Docker-Tutorial

This is the complete Docker reference for 2026. All essential commands in one place. Versions covered: Docker Engine 29+, Docker Compose v2 (Compose Specification v5). Container Commands # Run a container docker run nginx # Run in detached mode (background) docker run -d nginx # Run interactively with a shell docker run -it ubuntu:24.04 bash # Run and remove when stopped docker run --rm nginx # Run with a name docker run --name mywebserver nginx # Run with port mapping (host:container) docker run -p 8080:80 nginx # Run with environment variables docker run -e APP_ENV=production myapp:1.0 # Run with environment file docker run --env-file .env myapp:1.0 # Run with volume docker run -v mydata:/data nginx # Run with bind mount docker run -v /host/path:/container/path nginx # Run with resource limits docker run --memory 512m --cpus 1.0 myapp:1.0 # Run as non-root user docker run --user 1001:1001 myapp:1.0 # Run with read-only filesystem docker run --read-only myapp:1.0 # Run with network docker run --network mynetwork myapp:1.0 # Run with restart policy docker run --restart unless-stopped nginx # List running containers docker ps # List all containers (including stopped) docker ps -a # Stop a container (SIGTERM) docker stop mywebserver # Kill a container (SIGKILL) docker kill mywebserver # Start a stopped container docker start mywebserver # Restart a container docker restart mywebserver # Remove a stopped container docker rm mywebserver # Force-remove a running container docker rm -f mywebserver # Remove all stopped containers docker container prune # View container logs docker logs mywebserver # Follow logs in real time docker logs -f mywebserver # Show last 50 lines docker logs --tail 50 mywebserver # Execute a command in a running container docker exec -it mywebserver bash # Copy files to/from a container docker cp mywebserver:/etc/nginx/nginx.conf ./nginx.conf docker cp ./nginx.conf mywebserver:/etc/nginx/nginx.conf # Inspect container details (JSON) docker inspect mywebserver # View real-time resource usage docker stats # View stats for one container docker stats mywebserver # View running processes inside a container docker top mywebserver Image Commands # Pull an image from Docker Hub docker pull nginx # Pull specific version docker pull nginx:1.27 # List local images docker images # Build an image from Dockerfile docker build -t myapp:1.0 . # Build from specific Dockerfile docker build -f Dockerfile.prod -t myapp:prod . # Build with build args docker build --build-arg APP_VERSION=2.0 -t myapp:2.0 . # Tag an image docker tag myapp:1.0 myapp:latest docker tag myapp:1.0 kemalcodes/myapp:1.0 # Push to Docker Hub docker push kemalcodes/myapp:1.0 # Remove an image docker rmi nginx # Remove all unused images docker image prune # Remove all unused images (including tagged but not referenced) docker image prune -a # View image history (layers) docker history nginx # Inspect image details (JSON) docker inspect nginx # Save image to tar file docker save myapp:1.0 -o myapp.tar # Load image from tar file docker load -i myapp.tar Volume Commands # Create a named volume docker volume create mydata # List all volumes docker volume ls # Inspect a volume docker volume inspect mydata # Remove a volume docker volume rm mydata # Remove all unused volumes docker volume prune Network Commands # List all networks docker network ls # Create a network docker network create mynetwork # Create with specific driver docker network create --driver bridge mynetwork # Inspect a network docker network inspect mynetwork # Connect a container to a network docker network connect mynetwork mycontainer # Disconnect a container from a network docker network disconnect mynetwork mycontainer # Remove a network docker network rm mynetwork # Remove all unused networks docker network prune Docker Compose Commands Always use docker compose (v2 plugin), not docker-compose (v1, deprecated). ...

Most beginner Docker setups have serious security problems. Containers running as root. Passwords in Dockerfiles. Outdated base images with known vulnerabilities. No resource limits. This tutorial covers the most important Docker security practices. You do not need to implement all of them at once. Start with the first three — they will fix the most critical issues. 1. Never Run Containers as Root By default, processes inside Docker containers run as root (UID 0). If an attacker exploits a vulnerability in your app, they have root access inside the container — and potentially a path to the host. ...

“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. ...