Case study

Case Study: Docker Compose stack failing after migration planning due to volume permissions

This example shows how a production infrastructure problem can be investigated methodically, improved safely and turned into clearer operational practice.

Context

A small SaaS or web application had been moved from one Linux host to another using Docker Compose.

The Compose file, images and database settings were largely intact, but the restored application data did not behave the same way on the new server.

The problem

  • Containers started, then failed or restarted when the application tried to write cache, session, upload or runtime files.
  • The restored volume data had been copied as root:root instead of the UID/GID expected by the application container.
  • The issue looked like an application or Compose failure, but the real fault was host-side ownership on mounted data.
  • Permissions needed to be corrected carefully because the same volumes contained live application and database-related data.

Our approach

  • Reviewed Docker compose configuration, container logs, bind mounts and named volumes to identify which path was failing.
  • Checked the user and group used inside the container, then compared that with host-side ownership on the restored data.
  • Corrected ownership only on the affected mounted paths, then restarted the stack and confirmed the app could write normally.
  • Documented the expected UID/GID mapping and restore steps so future migration projects preserve permissions properly.

Hands-on outcomes

Stack stabilisedThe containers stopped restarting once the application could write to its restored data directories.
Root cause confirmedThe issue was narrowed to volume ownership rather than blindly rebuilding images or changing application settings.
Data handled safelyPermission changes were applied to the right paths after checking mounts, users and ownership first.
Migration Planning process improvedThe customer received clearer restore notes covering UID/GID preservation, volume checks and post-migration planning testing.

Relevant technologies and keywords

These are the main technologies, solutions and search terms connected to this case study.

Docker ComposeLinux migration planningVolume permissionsBind mountsUID and GIDContainer restartFile ownershipApplication uploadsCache directoryDatabase volume

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