🚀 Kubernetes Architecture Explained.

#devops #containers #kubernetes #architecture

Containers revolutionized software delivery — fast, portable, and reliable.

But managing hundreds of containers across servers? That’s where Kubernetes (K8s) comes in.

Let’s explore the complete architecture of Kubernetes, why it’s used, and how it powers modern cloud infrastructure. 🌩️

🧠 What is Kubernetes?

Kubernetes (K8s) is an open-source container orchestration platform originally developed by Google and now maintained by the Cloud Native Computing Foundation (CNCF).

It automates:

🧩 Deployment of containers
⚙️ Scaling and load balancing
🛠️ Self-healing and rolling updates
🔐 Configuration and secrets management

In short:

Kubernetes ensures your containerized applications run exactly as intended — automatically and reliably.

🧩 Kubernetes Core Architecture Overview

Kubernetes is built on two major layers:

Control Plane (Master) → Brains of the cluster
Worker Nodes → Muscles that actually run workloads

Let’s break them down 👇

🧠 1️⃣ Control Plane (Master Components)

These components manage the overall cluster state.

Component	Description
API Server (`kube-apiserver`)	The front door of the cluster. Handles REST requests, validates configuration, and updates the cluster state in `etcd`.
etcd	A distributed key-value store that holds all cluster data (desired & current state). Acts as the source of truth.
Scheduler (`kube-scheduler`)	Decides which node runs a new Pod based on available resources and policies.
Controller Manager (`kube-controller-manager`)	Ensures the cluster matches the desired configuration (e.g., if a Pod fails, it starts a new one).
Cloud Controller Manager	Connects Kubernetes with underlying cloud services like load balancers and storage.

💪 2️⃣ Worker Nodes (Data Plane)

Worker nodes actually run your containers.

Each node runs the following key components:

Component	Description
Kubelet	Node agent that ensures containers are running as per the API server’s instructions.
Kube Proxy	Manages networking, traffic routing, and load balancing between services.
Container Runtime	Runs containers (e.g., Docker, containerd, CRI-O). Responsible for pulling images and starting containers.

🧱 3️⃣ Kubernetes Objects

Kubernetes uses declarative configuration files (YAML) to manage workloads.

Object	Description
Pod 🧫	The smallest deployable unit; runs one or more containers together.
ReplicaSet 🔁	Ensures the desired number of identical Pods are always running.
Deployment 🚀	Manages rollout, rollback, and scaling of applications.
Service 🔗	Provides stable networking and load balancing between Pods.
ConfigMap / Secret 🔐	Externalize configuration and sensitive data.
Ingress 🌍	Routes external HTTP(S) traffic to internal services.
Namespace 📦	Organizes cluster resources logically for isolation.

🏗️ 6️⃣ Kubernetes Architecture Diagram (Text View)



               ┌──────────────────────────┐
               │     Load Balancer (LB)   │
               └──────────────┬───────────┘
                              │
         ┌────────────────────┴──────────────────────┐
         │            Control Plane Nodes            │
         │ (API Server, etcd, Scheduler, Controllers)│
         └────────────────────┬──────────────────────┘
                              │
         ┌────────────────────┴──────────────────────┐
         │              Worker Nodes                 │
         │ (Kubelet, Kube Proxy, Containers/Pods)    │
         └────────────────────┬──────────────────────┘
                              │
                ┌─────────────┴─────────────┐
                │     Services & Ingress    │
                └─────────────┬─────────────┘
                              │
                        User Traffic 🌍