Docker crash course

Introduction

• What containers are and why they matter
• Containers vs Virtual Machines
• Docker overview: engine, CLI, registry

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1. Core Docker concepts

1.1 Architecture & terminology

• Docker daemon, client, images, containers, registries
• Layers & the UnionFS concept

1.2 Basic commands

• docker pull, run, ps, stop, rm, rmi
• Detached mode, ports (-p), environment vars (-e), volumes (-v)
• Inspecting containers: docker logs, exec, inspect

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2. Building and managing images

2.1 Dockerfile essentials

• Key instructions: FROM, RUN, COPY, WORKDIR, CMD, EXPOSE, ENV
• Build images (docker build), tagging, caching
• Lightweight and secure image best practices

2.2 Registries & sharing

• Docker Hub and private registries
• docker push, docker login, image tags and versioning

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3. Data & networking

3.1 Volumes and persistence

• Bind mounts vs named volumes
• Typical use case: persisting database data

3.2 Networking basics

• Default bridge network
• Custom networks (docker network create, connect)
• Exposing services, container-to-container communication

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4. Multi-container apps

• Intro to Docker Compose
• Structure of a docker-compose.yml
• docker compose up/down, scaling services, environment variables

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5. Podman in a nutshell

5.1 What Podman is

• Daemonless and rootless approach
• CLI compatibility: alias docker=podman

5.2 Key differences & when to use

• Rootless containers for better isolation
• Pod concept (groups of containers)
• Integration with systemd
• Compatibility notes and ecosystem tradeoffs