When working with containerized applications, understanding Pods is crucial because they are the entities that Kubernetes manipulates when it comes to scheduling workloads, scaling, and handling different aspects of application lifecycle management.

What Are Kubernetes Pods? 

Kubernetes is an open-source platform designed to automate deploying, scaling, and managing containerized applications. And the Pod is the smallest and simplest unit in the Kubernetes object model that you create or deploy. A Pod encapsulates an application container (or, in some cases, multiple containers), storage resources, a unique network IP, and options that govern how the container(s) should run.

A Pod models an application-specific "logical host" in a Kubernetes cluster - it contains one or more application containers which are relatively tightly coupled. For example, they might be a web server and a supporting database. The containers in a Pod share the same network namespaces, meaning they can communicate with each other using localhost, and can also share the same storage volumes.

Understanding Pods is crucial because they are the entities that Kubernetes manipulates when it comes to scheduling workloads, scaling, and handling different aspects of application lifecycle management. Now that we know what Pods are, let's explore their various statuses.

Understanding the Different Kubernetes Pod Statuses 

A Kubernetes Pod has a PodStatus, which includes an array of PodConditions through which the Pod has or has not passed. The primary Pod statuses are Pending, Running, Succeeded, Failed, and Unknown, and each of these statuses provides essential information about the state of the Pod. Let's explore these Pod statuses one by one.

Pending

When a Pod is in the Pending status, it means that the system has accepted the Pod, but one or more of the required container images has not been created. A Pod remains in the Pending state until all of its containers have been created, at which point it transitions to Running. This status might also indicate that the Pod is waiting for other resources, such as persistent storage, to become available.

Running

Once a Pod has been scheduled on a node, all of its containers are created, and at least one container is in the Running state, the Pod status becomes Running. It's important to note that Running does not necessarily mean that a Pod's applications are up and running, just that they are in the process of starting up.

Succeeded

The Succeeded status indicates that all containers in the Pod have terminated successfully and will not be restarted. This typically means that the tasks or workloads the Pod was responsible for have been completed. After this, the Pod remains in the system for a while, after which it is cleaned up and deleted.

Failed

On the other hand, the Failed status implies that all containers in the Pod have terminated, and at least one container has returned a failure code. This generally means that the tasks the Pod was responsible for were not completed successfully, and the system might either replace the Pod or take other corrective measures.

Unknown

Lastly, the Unknown status is used when the state of the Pod could not be obtained for some reason. This could be due to a communication error between the Kubernetes master and the node where the Pod is running.