Docker volumes: keep app data outside disposable containers
Understand named volumes, database paths and the difference between restarting a service and protecting data.
App Cities · 2 min · Updated
Docker can replace a container when you deploy a new version. Files kept only inside that container may be lost. A named volume keeps data outside that replaceable part. Use it for things like database files and uploads. A volume is still live storage. It is not a backup.
The steps
- Identify every path that contains changing data: database files, user uploads and generated assets. Do not confuse these with source code or dependency caches.
- Declare named volumes in Compose and mount them at the paths expected by the service images. Check the image documentation rather than guessing.
- Write a test record or upload, restart the service through the supported controls and verify the data is still present.
- Enable and test the appropriate backup option for important data. Keep a recovery copy independent of the running application when your needs require it.
A common question
Is a volume automatically a backup?
No. It is active storage. A backup is a separate recoverable copy with a known restore procedure.
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