[CRIU] [PATCH v2 2/4] Track which configuration options have been changed

[Pavel Emelyanov]

>> Trying to make config file become docker-transparend-cli doesn't just "looks wrong",
>> it's also problematic since fixing a global config would affect every single CRIU 
>> invocation that might happen in between. To get a "CLI/RPC overrider" we need
>> something, that it local to a single CRIU invocation... maybe another "local" or
>> "one-shot" config file, that CRIU will read after reading the global one and parsing
>> CLI/RPC. But can we tell CRIU where this one-shot file is through docker/lxd call?
> 
> Pavel, thanks for your comments, although I am not sure what you
> propose. So for RPC you basically say we do not want to have
> configuration files, right? 

Not exactly. We may still use them, but in the "low prio" mode, i.e. the options
passed via RPC shoudl take priority over those read from config.

> So should we merge the CLI patches?

Yes, since ...

> Everything concerning the CLI patches seems to be as everyone expects.

... this :)

> I guess I understand the 'one-shot' idea but I am also not sure how it
> should work. Maybe you are also not sure ;) 

Yup :( I remember the problem, but still have no good answer for it.

> We are looking for mechanism> to influence LXD (which uses CLI) and docker/runc (which uses RPC). But
> it should be different than configuration files, right?

My idea was to introduce two config files for criu. The first one is exsting one, that
criu reads from known global place (/etc/...). Then criu parses CLI/RPC options and 
overrides values read from config. Then should go the 2nd config, which is formatted
the same way as the 1st one, but it sits not in some other place path to which is
somehow (I don't know how to pass this knowledge "through" docker/lxd) told to criu
by the caller. This 2nd config file will override options set via CLI/RPC. Also, since
the path to this 2nd config file is specified by the caller, if some other criu invocation
happens in parallel it will not erroneously pick this file's options.

-- Pavel