[AG-DEV] Re: Location of AG config files

Tobias Schiebeck Tobias.Schiebeck at manchester.ac.uk
Mon Sep 15 04:46:51 CDT 2008


Hi,

On Sat, 2008-09-13 at 14:50 +1000, Christoph Willing wrote:
> On 12/09/2008, at 5:41 PM, Tobias Schiebeck wrote:
> 
> > Hi,
> >
> > Beeing a Debian user for some years now, I know that Debian has
> > sometimes strange ideas how to package things. On the other hand I was
> > slightly surprised to find "code" such as the SharedPresentation
> > implementation under /etc . IMHO /etc is the place for config files  
> > and
> > thats what I think Debian is trying to enforce (which I don't think is
> > the right thing to do but ...)
> >
> > On Thu, 2008-09-11 at 07:55 -0500, Thomas D. Uram wrote:
> >> Chris:
> >>
> >> What's the chance that a future change will also impact files under
> >> /usr/share, requiring another adjustment?  Is there any guidance from
> >> the debian/ubuntu community about how to adjust, or where such files
> >> should be placed?
> >>> (One way around this would be to create a single mega-package of  
> >>> AG &
> >>> related service packages, but I feel it would be an unsatisfying, if
> >>> not "wrong", solution)
> >> I agree that this is not the right way to go.
> >
> > I think /usr/share is where the NodeServices and other "code"  
> > should be
> > placed and should be fairly safe from changes. The pure configuration
> > files such as the nodeConfig could stay under /etc as it would be
> > recreated if it isn't there, and /etc is the place where people  
> > look for
> > these general configuration stuff.
> 
> 
> I agree that this is the correct way to go.
> 
> However splitting these files into separate locations entails more  
> work to implement compared with having them all in /etc or all in / 
> usr/share - having them all in one place means just a single line of  
> code needs to be changed (the definition of AGTkBasePath).
> 

I think this split up is a long term solution. In the short term a move
to /usr/share should be safe as we can declare the configuration files
as software essentials ;-). 

> If we now have a separate location for some of the files (I suggest  
> the Services, NodeServices and SharedApplications directories), then  
> we'd need not just an additional variable defining the new location,  
> but also changes to any current code which assumes the old locations.  
> For instance, convenience functions like GetSharedAppDir() themselves  
> call GetBaseDir() which would now return the wrong location;  
> something to replace GetBaseDir() is needed in all these cases.
> 
> 
> If we decide to go ahead with something like this, the next question  
> is who will implement it? I'm prepared to do it but the changes touch  
> on reasonably fundamental bits of AG internals so perhaps it is best  
> left to Tom ... ?
> 
> Either way, Debian Lenny is currently frozen in the lead up to being  
> released. It would be good to have any AG changes fully in place by  
> the time Lenny is released.
> Similarly, Ubuntu 8.10 is due in October.

I don't think there is a need to rush things trough to change internal 
structure for these a move should solve the problems of the file deletion

Tobias
> 
> >> On 9/8/08 6:37 PM, Christoph Willing wrote:
> >>> Tom,
> >>>
> >>> There is a problem with the Debian & Ubuntu AG packages. The  
> >>> revamped
> >>> build tool mechanisms introduced early this year to accommodate
> >>> multiple python versions on the same machine has an unfortunate side
> >>> effect; anything under /etc is considered to be owned by a  
> >>> particular
> >>> package and is removed completely during upgrades or  
> >>> reinstallations,
> >>> regardless of whether another package may be using the same area.
> >>>
> >>> In the case of the AG installation, a number of configuration files
> >>> are kept in directories under /etc/AccessGrid3. In particular,
> >>> /etc/AccessGrid3/NodeServices normally contains the standard Audio &
> >>> Video Services. However other packages may want to install services
> >>> there too e.g. vpcscreen, aghdvic. Initial installation of these
> >>> packages works OK but if the AG package is reinstalled or upgraded,
> >>> the additional services are also removed.
> >>>
> >>> (One way around this would be to create a single mega-package of  
> >>> AG &
> >>> related service packages, but I feel it would be an unsatisfying, if
> >>> not "wrong", solution)
> >>>
> >>> This (new) unwanted behaviour occurs because of the special  
> >>> treatment
> >>> given to files/directories under /etc, so an solution is to use a
> >>> different location. I have done some testing using
> >>> /usr/share/AccessGrid3 instead of /etc/AccessGrid3 as a location for
> >>> the config files. With this new location, any number of  
> >>> installations,
> >>> reinstallations etc. of the AG  & related packages can now be
> >>> performed without any interference to each other. Introducing the  
> >>> new
> >>> location is trivial - a single line patch to the toolkit code  
> >>> itself,
> >>> as well as a single line change in the packaging script of each
> >>> affected package (accessgrid3.x, vpcscreen, aghdvic, etc.)
> >>>
> >>>
> >>> Since this is a Debian & Ubuntu specific problem, I don't expect  
> >>> that
> >>> relocating /etc/AccessGrid3 needs to apply to all distributions
> >>> (although it may be worth considering). However before I release any
> >>> packages with the new file layout, do you have strong feelings about
> >>> the proposed solution - or alternative solutions?
> >>>
> >>> I've cc'd to AG-DEV in case someone more conversant with Debian/ 
> >>> Ubuntu
> >>> Policies & packaging practices can offer advice; please chime in  
> >>> - I'm
> >>> just a part-timer in this area and I'm keen to receive suggestions.
> >>>
> >>>
> >>>
> >>> chris
> >>>
> >>>
> >>> Christoph Willing                        +617 3365 8350
> >>> QCIF Access Grid Manager
> >>> University of Queensland
> > -- 
> > ---------------------------------------------------------------------
> > Tobias Schiebeck                    tobias.schiebeck at manchester.ac.uk
> > Research Computing Services           http://www.rcs.manchester.ac.uk
> > The University of Manchester                  tel: (+44) 161-275-0601
> > ---------------------------------------------------------------------
> >
> >
> 
> Christoph Willing                        +617 3365 8350
> QCIF Access Grid Manager
> University of Queensland
> 
-- 
---------------------------------------------------------------------
Tobias Schiebeck                    tobias.schiebeck at manchester.ac.uk
Research Computing Services           http://www.rcs.manchester.ac.uk
The University of Manchester                  tel: (+44) 161-275-0601
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