Why Docker Exists
Developers were tired of hearing "it works on my machine."
Works here
Fails there
Fails there
Primer / Resources / About
Learn containers before setup problems waste the day.
Docker runs applications inside containers so the required files, tools, libraries, and settings travel together.
Primer
1. Run a container
Start a temporary container from an existing image.
docker run hello-world
2. See running containers
List the containers currently running on the machine.
docker ps
3. Use Compose
Start a multi-container project from a Compose file.
docker compose up
Resources
Web Apps
Docker can package websites, APIs, and backend services.
Databases
Developers often run MySQL, PostgreSQL, Redis, and other services in containers.
DevOps
Docker is commonly used in build, test, and deployment workflows.
Local Testing
Containers help test without changing the whole computer.
Cloud Deployment
Cloud platforms often deploy applications from container images.
Team Projects
Docker helps teams run matching environments.
About
Containers
Running application environments created from images.
Images
Reusable packages that contain the application and its requirements.
Dockerfiles
Instructions for building your own container image.
Compose
A way to run multiple related containers together.
Lecture + worksheet
Job-ready Docker practice cards
Docker changed how software is delivered. Learn why containers exist, what problems they solve, what breaks, and how professionals use them safely.
The Shipping Container Idea
Docker succeeded because software began travelling inside standardized containers.
Build Once → Run Anywhere
Applications Need Dependencies
Programs often depend on libraries, versions, and tools that may differ between systems.
App + Dependencies
Containers Are Not Virtual Machines
Containers and virtual machines solve different problems.
Container ≠ VM
Images Create Containers
Images are templates. Containers are running instances.
Image → Container
Data Must Survive Restarts
Containers come and go. Important data must survive.
Container dies
Data lives
Data lives
Containers Need Networks
Applications rarely work alone. Containers need communication.
Web → API → Database
Logs Are Evidence
When containers fail, logs usually explain what happened.
Evidence Beats Guessing
Production Is Different
Real traffic, updates, storage, security, and monitoring create new challenges.
Works Locally ≠ Production Ready
Docker Is A Tool Not A Goal
The goal is delivering reliable software. Docker is one tool that helps.
Problem → Solution → Result