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NetAlertX/docs/FILE_PERMISSIONS.md
jokob-sk 61de63771b DOCS: Docker guides
Signed-off-by: jokob-sk <jokob.sk@gmail.com>
2025-10-29 15:51:31 +11:00

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# Managing File Permissions for NetAlertX on Nginx with Docker
> [!TIP]
> If you are facing permission issues, try to start the container without mapping your volumes. If that works, then the issue is permission related. You can try e.g., the following command:
> ```
> docker run -d --rm --network=host \
> -e TZ=Europe/Berlin \
> -e PUID=200 -e PGID=200 \
> -e PORT=20211 \
> ghcr.io/jokob-sk/netalertx:latest
> ```
NetAlertX runs on an Nginx web server. On Alpine Linux, Nginx operates as the `nginx` user (if PUID and GID environment variables are not specified, nginx user UID will be set to 102, and its supplementary group `www-data` ID to 82). Consequently, files accessed or written by the NetAlertX application are owned by `nginx:www-data`.
Upon starting, NetAlertX changes nginx user UID and www-data GID to specified values (or defaults), and the ownership of files on the host system mapped to `/app/config` and `/app/db` in the container to `nginx:www-data`. This ensures that Nginx can access and write to these files. Since the user in the Docker container is mapped to a user on the host system by ID:GID, the files in `/app/config` and `/app/db` on the host system are owned by a user with the same ID and GID (defaults are ID 102 and GID 82). On different systems, this ID:GID may belong to different users, or there may not be a group with ID 82 at all.
Option to set specific user UID and GID can be useful for host system users needing to access these files (e.g., backup scripts).
### Permissions Table for Individual Folders
| Folder | User | User ID | Group | Group ID | Permissions | Notes |
|----------------|--------|---------|-----------|----------|-------------|---------------------------------------------------------------------|
| `/app/config` | nginx | PUID (default 102) | www-data | PGID (default 82) | rwxr-xr-x | Ensure `nginx` can read/write; other users can read if in `www-data` |
| `/app/db` | nginx | PUID (default 102) | www-data | PGID (default 82) | rwxr-xr-x | Same as above |
### Fixing Permission Problems
The container fails to start with "Permission Denied" errors. This typically happens when your data volumes (`netalertx_config`, `netalertx_db`) are "owned" by the `root` user (UID 0) from a previous install, but the secure container must run as the `netalertx` user (UID 20211).
### Solution
1. Run the container **once** as the `root` user (`--user "0"`) to trigger the built-in fix-it mode:
```bash
docker run -it --rm --name netalertx-fix --user "0" \
-v netalertx_config:/app/config \
-v netalertx_db:/app/db \
netalertx:latest
```
2. Wait for the logs to show a **magenta warning** and confirm permissions are being fixed. The container will then hang (this is intentional).
3. Press **Ctrl+C** to stop the fix-it container.
4. Start your container normally (e.g., with `docker-compose up -d` or your standard `docker run` command).
### About This Method
The containers startup script detects it is running as `root` (UID 0). It automatically runs the `chown` command to fix the permissions on your volume files, setting them to the correct `20211` user. It then hangs (`sleep infinity`) to prevent you from *ever* running the application as `root`, forcing you to restart securely.