[Planetlab-devel] 2.6.17

[Mark Huang]

Kevin Atkinson wrote:
> I thought the idea was that all local changes should go in the file 
> plc_config.xml.  So are you saying that now when ever we upgrade, we 
> have to make a note of the local changes we made to plc_config.xml.  
> Remove it. Allow it to be recreated, than put the local changes back 
> in?  I hope you are planning to fix this.

No. We discussed this issue a few months ago and Thierry proposed the algorithm
that is used today:

http://lists.planet-lab.org/pipermail/devel/2006-April/001480.html
http://lists.planet-lab.org/pipermail/devel/2006-April/001485.html

Basically, plc_config.xml is a cache of current values. It is built by merging
/etc/planetlab/default_config.xml, anything in /etc/planetlab/configs/*, and
lastly, current values in /etc/planetlab/plc_config.xml. This is done
specifically to support exactly what you are trying to accomplish, merging in
your local customizations. Instead of munging /etc/planetlab/plc_config.xml with
a sed script, store your overrides as well-formed XML in
/etc/planetlab/configs/*, blow away /etc/planetlab/plc_config.xml, and let PLC
startup re-generate it.

FYI, my pseudo-code in 001485 is slightly wrong and should include
/etc/planetlab/plc_config.xml as the last file to merge. See myplc/guest.init in
CVS for the real code.

--Mark