Getting Started with Docker: A Beginner’s Guide

In today's fast-paced development environment, containerization has become an essential part of software deployment strategies. Tools like Docker simplify this process by allowing developers to package applications and their dependencies into lightweight, portable containers. By the end of this tutorial, you will be able to create and run your first Docker container.

Prerequisites

Before diving in, make sure you have a basic understanding of what Docker is and why it’s useful for development workflows. Familiarity with command-line operations on your local machine is also helpful.

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Step 1: Install Docker on Your System

The first step in using Docker is to install it on your local machine. The installation process varies slightly depending on your operating system, but the official Docker documentation provides comprehensive guides for each platform.

Installing Docker on Ubuntu

To install Docker on an Ubuntu system, follow these steps:

Update your existing package index:

sh
   sudo apt-get update
   

Install required packages to allow apt to use a repository over HTTPS:

sh
   sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
   

Add Docker’s official GPG key:

sh
   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
   

Set up the stable repository:

sh
   echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
   

Update the package index again and install Docker:

sh
   sudo apt-get update && sudo apt-get install docker-ce docker-ce-cli containerd.io
   

Verify that Docker is installed correctly by running the hello-world image:

sh
   sudo docker run --rm hello-world
   

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Step 2: Create a Basic Dockerfile

A Dockerfile is a text document that contains all the commands you need to build a Docker image. It’s a script for Docker, telling it how to create an environment.

Example Dockerfile

Here’s a basic example of what a Dockerfile might look like:

docker
Example Dockerfile
FROM python:3.8-slim
WORKDIR /app
COPY . /
RUN pip install -r requirements.txt
CMD [ "python", "/app/app.py" ]

FROM: Specifies the base image to use.

WORKDIR: Sets the working directory inside the container.

COPY: Copies files from your local machine into the Docker image.

RUN: Executes commands during the build process.

CMD: Defines the default command for running a container.

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Step 3: Build and Run a Docker Image

Once you have created your Dockerfile, you can build an image using it. Then, you can run that image as a container.

Building and Running a Container

Build the Docker image from the Dockerfile:

sh
   docker build -t my-python-app .
   

Run the container:

sh
   docker run -p 4000:80 my-python-app
   

The -p flag maps a port on your host machine (4000) to the same port in the Docker container.

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Step 4: Explore the Benefits of Using Containers

Containers offer several advantages over traditional deployment methods, including:

Isolation: Each application runs in its own environment, isolated from others.

Portability: Applications and their dependencies are packaged together, making them easy to move between environments.

Consistency: Ensures the same runtime environment across development, testing, and production.

Conclusion

By following this tutorial, you have set up Docker on your local machine, created a simple Dockerfile, built an image, and run it as a container. This foundational knowledge can help streamline your software deployment process.

If you'd like help with setting up or optimizing containers for your project, Stackrunner builds robust cloud & DevOps solutions to support you. Dive into more engineering insights on our blog or reach out about your project.

cloud & DevOps

Sources:

5 Fun Docker Projects for Absolute Beginners

Docker for Beginners in 2026: Containerization Explained (With Hands-On Examples)