proposal: add --no-delete to runc run

[tonistiigi]

runc run is much more simple to use than create/start async commands that are almost impossible to use safely without introducing a special shim-like binary to deal with SIGCHLD reaper issues.

One of the problems though is that when using run calling process can't get the full stats of the process because cgroups are already deleted when it returns. Could we consider adding --no-delete option that leaves cgroups and other resources in place so the caller can analyze them and then call runc delete to do the manual cleanup.

[lifubang]

+1

[kolyshkin]

Maybe --keep-cgroups? I'm not sure what are the other resources (except maybe intel RDT).

[lifubang]

Maybe --keep-cgroups? I'm not sure what are the other resources (except maybe intel RDT).

Besides cgroup paths, we should keep runc state dir to allow us use runc delete to delete the cgroup paths, so I'd prefer to use --no-delete.

[lifubang]

It's very easy to implement. Please see #2825 .

[lifubang]

As described in #2825 (comment)
We suggest change --no-delete to --keep.