feat(chrony): introducing the chrony module

[aafeijoo-suse]

This new module relies on chrony to add support for NTP in the initrd. By default, it also uses NTP sources from DHCP.

It provides two new kernel command line options:

• rd.ntp: it can be used multiple times to specify server, pool and peer time sources.
• rd.ntp.nodhcp: it disables the use of NTP sources from DHCP.

In some environments, it's necessary to fetch live images from HTTPS URLs. The problem is that the hardware clock may be off, so the validation of the SSL certificates may fail if the time is out of sync. Also, some systems may not have access to DHCP for security reasons, that's why we need a way to configure them on the kernel command line.

Notes:

• chrony upstream only provides systemd services and configuration as examples, so there are many differences between the distributions.
• While it might make sense to use /var on the host, let's try to use /run in the initrd, so everything can persist after switching root.

Checklist

• I have tested it locally
• I have reviewed and updated any documentation if relevant
• I am providing new code and test(s) for it

[devkontrol]

Would it be reasonable to add test case for this new dracut module ?

so the validation of the SSL certificates may fail

Does this happen already on the CI ? Can we trigger it with some test ?

[aafeijoo-suse]

Would it be reasonable to add test case for this new dracut module ?

Upstream has 143 modules and 24 tests. There is already a module providing NTP without a test (well, systemd-timesyncd only provides simple NTP). I can't find a rule of thumb, some of the latest additions do not have a test: devicetree-firmware, memdisk, simpledrm, systemd-battery-check, hwdb, pcmcia, numlock, systemd-bsod... Furthermore, adding tests can take ages (see my PR adding tests for systemd-sysext).

so the validation of the SSL certificates may fail

Does this happen already on the CI ?

I don't think so. The real use case for this module is an OS installer image, downloaded remotely from the initrd. We need a way to specify NTP in the initrd before fetching the image over HTTPS, otherwise, in isolated systems with an out of sync clock the fetch may fail and the OS could not be installed.

Can we trigger it with some test ?

I guess an HTTPS server with an expired certificate could be simulated. But... I'm not sure if it makes sense to test this in the CI.

[devkontrol]

some of the latest additions do not have a test: devicetree-firmware, memdisk, simpledrm, systemd-battery-check, hwdb, pcmcia, numlock, systemd-bsod

None of these dracut modules maintain a dedicated .service file - they all just copy the .service file that is maintained by other project. This PR however introducing a new .service file (and .conf file) that this project would have to maintain.

Could we pick up the .service file and .conf file from the host instead ?

chrony upstream only provides systemd services and configuration as examples, so there are many differences between the distributions.

This PR suggests that dracut would now maintain distribution-independent service file without a test.

[aafeijoo-suse]

None of these dracut modules maintain a dedicated .service file - they all just copy the .service file that is maintained by other project.

And that does not mean that they work with dracut, usually because dracut is not installing all required dependencies, binaries, kernel modules, configuration... Also, there are some dracut modules that install modified versions of systemd services via sed without a test (bluetooth, dbus-daemon, dbus-broker).

This PR however introducing a new .service file (and .conf file) that this project would have to maintain.
Could we pick up the .service file and .conf file from the host instead ?

No, we can't, for the reasons explained in the notes of the PR description, plus although the systemd services were the same on the host in all distros, they are not implemented to work in the initrd (the Install section cannot be overridden and it has a WantedBy=multi-user.target).

This PR suggests that dracut would now maintain distribution-independent service file without a test.

I don't see why that is a big deal here, most of the merged code is not being tested. But anyway, I'll add one test if that is the only objection to this PR.

[Conan-Kudo]

I would prefer some tests for this module, please.

[bdrung]

I would like to see code tested as well: either get those services upstream and test it there; or add a test case in dracut.

[aafeijoo-suse]

Draft until the CI has #2418

[devkontrol]

There is already a module providing NTP without a test

I think this is not the case as TEST-41 includes systemd-network-management, which than includes systemd-timesyncd. Perhaps NTP functionality is not tested/confirmed, but at the CI would break without systemd-timesyncd