Inside Kubernetes Pods: A Simple Guide to Pod Phases
- Cloud Native Insight
- Sep 11, 2024
- 2 min read
Updated: 2 days ago
Kubernetes is a popular platform used for managing containerised applications and a fundamental concept within Kubernetes is the pod. A pod is the smallest unit in Kubernetes, and it represents one or more containers that run together. Every pod has a life cycle, which is reflected in its phases. These phases indicate the current status of a pod.
Let’s break down the different Kubernetes pod phases in simple terms.
Pod Lifecycle
Imagine you're running an application in a container. Kubernetes groups one or more of these containers into a pod, and the pod goes through different phases depending on what's happening inside.
These phases are:
Pending
Running
Succeeded
Failed
Unknown
Pod Phases Explained
Pod Phase | Description | Example |
|---|---|---|
Pending | The pod has been created but is waiting for resources or downloading container images. | The pod is waiting to download the container image or waiting for node allocation. |
Running | The pod has been scheduled on a node and at least one container is up and running. | The pod is running your application or starting the container. |
Succeeded | All containers in the pod have completed successfully, and the pod has finished its work. | A batch job finishes successfully, and the pod exits. |
Failed | The pod has terminated, and one or more containers in the pod have failed due to errors. | The application in the pod crashes due to an error. |
Unknown | The state of the pod cannot be determined due to communication issues between Kubernetes and the node. | Kubernetes is unable to contact the node running the pod. |
Why does this matter?
Understanding the different pod phases helps you monitor and troubleshoot your Kubernetes environment easier. Whether you're deploying a new application or running batch jobs, knowing what phase your pod is in can help you ensure that everything runs smoothly, or help you identify and resolve issues quickly when things go wrong. This also will help you match monitoring and alerting if you are using Prometheus and Grafana.