Containerization (Docker & Kubernetes)

A virtual machine virtualizes an entire operating system, including its heavy kernel, requiring gigabytes of storage and memory for each instance. In contrast, a Docker container shares the host operating system's kernel, making it incredibly lightweight and allowing hundreds of containers to run simultaneously on a single machine.

While Docker packages and runs a single application, Kubernetes is an orchestration system that manages clusters of hundreds or thousands of those containers across multiple servers. It automatically restarts crashed containers, balances web traffic loads, and scales application resources up or down based on real-time user demand.

A Pod is the smallest and most basic deployable computing object in the Kubernetes architecture. Instead of running containers directly, Kubernetes places one or more tightly coupled application containers inside a single Pod, ensuring they share the same network IP address and storage resources on that specific node.

Because Docker containers are designed to be destroyed and recreated at a moment's notice, any data saved inside the container's local file system is permanently lost upon deletion. To prevent data loss, you must use Docker Volumes or bind mounts, which map a directory on the physical host server directly into the container.