Docker

A Dockerfile is a text file with instructions that tell Docker how to build your image. Every Docker image — from nginx to postgres to your own app — starts with a Dockerfile. In this tutorial, you will learn every key Dockerfile instruction and write a complete, production-ready Dockerfile. Dockerfile Basics A Dockerfile is a plain text file named Dockerfile (no extension). Docker reads it top to bottom when building an image. Each instruction creates a new layer. ...

Docker has two core concepts you must understand before anything else: images and containers. Beginners often confuse them. Once you understand the difference, everything else in Docker makes sense. What is a Docker Image? A Docker image is a read-only template. It contains everything your application needs to run: the OS filesystem, libraries, dependencies, and your application code. An image is built from a Dockerfile. Think of an image like a class in object-oriented programming. It defines what a container will look like. ...

Before you can run any containers, you need to install Docker. This tutorial covers every installation option: Docker Desktop for macOS and Windows, and Docker Engine for Linux servers. Last updated: June 2026. Docker pricing and features change frequently. Always check docker.com/pricing for the latest information. Docker Desktop vs Docker Engine There are two main ways to run Docker: Docker Desktop is a GUI application for macOS and Windows. It includes Docker Engine, Docker CLI, Docker Compose, built-in Kubernetes, and a visual dashboard. It is the easiest way to get started. ...

Docker is the most popular containerization tool in the world. According to the 2025 Stack Overflow Developer Survey, Docker is one of the most widely used tools among professional developers, with usage continuing to grow year-over-year. But what is Docker? And how is it different from a virtual machine? In this tutorial, you will learn what Docker is, how containers work, and why developers use Docker for everything from local development to production deployments. ...

This is the final article in the DevTools series. In the previous 17 articles, you learned Git, Docker, and SQL separately. Now you will use all three together to build and deploy a real project. We will build a simple task management API with a PostgreSQL database. You will set up a Git repository with feature branches, write the API, Dockerize everything, add a CI/CD pipeline with GitHub Actions, and deploy it to a server. ...

In the previous tutorials, we learned how to build images, run containers, use Compose, and manage volumes and networks. Everything so far happened on your local computer. Now it is time to deploy. In this tutorial, you will learn how to move your application from your laptop to a production server. The Deployment Workflow Deploying with Docker follows a simple pattern: Build the image on your computer (or in CI/CD) Push the image to a registry Pull the image on the server Run the container on the server Your Computer Registry Server ┌──────────┐ ┌──────────────┐ ┌──────────┐ │ Build │────►│ Docker Hub │────►│ Pull │ │ Image │push │ or ghcr.io │pull │ & Run │ └──────────┘ └──────────────┘ └──────────┘ Docker Hub — The Default Registry Docker Hub is the default place to store and share images. It is free for public images and offers one private repository on the free plan. ...

In the previous tutorial, we used Docker Compose to run an app with a database. We briefly mentioned volumes and networking. Now let’s understand them properly. These two topics answer two important questions: Volumes: How do I keep data when a container is removed? Networking: How do containers talk to each other? Why Containers Lose Data Containers are designed to be temporary. You can create them, destroy them, and replace them. This is a feature, not a bug — it makes containers predictable and easy to deploy. ...

In the previous tutorial, we learned how to build a Docker image for a single application. But most real applications need more than one service. A web app might need a database. An API might need a cache. A backend might need a message queue. Running each service with docker run and connecting them manually is tedious. Docker Compose solves this. It lets you define all your services in one file and start everything with a single command. ...

In the previous tutorial, we ran containers from pre-built images like ubuntu and nginx. That is useful, but in real projects you need to package your own application into an image. That is what a Dockerfile does. A Dockerfile is a text file with instructions that tell Docker how to build an image. Think of it as a recipe — each line is a step. Your First Dockerfile Let’s create a simple Node.js application and package it with Docker. ...

You write an app. It works on your computer. You send it to a friend. It does not work on their computer. They have a different operating system, a different version of Python, or missing libraries. This is the classic “it works on my machine” problem. Docker solves it. What Is Docker? Docker is a tool that packages your application and everything it needs into a container. A container includes your code, libraries, system tools, and settings. It runs the same way everywhere — on your laptop, your colleague’s laptop, or a server in the cloud. ...