Volumes

Docker · Reference cheat sheet

📋 Overview

Volumes persist data beyond a container’s lifecycle and share files between host and container. Prefer named volumes for databases; bind mounts for live code in development.

🔧 Core concepts

💡 Examples

Named volume for Postgres:

docker volume create pgdata
docker run -v pgdata:/var/lib/postgresql/data postgres:16

Compose volume:

services:
  db:
    image: postgres:16-alpine
    volumes:
      - pgdata:/var/lib/postgresql/data
volumes:
  pgdata:

Dev bind mount:

docker run --rm -v "${PWD}:/app" -w /app node:22 npm test

⚠️ Pitfalls

• Bind-mounting over a path that had image data hides the image content.
• Permissions (UID/GID) on Linux bind mounts often break writes — match users.
• docker compose down -v deletes named volumes — destructive.

🔗 Related

• compose.md
• getting_started.md
• env_secrets.md
• networks.md