This app shows realtime energy readings from /proc/energy/cgroup provided by the ProcPower kernel extension.

1. Copy this folder to your Nextcloud apps/ directory as sustainability/.

2. Ensure the web server user can read /proc/energy/cgroup (often world-readable; otherwise use group perms or an ACL). No setuid needed.

3. Enable the app:

   sudo -u www-data php occ app:enable sustainability

4. As an admin, open Nextcloud and click Sustainability in the left sidebar.

• The navigation page and /apps/sustainability/energy endpoint are admin-only. Non-admins get HTTP 403/blank.
• Chart.js is bundled; no external CDN required (CSP-safe).
• CSRF: requests include the requesttoken header automatically via OC.requestToken.

• File path is fixed to /proc/energy/cgroup for now. To make it configurable, add an admin settings form and persist a path in the app config via \OCP\IConfig with validation (absolute path, max length, no ..).
• Poll interval defaults to 1000 ms in js/main.js.
• Keep last 300 points (~5 minutes).

• If the chart shows "File not readable", confirm ProcPower is installed and the webserver (e.g., www-data) can read the file.
• Use tail -f /proc/energy/cgroup on the host to verify it updates.
• Check Nextcloud logs: data/nextcloud.log.