plugins/reboot: fix boot time command for FreeBSD

[ckoehne]

SUMMARY

The boot time is not a fixed value [1]. It's adjusted by NTP. That's not only an issue of FreeBSD. E.g. OpenBSD has the same issue [2]. On FreeBSD we can use the boot_id sysctl [3]. Unfortunately, OpenBSD doesn't have such a sysctl. So, we keep the boottime for now.

[1] https://cgit.freebsd.org/src/commit/?id=a512d0ab009eedf2f1876fce86d6386bfee626d8
[2] https://github.com/openbsd/src/blob/dd1c5868edaa80b7ad9df54e8b3eae1c49c42319/sys/kern/kern_tc.c#L735
[3] https://cgit.freebsd.org/src/commit/?id=34086d5bda29cc583755fc8948f59c3b61f8ce7d

ISSUE TYPE

• Bugfix Pull Request

ADDITIONAL INFORMATION

[ckoehne]

Note that the sysctl is not available on FreeBSD 12. Not sure if it's important. Additionally, FreeBSD 12 reaches EOL in a few days: https://www.freebsd.org/security/#sup

[webknjaz]

Note that the sysctl is not available on FreeBSD 12. Not sure if it's important. Additionally, FreeBSD 12 reaches EOL in a few days: https://www.freebsd.org/security/#sup

@ckoehne we don't run FreeBSD 12 in CI for the devel branch, but I think that some older stable and still supported versions do (stable-2.15 and older). This effectively means that we can accept a backport into the stable-2.16 branch for as long as it's framed as a bugfix.

Generally, we prefer having regression tests bundled with PRs. There's pre-existing ones @ https://github.com/ansible/ansible/blob/devel/test/units/plugins/action/test_reboot.py / https://github.com/ansible/ansible/tree/devel/test/integration/targets/reboot.

Do you think it would be possible to come up with an integration test? Keep in mind, though, that reboots are expensive so it's probably cheaper to piggy-back on one of the pre-existing tests. I moved some of the older ones to unit-tests to cut the CI usage some time ago.

[webknjaz]

Note that this appears in the changelog, along with other entries. Release notes generally refer to things that changed compared to the previous release. In that context, the end-users (the main target audience reading the changelog) wouldn't understand what's "the current one" in that context.

Could you try re-phrasing it? Using the past tense or structures like "X is now Y" may be helpful.

[ckoehne]

Note that the sysctl is not available on FreeBSD 12. Not sure if it's important. Additionally, FreeBSD 12 reaches EOL in a few days: https://www.freebsd.org/security/#sup

@ckoehne we don't run FreeBSD 12 in CI for the devel branch, but I think that some older stable and still supported versions do (stable-2.15 and older). This effectively means that we can accept a backport into the stable-2.16 branch for as long as it's framed as a bugfix.

Generally, we prefer having regression tests bundled with PRs. There's pre-existing ones @ https://github.com/ansible/ansible/blob/devel/test/units/plugins/action/test_reboot.py / https://github.com/ansible/ansible/tree/devel/test/integration/targets/reboot.

Do you think it would be possible to come up with an integration test? Keep in mind, though, that reboots are expensive so it's probably cheaper to piggy-back on one of the pre-existing tests. I moved some of the older ones to unit-tests to cut the CI usage some time ago.

I'm not sure if it's possible to reproduce it reliable. It's a sporadic issue which only occurs when:

1. ansible calls ssh target@ip shutdown -r
2. FreeBSD updates the system time e.g. due to NTP -> boot time changes
3. ansible is able to reconnect before the target rebooted -> ansible thinks that the target already rebooted
4. The target reboots

So, we would have to somehow delay the shutdown and then changing the system time after calling shutdown.