Docker Compose — Volume Lifecycle

Understanding when volumes are created, preserved, and removed is critical for data safety. This page covers the complete volume lifecycle.

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Volume Lifecycle Diagram

docker compose up        docker compose down       docker compose down -v
      │                        │                          │
      ▼                        ▼                          ▼
┌─────────────┐          ┌─────────────┐          ┌─────────────┐
│ Volume      │          │ Volume      │          │ Volume      │
│ CREATED     │          │ KEPT ✅     │          │ REMOVED ❌  │
│ (if not     │          │ (data safe) │          │ (data lost) │
│  existing)  │          │             │          │             │
└─────────────┘          └─────────────┘          └─────────────┘

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Creating Volumes

Volumes are created automatically when you run docker compose up:

docker compose up -d

[+] Running 3/3
 ✔ Network myapp_default  Created
 ✔ Volume myapp_pgdata    Created      ← Volume created
 ✔ Container myapp-db-1   Started

If the volume already exists, Compose reuses it — no data is lost.

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Listing Volumes

# List all Docker volumes
docker volume ls

DRIVER    VOLUME NAME
local     myapp_pgdata
local     myapp_redis-data

# Filter by project
docker volume ls --filter label=com.docker.compose.project=myapp

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Inspecting Volumes

docker volume inspect myapp_pgdata

[
    {
        "CreatedAt": "2025-01-01T00:00:00Z",
        "Driver": "local",
        "Mountpoint": "/var/lib/docker/volumes/myapp_pgdata/_data",
        "Name": "myapp_pgdata",
        "Scope": "local"
    }
]

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Removing Volumes

With docker compose down -v

# ⚠️ This removes ALL named volumes defined in the compose file
docker compose down -v

[+] Running 3/3
 ✔ Container myapp-db-1   Removed
 ✔ Volume myapp_pgdata    Removed      ← Volume removed!
 ✔ Network myapp_default  Removed

Manual Removal

# Remove a specific volume
docker volume rm myapp_pgdata

# Remove all unused volumes (⚠️ dangerous)
docker volume prune

Volume Removal Rules

Action	Named Volumes	Anonymous Volumes
docker compose down	Kept ✅	Removed
docker compose down -v	Removed ❌	Removed
docker compose rm	Kept ✅	Removed
docker volume prune	Removed if unused ❌	Removed ❌

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Backing Up Volume Data

Since volumes are Docker-managed, you need a container to access the data:

# Backup a volume to a tar file
docker run --rm \
  -v myapp_pgdata:/data \
  -v $(pwd):/backup \
  alpine tar czf /backup/pgdata-backup.tar.gz -C /data .

# Restore from backup
docker run --rm \
  -v myapp_pgdata:/data \
  -v $(pwd):/backup \
  alpine sh -c "cd /data && tar xzf /backup/pgdata-backup.tar.gz"

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Summary

Operation	Volumes
docker compose up	Created (if new)
docker compose down	Kept (safe)
docker compose down -v	Removed (data lost!)
docker volume prune	Removes unused volumes
Backup	Use a helper container with tar

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Quick Reference

Item	Detail
Create	Automatic on docker compose up
Preserve	docker compose down keeps volumes
Remove	docker compose down -v removes volumes
List	docker volume ls
Inspect	docker volume inspect
Backup	Use alpine container with tar