Feat/keep permissions

[mpalermo73]

---

• I have read the contributing guideline and understand that I have made the correct modifications

---

Description:

Adds a KEEP_PERMISSIONS environment variable that, when set to true, skips the forced chmod operations the container applies to /config, /run/ddclient-cache, and /config/ddclient.conf on startup and on every inotify-triggered config reload.

Changed files:

• root/etc/s6-overlay/s6-rc.d/init-ddclient-config/run — skip chmod 700 on /config and /run/ddclient-cache, and chmod 600 on /config/*, when KEEP_PERMISSIONS=true
• root/etc/s6-overlay/s6-rc.d/svc-inotify/run — skip chmod 600 on /config/ddclient.conf after inotify-detected changes when KEEP_PERMISSIONS=true; the env var is cached before the inotify loop to avoid re-evaluating it on every file-change event

Default behaviour (KEEP_PERMISSIONS unset or any value other than true) is unchanged.

Benefits of this PR and context:

Users running with NFS-mounted /config volumes, custom ACLs, rootless runtimes, or any setup where they own and manage file permissions find that the container silently resets their permissions to 700/600 on every restart and every time ddclient.conf is touched. There is currently no escape hatch short of patching the s6 scripts themselves.

Setting KEEP_PERMISSIONS=true lets these users opt out of the forced permission resets while keeping the safe default for everyone else.

How Has This Been Tested?

Tested locally with a bind-mounted /config directory whose files were set to custom permissions before container start:

• Without KEEP_PERMISSIONS (default): permissions on /config and ddclient.conf are reset to 700/600 on container start and on each config-file save — confirmed existing behavior is intact.
• With KEEP_PERMISSIONS=true: permissions on /config, /run/ddclient-cache, and ddclient.conf are left untouched on startup; touching ddclient.conf to trigger the inotify loop also leaves permissions unchanged. ddclient restarts correctly in both cases.

Test environment: Manjaro Linux, Docker, linux/amd64.

Source / References:

• Community reports of permission resets interfering with NFS and custom ACL setups
• Docker Mod approach considered but rejected — this is a minimal opt-in flag on core container behaviour, not a plugin concern

[github-actions]

Thanks for opening this pull request! Be sure to follow the pull request template!