Gotcha: Docker volumes persist data even after container removal

Old Docker volumes accumulate and consume disk space. Developers assume data is cleaned up when containers are removed.

Docker volumes persist independently of containers:

# List volumes:
docker volume ls

# See which volumes are dangling (not attached to any container):
docker volume ls -f dangling=true

# Remove specific volume:
docker volume rm <volume_name>

# Remove ALL unused volumes:
docker volume prune

# Remove container AND its anonymous volumes:
docker rm -v <container_id>

# docker-compose down does NOT remove volumes:
docker compose down # Keeps volumes
docker compose down -v # Removes named volumes too
docker compose down --volumes --rmi all # Nuclear cleanup

# Check disk usage:
docker system df # Overview of disk usage
docker system df -v # Detailed breakdown

# Full cleanup (containers, images, networks, volumes):
docker system prune -a --volumes

Common surprise: database data from dev docker-compose persists
across project rebuilds unless you explicitly remove the volume.