Understanding Docker in 10 Minutes

Docker is the reason self-hosting went from “sysadmin hobby” to “anyone can do it.” It packages software into neat, isolated containers that run the same everywhere.

You don’t need to become a Docker expert. You need to understand four concepts.

Concept 1: Images

An image is a snapshot of software — pre-built, pre-configured, ready to run. Think of it like an .iso file, but for apps.

# Download the Plausible Analytics image
docker pull plausible/analytics:latest

Images live on Docker Hub  — a public registry of 100,000+ images. When our deploy guides say image: plausible/analytics:latest, they’re pulling from here.

Concept 2: Containers

A container is a running instance of an image. Image = blueprint. Container = the actual building.

# Start a container from an image
docker run -d --name my-plausible plausible/analytics:latest
 
# See running containers
docker ps
 
# Stop a container
docker stop my-plausible
 
# Remove a container (data in volumes is safe)
docker rm my-plausible

💡 Why? Containers are isolated from each other and from your host system. Breaking one container doesn’t break anything else.

Concept 3: Volumes

Volumes store your data outside the container. This is critical because containers are disposable — when you update an image, you destroy the old container and create a new one. Volumes survive this process.

# Mount a volume called "plausible-data"
docker run -v plausible-data:/var/lib/clickhouse plausible/analytics

Without volumes, your data dies when the container dies. Always use volumes.

# List all volumes
docker volume ls
 
# Backup a volume (copy to local tar)
docker run --rm -v plausible-data:/data -v $(pwd):/backup alpine \
  tar czf /backup/plausible-backup.tar.gz /data

Concept 4: Docker Compose

This is the big one. Docker Compose lets you define multi-container setups in a single YAML file. Most real-world tools need multiple containers (app + database + cache), and Docker Compose handles that.

# docker-compose.yml
version: '3.8'
 
services:
  app:
    image: plausible/analytics:latest
    ports:
      - "8000:8000"
    depends_on:
      - db
 
  db:
    image: postgres:14-alpine
    volumes:
      - db_data:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: supersecret
 
volumes:
  db_data:

Then run it:

# Start everything
docker compose up -d
 
# See logs
docker compose logs -f
 
# Stop everything
docker compose down
 
# Update to latest images
docker compose pull && docker compose up -d

That’s the pattern for every single deploy guide in these docs:

1. Copy the docker-compose.yml
2. Tweak the environment variables
3. Run docker compose up -d
4. Done.

The 5 Commands You’ll Actually Use

That’s it. That’s Docker for self-hosters.

Next Steps

→ Reverse Proxies Explained — How to access your tools via app.yourdomain.com → Your First Deployment — Put this knowledge to use