[CRIU] [PATCH v5 2/3] Do not error out in RPC mode with wrong config file entries

[Andrei Vagin]

On Thu, Dec 27, 2018 at 02:07:56PM +0000, Radostin Stoyanov wrote:
> On 26/12/2018 21:42, Andrei Vagin wrote:
> >> Relates: https://github.com/checkpoint-restore/criu/issues/578
> >>
> >> If the config parser finds a unknown option in the configuration file,
> >> the wrong option is printed out and CRIU exits.
> >>
> >> In RPC mode this is not the best thing to do, as CRIU might not be able
> >> to print the message to the user.
> > It is a bad explanation, because with your first patch the user will see
> > errors. I am not sure why we need to ignore unknown options in config
> > files. It looks dangerous, because the user can do a typo and will not
> > notice it.
> >
> A user could make a typo and they should be able to notice it in the log
> file but
> if CRIU exits with an error, this will break the checkpoint/restore
> functionality of
> container engines.
> 
> An example of a software that has such behaviour is sshd. If a user
> makes a typo in
> the /etc/ssh/sshd_config file, after "systemctl restart sshd", they will
> no longer be
> able to connect via ssh. Although, for security reasons, the behaviour
> of sshd
> might be appropriate, I think that in the case of CRIU, showing a
> message, instead
> of exiting with an error, would be more user-friendly.

Yes and no. I understand the sshd reasons, but they can be applied to
criu restore, but not to criu dump, IMHO.

Our goal is to not loose states of processes:
1. criu dump doesn't have to be destructive:
  * in case of any error, processes have to continue running
  * it is better to fail rather than dump wrong or incomplete state

2. sometimes we really may want to restore processes even if there is
some problem

> 
> Radostin