fix: improve subpath handling in docker

[schembriaiden]

Pull Request Description

This pull request improves the Docker setup and entrypoint logic for the Fladder web application, focusing on better handling of custom web paths and permissions. The main changes involve normalizing and applying the FLADDER_WEBPATH variable more robustly, dynamically generating the Nginx configuration based on the deployment context, and ensuring correct file ownership for Nginx.

Entrypoint and Nginx configuration improvements:

• The docker-entrypoint.sh script now normalizes the FLADDER_WEBPATH variable, ensuring it always starts and ends with a single slash, and updates the <base href> in index.html accordingly.
• The script dynamically generates the Nginx configuration in /etc/nginx/conf.d/default.conf depending on whether Fladder is served at the root or a subpath, and selects the correct port based on the user (root or rootless).

File and directory permissions:

• Both Dockerfile and Dockerfile-rootless now ensure that /usr/share/nginx/html and /etc/nginx/conf.d are owned by the nginx user, preventing permission issues at runtime.
• Ownership of the docker-entrypoint.sh script is explicitly set to nginx:nginx in the rootless Dockerfile for consistency.

Issue Being Fixed

Resolves #917 (reply in thread)

Screenshots / Recordings

Tested On

• Android
• Android TV
• iOS
• Linux
• Windows
• macOS
• Web

Checklist

• If a new package was added, did you ensure it works for all supported platforms? Is the package well maintained
• Check that any changes are related to the issue at hand.

[Zepmann]

Consider an alternative: do not move files. Adjust the nginx configuration instead. That is more in line with other configuration files adjusted when starting a container.

[Zepmann]

@schembriaiden

Tested from my end. Looks good! Configured the environment variable:

FLADDER_WEBPATH=/fladder/

Without any workarounds from a reverse proxy running in front, Fladder is successfully served from https://example.com/fladder/ (also works without a backslash at the end).

[PartyDonut]

Looks good to me thanks for the quick implementation.

And thanks @Zepmann voor testing it out 👍🏼