Master Kubernetes Basics: Nodes, Pods, Deployments, and Ingress Explained

Kubernetes has quickly become the new standard for deploying and managing software in cloud environments, though its powerful features come with a steep learning curve.

Hardware

(1) Node

A Node is the smallest unit of compute resources, representing a single machine in the cluster, which can be a physical server, a virtual machine in the cloud, or other resources. Nodes abstract CPU and RAM, so users need not worry about specific machine characteristics.

(2) Cluster

A Cluster aggregates multiple Nodes into a powerful machine. When you deploy applications to a Cluster, it intelligently assigns work to specific Nodes. If Nodes are added or removed, the Cluster automatically redistributes workloads without requiring code changes.

(3) Persistent Volumes

Since applications can move between Nodes, they cannot rely on a Node’s local filesystem for data storage. Kubernetes provides Persistent Volumes, a plugin‑like resource that mounts to the cluster independent of any specific Node, ensuring data persists.

Software

(1) Container

Programs running on Kubernetes are packaged as Linux containers. Containerization creates isolated execution environments, bundling an application with all its dependencies into a single image that can be shared and run with minimal configuration, enabling powerful CI/CD pipelines.

(2) Pod

Kubernetes does not run containers directly; it wraps one or more containers into a higher‑level structure called a pod. Containers within the same Pod share resources and network, can communicate freely, and Pods serve as the replication unit for scaling and load balancing.

(3) Deployment

Deployments provide an abstraction layer to manage Pods. A Deployment declares the desired number of Pod replicas; when added to the Cluster, it automatically launches the required Pods, monitors them, and recreates any that fail, relieving users from manual Pod management.

(4) Ingress

While Pods are isolated from the outside world, an Ingress creates a communication channel that allows external traffic to reach services running inside Pods, enabling access to your applications.

Summary

This article is a translation and compilation from the original Medium post “Kubernetes 101: Pods, Nodes, Containers, and Clusters”.