Chapter 2 — Install Docker + Your First Container

Course: Docker (Zero to Hero) · Chapter: 2 of 8 Read on the website: learn.bazardev.com/docker/02-install-and-first-container

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Time to get hands-on. By the end of this chapter you will have Docker installed, you'll have run two containers, and you'll understand exactly what each command did.

1. Installing Docker

Linux (Ubuntu/Debian — the official convenience script)

curl -fsSL https://get.docker.com -o get-docker.sh
sudo sh get-docker.sh

Then let your user run docker without typing sudo every time:

sudo usermod -aG docker $USER

Log out and log back in (or reboot) for the group change to take effect.

macOS / Windows

Install Docker Desktop — it bundles the Docker Engine, CLI, and a GUI, inside a lightweight VM:

macOS: docker.com/products/docker-desktop
Windows: same link, requires WSL2 enabled.

Verify the install

docker --version
docker info

If docker info prints a big block of server details without errors, the Docker daemon is running correctly.

2. Your first container: `hello-world`

docker run hello-world

You'll see output like:

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
...
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Here's exactly what happened, step by step — this is the Chapter 1 architecture diagram, now actually running:

The CLI sent docker run hello-world to the Daemon.
The Daemon looked for a hello-world image locally — didn't find one.
It pulled the image from Docker Hub.
It started a container from that image.
The container printed its message and exited (its one job was done).

Run docker run hello-world again — notice it's instant this time, because the image is now cached locally. No download needed.

3. A real container: nginx (a web server)

docker run -d -p 8080:80 --name my-nginx nginx

Now open http://localhost:8080 (or http://<your-server-ip>:8080) in a browser — you'll see the nginx welcome page, served from inside a container.

Breaking down the flags:

Flag	Meaning
`-d`	Detached — run in the background, give you back your terminal
`-p 8080:80`	Port mapping — `host_port:container_port`. Requests to port 8080 on your machine get forwarded to port 80 inside the container (where nginx listens)
`--name my-nginx`	Give the container a friendly name, instead of a random one Docker would generate
`nginx`	The image to run (pulled from Docker Hub automatically, since you don't have it yet)

4. Looking at running containers

docker ps

Shows all running containers — you should see my-nginx with status Up.

docker ps -a

Shows all containers, including stopped ones (like the hello-world container, which exited right after printing its message).

docker logs my-nginx

Shows the output/logs of that container — useful for debugging when something's not working as expected.

5. Stopping and removing a container

docker stop my-nginx
docker rm my-nginx

stop gracefully shuts the container down (it still exists, just not running).
rm removes it completely.

You can also do both in one shot:

docker rm -f my-nginx

6. A quick look at images

docker images

Lists every image you've pulled or built, locally. You'll see hello-world and nginx in that list now. We'll go deep on images vs. containers — and the commands around them — in Chapter 3.

7. Key takeaways

docker run <image> pulls the image (if needed) and starts a container from it.
-d runs in the background; -p host:container maps ports so you can reach the container from outside.
docker ps shows running containers; docker ps -a shows all of them, running or stopped.
docker stop pauses a container; docker rm deletes it; docker rm -f does both.
docker images lists what you have stored locally.

8. Test yourself (exam prep)

Q1. What's the difference between `docker ps` and `docker ps -a`?

docker ps shows only currently running containers. docker ps -a shows every container, including ones that have stopped or exited.

Q2. In `docker run -d -p 8080:80 nginx`, what does `8080:80` mean?

It maps port 8080 on your host machine to port 80 inside the container. Traffic hitting localhost:8080 gets forwarded to port 80, where nginx is listening inside the container.

Q3. Why was the second `docker run hello-world` instant, while the first one took a few seconds?

The first run had to pull the hello-world image from Docker Hub over the network. The second run found the image already cached locally, so no download was needed — it just started a new container from the cached image immediately.

Q4. What's the difference between `docker stop` and `docker rm`?

docker stop shuts the container down but keeps it around (you could docker start it again later). docker rm deletes the container entirely. docker rm -f stops and removes it in one step.

9. Free resources

Official docs: Install Docker Engine
Official docs: Docker run reference
YouTube: "Docker Tutorial for Beginners [FULL COURSE in 3 Hours]" — channel: TechWorld with Nana (covers this exact install + first-run flow)

Next: Chapter 3 — Images vs Containers → (coming soon)