Docker

“Works on my machine” is a classic developer problem. One developer runs Python 3.11, another runs 3.13. One uses PostgreSQL 15, another uses 16. The app behaves differently on every machine. Docker solves this. With Docker, your entire development environment — app, database, cache, message queue — is defined in a YAML file. Every developer on your team runs identical environments with one command. Why Use Docker for Development? Consistent environments — everyone runs the same versions of everything No installation required — no need to install PostgreSQL, Redis, or Node locally Easy onboarding — new team members run docker compose up and have everything Clean isolation — each project has its own versions, no conflicts between projects Production parity — dev environment matches production as closely as possible The Development Compose Pattern A common pattern is to have two Compose files: ...

A common mistake is shipping your entire build environment — compilers, package managers, SDKs — in your production Docker image. A Go application needs the Go compiler to build. But once it is built, the binary runs without Go installed at all. Why include 1 GB of Go tooling in an image that only needs a 10 MB binary? Multi-stage builds solve this. They let you compile your app in one container and copy only the final artifact into a minimal production image. ...

Containers are ephemeral. When a container stops, all data written inside it disappears. That is fine for stateless apps, but databases and file storage need to persist data. Docker solves this with volumes. And Docker solves container communication with networks. In this tutorial, you will learn both. The Ephemeral Container Problem When you run a PostgreSQL container and insert some rows, that data lives in the container’s writable layer. Stop the container, remove it, and start a new one — the data is gone. ...

Most real applications are not just one container. A typical web app has: A web server (nginx) An API server (your app) A database (PostgreSQL) A cache (Redis) Running four separate docker run commands, connecting them manually, and managing their configuration is painful. Docker Compose solves this. What is Docker Compose? Docker Compose lets you define your entire application stack in a single YAML file. Then you start everything with one command: ...

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. ...