This content originally appeared on DEV Community and was authored by Sarah Muriithi
GETTING STARTED WITH DOCKER AND DOCKER COMPOSE: A BEGINNER GUIDE
1. What is Docker?
- Docker is a tool used for building, running and managing containers.
- A Container is a lightweight, portable package that has everything an application needs to run-code, libraries, system tools and settings.
2. Install Docker
- On Ubuntu/Linux 
 - sudo apt install gnome-terminal
 - sudo apt update
 - sudo apt install -y docker.io
 - sudo systemctl enable -now docker
- On Windows/Mac 
 Install Docker Desktop
- After installation, run - docker versionto verify that docker is working.
3. Basic Docker Concepts
- Image
- It is a blueprint that contains everything needed to run an app.(OS libraries, dependencies and your code) 
- They are immutable. 
- Container
- It is a running instance of an image. 
- Containers are ephemeral -> you can start,stop, delete, and recreate them anytime. 
- Dockerfile
- It is a text file with instructions to build a custom image. 
- An example: 
 - FROM python:3.12
 WORKDIR /app
 COPY requirements.txt .
 RUN pip install -r requirements.txt
 COPY . .
 CMD ["python", "app.py"]
- Docker Hub/Registry
- A registry is where images are stored. 
- Docker hub is the default public registry and one can also have private registries. 
- Docker Engine
- The underlying runtime that builds and runs containers.
- Includes: 
- Deamon(dockerd) -> background services. 
- CLI(docker) -> command-line tool. 
- API -> programmatic access. 
4. Basic Docker Commands
- List images
docker images
- List running containers
docker ps
- Run a container
docker run -d -p 8080:80 nginx
- Then visit http://localhost:8080 in your browser
- Stop a container
docker stop <container id>
5. What is Docker Compose
- Docker Compose lets you define and run multi-container applications.
- Instead of starting containers one by one, you define everything in a docker-compose.yml file and run:
docker compose up
6. Install Docker Compose
- If you installed Docker Desktop, Compose is already included.
- On Linux:
sudo apt install docker-compose-plugindocker compose version
7. Useful Docker compose Commands
- Start containers: 
 - docker compose up -d
- Stop containers: 
 - docker compose down
- View logs: 
 - docker compose logs -f
- Restart a service: 
 - docker compose restart web
This content originally appeared on DEV Community and was authored by Sarah Muriithi
 
	
			Sarah Muriithi | Sciencx (2025-08-27T05:09:13+00:00) DOCKER. Retrieved from https://www.scien.cx/2025/08/27/docker-3/
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