Docker Architecture

Docker consists of multiple components working together.

Main components:

• Docker Engine
• Docker CLI
• Docker Images
• Docker Containers
• Docker Registry

High-Level Architecture

+-----------------------------------+
| Docker CLI                        |
| docker run / docker ps / etc.     |
+-----------------------------------+
                ↓
+-----------------------------------+
| Docker Engine (dockerd)           |
+-----------------------------------+
                ↓
+-----------------------------------+
| Containers / Images / Networks    |
+-----------------------------------+

Docker Engine

Docker Engine is the backend service responsible for:

• creating containers
• managing images
• networking
• storage
• container lifecycle

Main service:

dockerd

Docker CLI

The Docker CLI is the command-line interface.

Examples:

docker ps
docker images
docker run nginx

The CLI communicates with Docker Engine.

Docker Registry

Docker images are usually downloaded from registries.

Most common registry:

Docker Hub

Example:

docker pull nginx

Docker downloads the image automatically.

Docker Workflow

Simplified workflow:

Dockerfile
    ↓
Docker Image
    ↓
Docker Container