ci: run poller as www-data to avoid RRD ownership errors

[TheWitness]

The poller currently runs via 'sudo php poller.php' (root). This activates a root-only ownership-reassignment code path in Cacti's rrdtool_function_create() (lib/rrd.php): after creating the first-run RRDs for the default 'Local Linux Machine' graphs, it logs 'RRD file ... does not exist for ownership assignment' as an ERROR, which the 'Check Cacti Logs for Errors' step then treats as a hard CI failure.

Fix: re-apply www-data ownership immediately before polling and run the poller as www-data (sudo -u www-data) instead of root, so that root-only ownership-reassignment branch never triggers.

Same pattern already verified working in plugin_evidence/plugin_flowview/plugin_wmi etc.

[Copilot]

Copilot review overview

🟢 Approval recommended

The workflow changes address the CI ownership errors without unresolved issues.

Review effort: Lite
Findings: None

What changed in this PR

Updates CI polling to run as www-data, avoiding root-only RRD ownership errors.

Changes:

• Re-applies ownership and permissions before polling.
• Runs poller.php as www-data.

File	Description
.github/​workflows/​plugin-ci-workflow.yml	Adjusts permissions and poller execution user.

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[jdcoats]

this sounds odd to me as it seems like you are making Cacti Linux flavor specific. Many systems may not even have www-data and use apache:apache or any other variant. My files are apache and poller runs as root.