Docker Tutorial — Introduction to Docker
This chapter introduces what containers are, how Docker works, and why containers changed the way we build and ship software.
What’s in this Chapter?
| # | Topic | Permalink |
|---|---|---|
| 1 | What Are Containers? | The problem containers solve, process isolation |
| 2 | Docker vs Virtual Machines | Hypervisors vs container runtimes, when to use each |
| 3 | Why Docker? | Reproducibility, speed, density, microservices |
| 4 | Docker Ecosystem Overview | Engine, CLI, Desktop, Hub, Compose, BuildKit |
| 5 | OCI Standards | Image Spec, Runtime Spec, portability |
| 6 | Practice Exercises | Hands-on labs and questions |
Chapter Overview
Before Docker existed, deploying software was painful. Developers would build an app on their laptop, hand it off to ops, and then spend hours debugging why it didn’t work in staging. The infamous “works on my machine” was the most common excuse in software engineering.
Containers solved this by packaging your code and its entire environment into a single, portable unit. Docker made containers simple enough for anyone to use.
This chapter answers fundamental questions:
- What is a container, and how is it different from a virtual machine?
- Why did Docker become the industry standard for containers?
- What components make up the Docker ecosystem?
- What are OCI standards and why do they matter?
Key Concepts Preview
| Term | Definition |
|---|---|
| Container | A lightweight, isolated environment that packages code + dependencies |
| Image | A read-only template used to create containers |
| Docker Engine | The core runtime that builds and runs containers |
| Docker Hub | The public registry for sharing container images |
| OCI | Open Container Initiative — industry standards for containers |
| Namespace | Linux kernel feature that isolates container processes |
| cgroup | Linux kernel feature that limits container resources |
What You’ll Be Able to Do After This Chapter
- Explain what a container is and how it differs from a VM
- Describe why Docker became the standard for containerization
- List the key components of the Docker ecosystem
- Understand the OCI standards that make containers portable
- Articulate the business and technical benefits of containers
