Unlocking Kubernetes Architecture: From Pods to High‑Availability Design

Overview

Kubernetes (k8s) is an open‑source platform for automated container operations, including deployment, scheduling, and scaling across nodes.

Key Functions

Automated container deployment and replication.

Real‑time elastic scaling of container workloads.

Container orchestration with built‑in load balancing.

Core Components

kubectl – command‑line client.

kube‑apiserver – REST API entry point.

kube‑controller‑manager – runs background control loops.

kube‑scheduler – assigns Pods to nodes.

etcd – highly available key‑value store for configuration and service discovery.

kube‑proxy – network proxy on each node.

kubelet – node‑level agent that manages Pods.

DNS – optional service for creating DNS records for Services.

Architecture Highlights

Typical deployment includes a local production center, a local disaster‑recovery center, and an off‑site disaster‑recovery center, with etcd providing strong consistency.

Service Discovery

K8s supports two native mechanisms: environment‑variable injection (limited) and DNS via the kube‑dns add‑on.

Pod Shared Resources

Containers in the same Pod share PID, network, IPC, UTS namespaces and Volumes, enabling localhost communication.

CNI Plugins

Common CNI (Container Network Interface) plugins provide standardized networking and resource cleanup for containers.

Load Balancing Layers

Layer 2 – MAC‑based load balancing.

Layer 3 – IP‑based load balancing.

Layer 4 – IP + port load balancing.

Layer 7 – URL/application‑level load balancing (Ingress).

Isolation Dimensions

Network Model Principles

Each Pod receives a unique IP address (IP‑per‑Pod model), allowing flat, directly reachable networking across the cluster without NAT.