Getting Started with Docker – Containers, Images & the Basics

🎯 Whether you’re just exploring containers or preparing for real-world DevOps, this guide will set the stage.

Table of Contents

🔧 Installation

Before we begin, install Docker on your system:

👉 Click here to visit the official Docker installation page

🐳 What is Docker? Why Use It?

Docker is an open-source platform that allows you to package, distribute, and run applications in isolated environments called containers.

It provides a standardized way to ensure software runs consistently across different environments. Everything runs in a lightweight, portable package — making development, testing, and deployment faster and more reliable.

🧱 Containers vs Virtual Machines

🧠 Docker Architecture

Docker is made up of the following components:

• Docker Engine: Core runtime environment.
• Docker CLI: Command-line interface to communicate with the engine.
• Docker Daemon (dockerd): Background service handling containers and images.
• Docker Hub: A registry for sharing and downloading Docker images.
• Images & Containers: Blueprints vs instances.

🛠️ Key Docker Components

🔹 Images

• Immutable blueprint of an application.
• Versioned and portable.
• Pulled from registries like Docker Hub.

🔹 Containers

• Running instances of images.
• Isolated environments for applications.
• Can be started, stopped, restarted, or deleted.

🔹 Volumes

• Used for data persistence.
• Exist outside the container’s filesystem.

🔹 Networks

• Allow inter-container communication.
• Default types: bridge, host, and none.

🧾 What is a Dockerfile?

A Dockerfile is a text-based script of instructions for building a Docker image.

Example:

FROM python:3.11
WORKDIR /app
COPY . .
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

⚙️ Useful Docker Commands & Flags

🔍 Check Version & System Info

docker --version
docker info

📥 Pulling an Image

docker pull alpine

Downloads the Alpine base image.

🚀 Running a Container

Interactive shell inside Alpine:

docker run -it alpine sh

Running an nginx container on port 8080:

docker run -d -p 8080:80 --name web nginx

Common flags:

• -d: Detached mode
• -p: Port mapping (host:container)
• --name: Custom container name
• --rm: Auto-remove on exit
• -v: Mount a volume

📋 Managing Containers

List containers:

docker ps        # Running only
docker ps -a     # All, including stopped

Stop, start, remove containers:

docker stop mycontainer
docker start mycontainer
docker rm mycontainer

📦 Working with Images

List all images:

docker images

Remove an image:

docker rmi nginx

🧭 What’s Next?

In the next part, we’ll explore how to build your own Docker images using Dockerfiles, manage image layers efficiently, and follow best practices for optimized builds.

Stay tuned for Part 2: Building Docker Images Like a Pro.

🧠 Extra Learning: Read official Docker docs for deeper reference.