Docs: Fix PostgreSQL volume mapping to prevent data loss

[fankes]

After testing, I found a critical error in the configuration documentation regarding the PostgreSQL database volume mapping. The current configuration prevents data from persisting correctly during container restarts or migrations, leading to data loss. Below are the details of the fix.

The Issue

The current docker-compose.yml example for PostgreSQL uses ./postgresql:/var/lib/postgresql as a volume mapping.

According to the official PostgreSQL Docker image documentation, the data directory is located at /var/lib/postgresql/data. Mapping the parent directory instead of the specific data subdirectory is a "hidden trap" that leads to:

1. Data Persistence Failures: The database may fail to re-attach to existing data after a container recreation.
2. Permission Conflicts: Mapping the parent directory often causes permission issues on the host side, leading to initialization loops (as I experienced multiple times).

The Fix

Updated the documentation example to explicitly point to the /data subdirectory:
./postgres_data:/var/lib/postgresql/data.

This ensures that the internal database files are correctly persisted for users following this guide.

[nginxproxymanagerci]

Docker Image for build 1 is available on DockerHub:

nginxproxymanager/nginx-proxy-manager-dev:pr-5417

Note

Ensure you backup your NPM instance before testing this image! Especially if there are database changes.
This is a different docker image namespace than the official image.

Warning

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