1 Technical_Decomp_Systemd

Miguel Jacq edited this page 2025-12-27 20:55:18 -06:00

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Table of Contents

• enroll/systemd.py
• UnitInfo (dataclass)
• Purpose: parsed subset of systemctl show for services.
• Fields:
• Lifecycle / where it’s used:
• UnitQueryError (exception class)
• Purpose: a structured error when systemctl show fails for a unit.
• Fields set in init:
• Message:
• Lifecycle / where it’s used:
• TimerInfo (dataclass)
• Purpose: parsed subset of systemctl show for timers.
• Fields:
• Lifecycle / where it’s used:

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enroll/systemd.py

UnitInfo (dataclass)

Purpose: parsed subset of systemctl show for services.

Fields:

• name: unit name
• fragment_path: main unit file path
• dropin_paths: list of drop-in config files
• env_files: resolved EnvironmentFiles entries (minus leading -)
• exec_paths: parsed executable paths from ExecStart
• active_state, sub_state, unit_file_state, condition_result

Lifecycle / where it’s used:

• Returned by get_unit_info().
• harvest.harvest() uses it to:
  • infer packages (dpkg_owner on fragment + exec binaries)
  • add /etc/... candidates from dropins/env files

---

UnitQueryError (exception class)

Purpose: a structured error when systemctl show fails for a unit.

Fields set in init:

• unit: unit name that failed
• stderr: trimmed stderr text

Message:

systemctl show failed for :

Lifecycle / where it’s used:

Raised by get_unit_info() if systemctl returns nonzero.

harvest.harvest() catches it and records a ServiceSnapshot with empty packages/files and a note containing the error string.

---

TimerInfo (dataclass)

Purpose: parsed subset of systemctl show for timers.

Fields:

• name
• fragment_path
• dropin_paths
• env_files
• trigger_unit: parsed from Unit= field (what the timer triggers)
• active_state, sub_state, unit_file_state, condition_result

Lifecycle / where it’s used:

Returned by get_timer_info().

harvest.harvest() uses timers to attribute timer override files under /etc to:

• the triggered service role (preferred), else
• a package role, else
• let it fall through and potentially get captured by etc_custom.