Pods

Pod is the smallest unit of deployment to interact with in a K8s cluster.

• Can be created/deleted/deployed

• Represents one running process on your cluster

A pod contains:

• Docker application container

• Storage resources

• Unique IP

• Options to govern how containers should run

Features of a pod

• Multiple Docker containers can run in a pod

• Pod represents one single unit, a single instance of the application in K8s

• It is tightly coupled and shares resources.

• Ephemeral, disposable

• Never self starts (by scheduler) or self heals

• Higher level constructs to add pod stability called controllers

Pod States

1. Pending - accepted by K8s system, but container creation is pending

2. Running - scheduled on a node and all of its containers are created, with at least one in running state

3. Succeeded - all containers in the pod have exited with exit status 0 (successful execution, will not be restarted)

4. Failed - all containers in the pod have exited with exit status 0, but one failed with non-zero status

5. CrashLoopBackOff - container fails to start for some reason and K8s tries over n over again to restart