[CRIU] CRIU and GO

[Adrian Reber]

On Tue, Oct 02, 2018 at 07:18:21PM -0700, Andrei Vagin wrote:
> On Tue, Oct 02, 2018 at 08:17:01AM +0200, Adrian Reber wrote:
> > Hello Andrei,
> > 
> > I am currently trying to add checkpoint/restore support to podman:
> > 
> > https://github.com/containers/libpod/pull/469
> > 
> > and I hope it will soon be merged. As I need at least CRIU 3.11 for
> > podman I would like to include a version check into podman.
> > 
> > As we already have a version check in GO in runc I was first looking at
> > the runc code but then I remembered the Pavel's CRIU go interface in
> > lib/go/.
> > 
> > So for podman I tried to vendor-in github.com/checkpoint-restore/criu
> > and started to wonder if we might want to have an independent GO
> > binding, because right now most of the vendor-in'd code is C code and
> > tests and not much GO code.
> 
> Is it impossible to vendor only github.com/checkpoint-restore/criu/lib/go/src/criu?

Hmm, the tool used to manage the vendoring (vndr) keeps all the .c files
around. If manually managing the vendor tree it would probably be
possible, but using the tool it is not. But I hardly have any
experience how to manage a GO project. Right now I get:

$ du -hs vendor/github.com/checkpoint-restore/criu
5.8M	vendor/github.com/checkpoint-restore/criu

It just seems easier to detect the CRIU GO bindings if they would be a
separate repository, especially as it probably can live with a
completely different and much slower release schedule. Most changes
to CRIU are not necessarily necessary in the GO bindings. Right now the
GO code is buried in a lot of C code which the vndr tool does not delete
as it could be a cgo file.

> > So instead of including 'github.com/checkpoint-restore/criu/lib/go/src/criu'
> > we could have something like 'github.com/checkpoint-restore/go-criu' ?
> > 
> > What do you say? Would it make sense to have an independent go binding
> > for CRIU? Once it works we could start to also use it in runc...

The main idea was to have a canonical location for the go bindings which
is easy to detect and switch runc to using it once it exists. I would
like to use it in podman right now and the vendor/github.com tree is
around 20MB of which 5MB is CRIU. It basically is only a tool problem
(vndr), but it probably is more difficult to change the tool, then
provide CRIU go bindings separately.

		Adrian