Re: [gentoo-dev] rfc: generic "container" keyword for init scripts

[William Hubbs]

On Tue, Dec 01, 2015 at 03:28:44PM -0600, William Hubbs wrote:
> On Tue, Dec 01, 2015 at 11:21:49AM -0800, Zac Medico wrote:
> > On 12/01/2015 10:19 AM, William Hubbs wrote:
> > > On Tue, Dec 01, 2015 at 11:26:19AM -0600, William Hubbs wrote:
> > >> On Tue, Dec 01, 2015 at 09:00:55AM -0800, Zac Medico wrote:
> > >>> On 12/01/2015 08:50 AM, William Hubbs wrote:
> > >>>> The "container" keyword, being generic, would have its meaning expanded
> > >>>> to cover new container systems as they come along. This means if a
> > >>>> service script has the keyword "-container" it will not work under any
> > >>>> current or future container systems. On the other hand, adding
> > >>>> "container" means it will work under all of them.
> > >>>
> > >>> If it's similar to how license groups work, then there is room for doing
> > >>> things like "-@container docker" which means no containers except
> > >>> docker, or "@container -docker" which means all containers except
> > >>> docker. Keyword groups can be implemented using a simple expansion
> > >>> mechanism, just like license groups.
> > >>
> > >> Keyword groups are an interesting idea; I'll think about this approach.
> > >
> > > One question that comes to mind is,, who defines which keywords go in
> > > each group?
> > >
> > > The containers or virtualization systems themselves can be autodetected
> > > so they are the same everywhere, but keyword groups are not able to be
> > > detected.
> >
> > The groups should go in a configuration file somewhere. For example,
> > they could be defined in rc.conf with a variable setting like this:
> >
> > rc_keyword_group_container="docker lxc openvz vserver"
>
> If we keep the keywords as they are, I am starting to think we can just
> add a container keyword that would be valid for all of the containers;
> that way a script could be set up to work for no containers or for
> specific ones like we are talking about.
 
Here is where my thoughts are on this now. There will be a
"-containers" keyword, which will expand to list all of the containers
 we can detect on the operating system OpenRC is running on -- for
 example, on Linux it might be:

 "-docker -lxc -openvz -rkt -systemd-nspawn -vserver"

 So any time you list -containers as a keyword it would expand
 appropriately.

> OpenRC currently doesn't do any detection of virtual machines, so maybe
> that could be another expansion of this -- add a keyword "vm" and
> keywords for the virtual machines.
 
 VM's will be a separate project that I will look at later.

Thoughts?

William