Docker Architecture

3. Docker Architecture

🏗️ How Docker Works Internally

Docker uses a client-server architecture:

Docker Client — The CLI tool you use (docker run, docker build)
Docker Daemon (dockerd) — The background service that does all the actual work
Docker Engine — The combination of client + daemon
Docker Registry — A storage system for Docker images (like GitHub for code)
Docker Hub — Docker’s official public registry

🗺️ Docker Architecture Diagram

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  <text x="340" y="280" text-anchor="middle" font-size="10" fill="#33691e">cache</text>
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🔍 Component Breakdown

Docker Client

The CLI tool you interact with
Sends commands to the Docker daemon via REST API
Can connect to local or remote daemons

Docker Daemon (dockerd)

Background service running on your machine
Manages images, containers, volumes, and networks
Does the actual “work” of Docker

Docker Engine

The complete system = Client + Daemon
Available for Linux, macOS (via VM), Windows (via WSL2)

Docker Registry

A server that stores Docker images
Docker Hub is the public default
You can run private registries (e.g., Harbor, AWS ECR)

Docker Hub

Like GitHub, but for Docker images
Contains millions of public images
URL: hub.docker.com