Docker Architecture & Essential Commands

🧱 Docker Architecture Overview

Before diving into commands, it’s important to understand how Docker works internally.

Docker follows a client-server architecture consisting of three main components:

1. Docker Client:
   • The CLI (command-line interface) that you use to run Docker commands (e.g., docker build, docker run).
   • These commands are sent to the Docker Daemon.
2. Docker Daemon (dockerd):
   • The background service that builds, runs, and manages containers.
   • It listens for Docker API requests and interacts with images, containers, networks, and volumes.
3. Docker Registry:
   • A centralized place where Docker images are stored (like Docker Hub).
   • You can push your built images to the registry or pull existing ones for use.

[ Developer (CLI) ] --> [ Docker Daemon ] --> [ Container Runtime / Registry ]

Each container runs as an isolated process on your system, sharing the OS kernel but having its own filesystem, network, and process space.

⚙️ Key Dockerfile Commands

1. FROM – Define Base Image

• The FROM instruction sets the base image for your Docker image.
• Every Dockerfile must start with a FROM statement.

Example:

FROM python:3.10

Explanation:

This means our container will start from an official Python 3.10 image that already includes Python installed.

Real-life example:

If you're building a Django web app, using FROM python:3.10 saves you from manually installing Python inside the container.