doesn't fail it is put in “Succeeded” state
- If it fails in any of the previous state, it is put in: “Failed state” and we have to inspect our manifest fail or whatnot. WE DON'T WORK WITH THE FAILED PODS, WE DON'T CARE, THEY ARE DEAD, FINITO :)
Here is a picture for visual reference: