i/builtin: allow timeserver-control to manage per-link ntp settings via systemd-networkd

[andrewphelpsj]

This change enables the usage of timedatectl ntp-servers and timedatectl revert when a snap is connected to the timeserver-control interface.

Review usage of bus_network_mgr to see how these are used in timedatectl: https://github.com/systemd/systemd/blob/main/src/timedate/timedatectl.c

This is coming from a request from field.

SNAPDENG-36147

[Copilot]

Pull request overview

This PR extends the timeserver-control interface to support per-link NTP configuration through systemd-networkd. The changes enable snaps to use timedatectl ntp-servers and timedatectl revert commands by granting necessary D-Bus permissions to interact with systemd-networkd's Manager interface.

• Adds D-Bus permissions for SetLinkNTP, RevertLinkNTP, and GetLinkByName methods on the network1 Manager interface
• Implements test coverage for the new ntp-servers and revert subcommands
• Updates interface tests to verify the new AppArmor rules are properly generated

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
interfaces/builtin/timeserver_control.go	Adds D-Bus permission rules for systemd-networkd per-link NTP management
interfaces/builtin/timeserver_control_test.go	Adds test assertions to verify new D-Bus paths and methods in AppArmor snippets
tests/main/interfaces-timeserver-control/task.yaml	Adds integration tests for ntp-servers and revert commands when systemd-networkd is enabled

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[github-actions]

Thu Dec 18 17:35:07 UTC 2025
The following results are from: https://github.com/canonical/snapd/actions/runs/20343655611

Failures:

Preparing:

• openstack:ubuntu-core-24-64:tests/core/snapd-refresh

Executing:

• openstack:arch-linux-64:tests/main/interfaces-timeserver-control
• openstack:ubuntu-core-18-64:null
• openstack:ubuntu-core-18-64:null
• openstack:ubuntu-core-24-64:tests/main/dbus-activation-session
• openstack:ubuntu-20.04-64:tests/main/degraded
• openstack:ubuntu-20.04-64:tests/main/interfaces-timeserver-control
• openstack:ubuntu-24.04-64:tests/main/interfaces-timeserver-control

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.48%. Comparing base (1fed470) to head (ce86bd1).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #16378      +/-   ##
==========================================
- Coverage   77.82%   77.48%   -0.34%     
==========================================
  Files        1327     1339      +12     
  Lines      184888   183042    -1846     
  Branches     2438     2438              
==========================================
- Hits       143884   141830    -2054     
- Misses      32418    32615     +197     
- Partials     8586     8597      +11     

Flag	Coverage Δ
unittests	77.48% <ø> (-0.34%)	⬇️

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

The systemd-networkd detection logic is fragile. If systemd-networkd appears multiple times in list-unit-files output (e.g., systemd-networkd.service and systemd-networkd.socket), this will print multiple state values, potentially causing MATCH to fail unexpectedly. Consider using systemctl is-enabled systemd-networkd.service instead for a more reliable single-value check.

Suggested change

	if systemctl list-unit-files | grep systemd-networkd | awk '{print $2}' | MATCH "enabled"; then
	if systemctl is-enabled systemd-networkd.service 2>/dev/null | MATCH "enabled"; then

[Copilot]

This error message could be more actionable. It indicates a test configuration issue but doesn't explain why the test can't run or what the user should do. Consider clarifying that systemd-networkd is required but not enabled, e.g., 'systemd-networkd is not enabled but is required for per-link NTP command testing on Core 20+'.

Suggested change

	echo "Error: insufficient test coverage of timedatectl per-link NTP commands"
	echo "Error: systemd-networkd is not enabled but is required for per-link NTP command testing on Core 20+"