Heya, On 20 April 2015 at 06:59, Adrian Reber <adr...@lisas.de> wrote: > Using CRIU I have been migrating processes from one system to another > for the last few months (even years). I am now interested in migrating > processes under systemd's control. Before starting to look how to make > it work I wanted to know if there has been any discussion if and how > systemd and CRIU can work together? > > Dumping a process under systemd's control should be no problem. > After criu has dumped the process (and killed it) systemd should know > that it does not need to restart the process, but even if the process is > restarted by systemd it does not hurt the process migration. > > The interesting part happens on the system where the process wants to be > migrated to. After the process has been dumped and transfered from the > source system to the destination system it needs to be restarted. So far > this works with different tested processes (postgresql is my current > test process). If I want to restore the process as a systemd child > process I have the problem that the process would have to be re-parented > to systemd after restarting which is not possible in Linux. Therefore I > need the help of systemd. > > My plan now would be to transfer the process to the destination > system and tell systemd I want to restore a process which should be > under systemd's control after the restore has completed. Therefore > systemd needs to run criu with the option to restore the new process as > a criu sibling. Thus systemd would be the correct parent process. > > Is this something which would be useful to integrate into systemd? > I have some ideas how this could be implemented and how the user > interfaces could look like. Before going in too much detail I want to > find out if this is a direction which makes sense.
So systemd has re-exec support. I would go down the route of trying to serialise the systemd state of the process as well on the orginal host, and then deserialise it on the target. I haven't done anything with re-exec serialisation on systemd yet, so no idea how sufficient that would be to "side-load" a process like that. It will be fragile. Going down the route of machinectl api / containers sounds more interesting. As there is more support for importing those. E.g. instead of importing a tarball and execing, it, one unfreezes it. -- Regards, Dimitri. Pura Vida! https://clearlinux.org Open Source Technology Center Intel Corporation (UK) Ltd. - Co. Reg. #1134945 - Pipers Way, Swindon SN3 1RJ. _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
