Cheat SheetsDockerStorage

Storage — Cheat Sheet

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Cheat Sheet · AiCanCode.org
Storage
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Docker Volumes & Persistence

Container filesystems are ephemeral — data is lost when a container is removed. Docker volumes and bind mounts persist data outside the container lifecycle.

  • ✓Container writable layers are ephemeral — data is lost when the container is removed.
  • ✓Named volumes are Docker-managed and persist across container restarts and deletions.
  • ✓Bind mounts expose host directories into the container — ideal for development.
  • ✓tmpfs mounts store data in memory only — useful for secrets and temp files.
  • ✓Back up volumes by running a temporary Alpine container that tars the mounted volume.
  • ✓Database containers (Postgres, MySQL, Redis) always need a named volume in production.
bash — named volume vs bind mount
# ── Named Volume ───────────────────────────────────────

# Create a volume

docker volume create postgres-data



# Use it (postgres writes to /var/lib/postgresql/data → saved in volume)

docker run -d \

  --name postgres \

  -v postgres-data:/var/lib/postgresql/data \   # named volume mount

  -e POSTGRES_PASSWORD=secret \

  postgres:16



# Data persists across container removal/recreation:

docker rm -f postgres

docker run -d --name postgres -v postgres-data:/var/lib/postgresql/data postgres:16

# ↑ same data — the volume still has it



# ── Bind Mount ─────────────────────────────────────────

# Mount current directory into container (hot-reload for dev)

docker run -d \

  --name dev-server \

  -v $(pwd)/src:/app/src \    # host path:container path

  -p 3000:3000 \

  my-app:dev

# Edit src/ on host → changes immediately visible inside container
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