linux registry (no, not that again!)
Rafael Garcia Leiva
angel.leiva at uam.es
Wed Jul 28 14:40:47 UTC 2004
On Tuesday 27 July 2004 19:15, Neal D. Becker wrote:
> Yes, here's the linux registry topic again. This project looks
> interesting. Any comments?
Yes, many comments!
I think that almost everybody will agree that Linux needs a different approach
to store configuration information for the system, applications and users,
other than the traditional configuration files under /etc. The problem is
that we do not agree how this new approach should look like. Perhaps,
everybody agrees that it must be a kind of local centralized system with a
common framework for accessing configuration information.
Regarding to this new "Linux Registry" proposal, I see many problems:
* It provides a system namespace but, how the information is organized? Does
every application have its own registry subset? What if two or more
applications share configuration values? Shall they duplicate configuration
information?
* "It is not an alternative to network information systems": fine, but it
should take into account that most of the Linux boxes are networked machines,
and presumably, centrally managed. So it should provide a (optional)
mechanism for the synchronization with a central networked configuration
database.
* "It doesn't know a thing about the semantics of each data it stores": this
is a bad thing because we cannot validate configuration information. It
assumes that the registry administrator knows what he is doing, and people
does not makes mistakes when typing.
* It expects to rewrite all the applications to use the new framework. This is
not realistic.
I think that "Linux registry" is a nice step in the right direction, but if we
have to change /etc, and change a lot of the already existing code, we should
try to do it in the right way, and provide a much more powerful solution.
I your are interested, you can take a look to the solution that the quattor
project (see http://www.quattor.org) proposes. Quattor has not been designed
as a replacement of the /etc directory, but it can be in the future. Among
the advantages the quattor's local Configuration Cache Manager
(http://hep-proj-grid-fabric-config.web.cern.ch/hep-proj-grid-fabric-config/documents/cache-spec.pdf)
has with respect of the Linux Registry I can mention:
* It provides a "User
Conventions" (http://quattor.web.cern.ch/quattor/documentation/docs/PanUserConventions.pdf)
document as a proposal for a standard to how to organize configuration
information.
* It provides the NVA-API library
(http://hep-proj-grid-fabric-config.web.cern.ch/hep-proj-grid-fabric-config/documents/nva.pdf),
to read configuration information (current implementation is in Perl)
* It provides a set of wrapper "configuration components" that reads the
cached configuration information and create traditional configuration files.
This eases the adoption of the new technology.
* It has a high level configuration language (called pan), that uses a much
powerful syntax than these key-value pairs to describe configuration
information, and it lets the system manager to perform validations (and then,
it is compiled into an internal key-value pairs format)
* It can be used in a networked environment to keep the configuration
information centralized.
I do not pretend to convice everybody to move to quattor, what I want to say
is that we need a much powerful approach that this simple Linux Registry.
Cheers
--
Rafael Angel Garcia Leiva
Universidad Autonoma Madrid
http://www.uam.es/angel.leiva
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