Docker vs Docker Compose

A common question for beginners is: "What is the difference between Docker and Docker Compose?"

The Short Answer

Docker (specifically the docker CLI) is used to manage individual containers.
Docker Compose is used to manage multi-container applications.

Feature	Docker CLI (`docker run`)	Docker Compose (`docker compose up`)
Scope	Single Container	Multi-Container Application
Configuration	Command line flags	YAML file (`docker-compose.yml`)
Networking	Manual (`--network`)	Automatic (creates a default network)
Volumes	Manual (`-v`)	Defined in YAML, easy to reuse
Reproducibility	Low (long commands)	High (config as code)
Use Case	Quick tests, one-off scripts	Development environments, production stacks

Use docker run when you just need to spin up a single tool quickly.

Example: Running a quick Python script.

docker run -it --rm python:3.9 python -c "print('Hello World')"

Use Docker Compose for anything that involves more than one container, or even a single container if you want to save the configuration.

Example: Running a web server that needs a database.

docker-compose.yml:

services:
  web:
    image: my-web-app
    ports: ["80:80"]
  db:
    image: postgres
    environment:
      POSTGRES_PASSWORD: secret

Command:

docker compose up -d

Another common confusion is between Dockerfile and docker-compose.yml.

Dockerfile: A recipe for building a Docker image. It tells Docker how to create the image (install apt packages, copy code, set env vars).
docker-compose.yml: A recipe for running containers. It tells Docker how to run images (which ports to open, which volumes to mount, which networks to join).

You often use them together: Compose reads your Dockerfile to build the image, then runs it.

Whether you have a single Docker image or a complex Compose stack, Hostim.dev runs it on bare metal with zero config.