Docker

Docker is a container platform that packages an application and its dependencies into an image, then runs it as an isolated container. In hosting, Docker is used for applications, databases, queues, or internal tools that need a consistent environment.

Core terms

Basic flow

docker build -t my-app .
docker run -d --name app -p 3000:3000 my-app

For data that must survive, mount a volume:

docker run -d -v app-data:/var/lib/app my-app

What to watch for

• A container is not a VM. Isolation is lighter; do not treat it as a full security boundary.
• Data belongs in a volume. Files inside the container disappear when it is removed.
• Resource limits matter. Without CPU/RAM limits, one container can exhaust the VPS.
• Update images regularly. Old images carry unpatched vulnerabilities.
• RAM and disk are finite. A small VPS with many containers runs out quickly.
• Ports and reverse proxy. Containers usually listen on an internal port, then Nginx/Caddy forwards HTTPS traffic.

Every container uses RAM and disk. On a 1–2 GB VPS, run only the services you need, set memory limits, and monitor image size. Use docker system prune regularly, but never remove volumes still in use. For production, store images in a registry and deploy explicit versions, not latest. Separate the database from the app container when possible.

FAQ