Build Your Own Kubernetes: A Small Orchestrator That Teaches the Real System
A container can be started with one command. Keeping the right number of containers running after machines fail, requests race, and processes restart is a different problem. That problem is the useful starting point for building your own Kubernetes. This article first explains why Kubernetes exists and how its real architecture works. It then uses that foundation to build a small container…
Container orchestration with Kubernetes can be built from the ground up by understanding its core components and their roles. The article explains why Kubernetes exists, how its architecture works, and guides you through creating a small container orchestrator. The target reader is a developer familiar with running containers and building web APIs, but with no experience in implementing a control plane.
Kubernetes emerged from Google's experience with Borg, an internal cluster management system. It was open sourced in 2014 and gained the CNCF's backing in 2015. While Borg introduced design principles, Kubernetes operates as a separate project. Both platforms share the goal of managing containerized applications across machines.
A Kubernetes cluster consists of a control plane and worker nodes. The control plane manages cluster state, while nodes run workloads. Components like the API server, etcd, scheduler, controller manager, and workers handle specific tasks. Understanding these components and their interactions is crucial before diving into building a small orchestrator.
Key components include:
1. API server: The centralized entry point for all requests, handling validation and persistence of changes.
2. etcd: A distributed key-value store that holds the cluster's desired state.
3. Scheduler: Assigns Pods to nodes based on resource availability and constraints.
4. Controller manager: Manages various controllers that monitor and maintain cluster health.
5. Worker components: Node agents and kubelets that execute workloads on nodes.
Controllers and node agents continuously reconcile the cluster's desired state with its actual state, ensuring consistency. They handle tasks like placing Pods on nodes, restarting failed containers, and managing resource allocation.
The article emphasizes that understanding Kubernetes' architecture is essential before attempting to build a small orchestrator. It provides a foundation for grasping the roles of the API server, etcd, scheduler, controller manager, and worker components. The goal is to create a local learning system that demonstrates core Kubernetes concepts without replicating the entire API.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
