---
title: Docker
description: "Containers for running applications in a consistent environment. Image, container, volume, and network are the core terms."
canonical: https://penasihathosting.com/en/hosting-wiki/docker
type: wiki
locale: en
updated: 2026-10-29
author: Willya Randika
---

# Docker

## Overview

- **Summary:** Containers for running applications in a consistent environment. Image, container, volume, and network are the core terms.
- **Author:** Willya Randika ([profile](/penulis/willya-randika))

## Article

**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

| Term | Meaning |
| --- | --- |
| **Image** | Read-only template with the application and dependencies |
| **Container** | A running instance of an image |
| **Volume** | Persistent storage outside the container lifecycle |
| **Network** | Virtual network between containers |
| **Dockerfile** | Recipe for building an image |
| **Compose** | Definition of several containers in one file |

## Basic flow

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

For data that must survive, mount a volume:

```bash
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

<Accordion>
  <AccordionItem title="Can Docker replace a VPS?">
    No. Docker packages and runs applications; the VPS is the machine the containers run on.
  </AccordionItem>
  <AccordionItem title="Does data disappear when a container restarts?">
    Data in the container filesystem can disappear when the container is removed. Use a volume for data that must persist.
  </AccordionItem>
  <AccordionItem title="Is Docker safe for production?">
    It can be, provided images are updated, containers do not run as root, resources are limited, and network access is controlled.
  </AccordionItem>
</Accordion>