Preguntes Freqüents - FAQ

With Docker installed, this hands-on walkthrough covers the core workflow you'll use constantly: pulling images, running containers, checking logs, and managing their lifecycle — using a real Nginx web server as the example.

Prerequisites

• Docker Engine installed and running
• Root or sudo access, or your user added to the docker group

Step 1 — Pull an Image

docker pull nginx:latest

List downloaded images:

docker images

Step 2 — Run Your First Container

docker run -d \
  --name webserver \
  -p 80:80 \
  --restart unless-stopped \
  nginx:latest

-d runs it in the background, --name gives it a memorable name, -p 80:80 maps the host's port 80 to the container's port 80, and --restart unless-stopped ensures it survives reboots.

Step 3 — Verify It's Running

docker ps

Visit http://YOUR_SERVER_IP in a browser to see the default Nginx page.

Step 4 — View Container Logs

docker logs webserver

Follow logs live:

docker logs -f webserver

Step 5 — Open a Shell Inside the Container

docker exec -it webserver bash

exit

Step 6 — Stop, Start, and Restart

docker stop webserver
docker start webserver
docker restart webserver

Step 7 — Serve Your Own Files

Mount a local directory into the container instead of the built-in default page:

mkdir ~/website
echo "<h1>Hello from my VPS</h1>" > ~/website/index.html

docker run -d \
  --name mysite \
  -p 80:80 \
  -v ~/website:/usr/share/nginx/html:ro \
  nginx:latest

Step 8 — Remove a Container

docker stop webserver
docker rm webserver

Common Errors

"Port is already allocated" — another process or container is using port 80:

sudo ss -tulpn | grep :80

Use a different host port instead, e.g. -p 8080:80.

Container exits immediately — check the logs for the actual error:

docker logs webserver

Best Practices

• Always name your containers with --name for easier management
• Use volumes for anything that needs to persist beyond the container's lifecycle
• Prefer official images from Docker Hub over unverified third-party sources

FAQ

What happens to data if I delete a container?
Any data not stored in a mounted volume is lost — see Docker Volumes: Persisting Data for how to avoid this.

Related Articles

• How to Install Docker Engine on Ubuntu & Debian
• Docker Volumes: Persisting Data
• Docker Networking Explained