Kubernetes: Definition, Functions, and Operation Mechanisms

Kubernetes (abbreviated as K8s) is an open-source system used to manage and deploy containerized applications across a computer network. Kubernetes has become a popular and powerful container management platform, originally developed by Google and currently maintained by a large community of developers.

The main functions of Kubernetes include

  1. Container Management: Kubernetes allows you to package applications and their resources into containers. Containers provide a lightweight environment and ensure that applications run consistently on any system.

  2. Automated Deployment: Kubernetes enables automated deployment and easy scalability of applications and services. You can specify resource requirements, the number of instances, and Kubernetes will automatically maintain the desired state.

  3. Resource Management: K8s manages server resources such as CPU, memory, and storage to ensure that applications do not consume excessive resources and do not interfere with each other.

  4. Automatic Recovery and Fault Tolerance: Kubernetes helps applications automatically recover from failures. It can automatically roll back to a previous version of an application if the new version encounters issues.

  5. Load Balancing and Traffic Distribution: Kubernetes provides mechanisms to evenly distribute traffic among instances of applications on different server nodes. This improves performance and ensures scalability.

  6. Configuration and Secrets Management: Kubernetes allows you to securely manage application configuration and secrets using features like K8s Secrets and ConfigMaps.

The operating mechanisms of Kubernetes include

  1. Nodes: The servers or individual computers in the network are referred to as "nodes." There are two types of nodes in Kubernetes: Master Node and Worker Node. The Master Node manages and controls the entire system, while the Worker Node executes containers and applications.

  2. Pods: A Pod is the smallest deployable unit in Kubernetes. A pod can contain one or multiple containers, but they share the same network storage and lifecycle. This facilitates communication between containers within a pod.

  3. Controller: Controllers are components that manage and maintain replicas of pods. Types of controllers include ReplicaSet (ensuring the correct number of pods and restarting if necessary), Deployment (managing versions and updates of applications), and StatefulSet (for deploying stateful applications).

  4. Service: Services are a mechanism for load balancing and distributing traffic to pods. Services make it easy for applications to access pods without needing to know their specific locations.

  5. Kubelet and Kube Proxy: Kubelet is a component running on each worker node, responsible for managing pods on that node. Kube Proxy is a network proxy for connecting to pods.

As a result, Kubernetes automates the deployment and management of containerized applications, reducing the time and effort required to maintain complex systems.