Lifecycle and hooks that are offered for Pods (and Containers) are points where your code can take actions. Kubernetes offers a number of places where you can provide explicit feedback to the system to have it operate as you’d like.

The lifecycle of a Pod is an aggregate of several components, as a Pod has a number of moving parts that can be in a variety of states as it operates. The representation of the lifecycle is how Kubernetes manages running your code for you, in conjunction with the control and feedback loops that work from the various controllers.

The states of a Pod's lifecycle are:

• Pending: The Pod has been created through the API, and is in the process of being scheduled, loaded, and run on one of the Nodes
• Running: The Pod is fully operational and the software is running within the cluster
• Succeeded (or) Failed: The Pod has finished operation (normally or crashed)
• Unknown: It occurs fairly rare, and it's typically seen when there’s a problem internal to Kubernetes. In an example, K8s doesn’t know the current state of containers, or is unable to communicate with its underlying systems to determine that state

Based on „Kubernetes for Developers by Joseph Heck“

Daniel Garavaldi