Kubernetes Architecture Overview

What is Kubernetes?

Kubernetes (or K8s) is an open-source developed by Google for container management. It can deploy on vary platform (On-premise, Cloud, Virtual Machine). Many large companies use it for system deployment and management.

Why is Kubernetes?

We have several popular ways to deploy application

• Traditional

• Virtualized

• Container

Each approach has its advantages and disadvantages. Here, I will focus on the third approach (Container), which is more popular than the others. For a simple term, think of your server as a ship, and each container it carries is an isolated application ready to be deployed. Sound great, but we have another problem:

• How we manage it? 🤔
• How we scale it? 🤨
• What happen if the "ship" drown? 😱

When we're anxious to find a solution, Google offers helpful solution - Kubernetes 😎

How Kubernetes work?

Kubernetes enables application grouping and management via namespaces, and its Services facilitate traffic routing to the correct applications. When a "ship" drown, it move our container to another "ship" to ensure high availability for the app. And many, many things we can work on it. And here is the "secret" behind it - architecture

Control plane (Master node)

It responsible for application management and high availability (HA). We never run application on it.

API Server

• Kubernetes's heart
• All components must communicate through it, not directly.

Control manager

• It contain vary controller for each purpose (deployment, services, storage, etc.)

Cloud control manager

• Only appear on cloud platform

Scheduler

• Resource coordinator

etcd

• A database stores the cluster's state, including configurations, node data, pod data, and service data.

P/s: Backing up etcd is crucial for Kubernetes availability.

Node (Worker node)

The application will run inside this; the number of worker nodes is limited only by your budget.

And worker node have 3 mains components:

Container Runtime Interface (CRI)

• Run container (docker, containerd or something else)
• A CRI contains one or more pods, each representing an application

Kubelet

• Receive and execute from API Server
• Transmit system information to API server
• Ensure containers/pods run correct state
• Continuously report pod/node status to the control plane and manage the pod lifecycle on the node

Kubernetes Service Proxy

• Maintain network rules for pod connectivity within and outside the cluster

Conclusion

We have go through the Kubernetes architecture and know what is it. In the next post, I will guide you install and run Kubernetes with on-premise system.

Happy Coding!