Re: [PATCH RFC 0/3] Add checkpoint/restore support to LXC using CRIU

Hi Michal and Martin, Thanks for your reply. Just an explanation. I'm not interested directly in developing this specific feature. If there is a GSoC student addressed to this... Excellent. I'm interested in developing snapshot and container migration which unfortunately requires this feature. Unless you have another opinion.

-- Julio Faracco Em qui., 1 de abr. de 2021 às 07:33, Michal Privoznik <mprivozn(a)redhat.com&gt; escreveu: > > On 4/1/21 12:01 AM, Martin Kletzander wrote: > > On Sat, Feb 27, 2021 at 01:14:29AM -0300, Julio Faracco wrote: > >> Hi guys, > >> > > > > Hi and sorry for not replying earlier. > > > > Yeah, sorry. I have this marked for review and yet still haven't done so. > > >> I marked this series as RFC to discuss some points. I'm interested in > >> enhancing this specific part of LXC. So, some questions that I would > >> like to hear as a feedback from community: > >> 1. I decided to use a tar to compress all CRIU img files into a single > >> file. Any other suggestions? > >> 2. If no is the answer to question above, is there a consensus on > >> preferring to use command line calls or libraries? I would like to use > >> libtar for instance. I personally think that this approach is ugly. > >> Not sure if I'm able to do that. The same for CRIU. > > > > I remember that for CRIU, back when we were trying to do that, the issue > > was that the commands were not atomic, did not properly report error > > messages and maybe something more along the lines. Either there was no > > library interface or it was not MT-safe, basically there were couple of > > issues like that which we were not able to deal with. > > > > I do not really remember all the details. Maybe Michal does as I think > > he suggested the idea back then. I Cc'd him. In the worst scenario we > > will need to figure this all out again ;) > > IIRC the main problem was that we wanted CRIU to be able to send its > data over a TCP connection. Back then, when a GSoC student was looking > at this, CRIU was only able to store data into a file (or even multiple > files in a directory?) and wasn't able to create server/client > connection. Maybe this has changed since then? If not, then we can use > tar, sure. And to transfer data we can use so called tunnelled > migration, where the migration stream is sent over libvirt connection > rather than directly to the other side (because then we would have to > have nc or similar involved). > > https://libvirt.org/migration.html#transporttunnel > > Another issue was that it couldn't handle all namespaces (but I'm not > certain - it was 5 years ago). > > But let me find some time and review patches. > > Michal >