Mailinglist Archive: opensuse-features (368 mails)

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[openFATE 306411] Configuration files merge
  • From: fate_noreply@xxxxxxx
  • Date: Tue, 2 Jun 2009 10:00:50 +0200 (CEST)
  • Message-id: <feature-306411-5@xxxxxxxxxxxxxx>
Feature changed by: Michal Hrusecky (-miska-)
Feature #306411, revision 5
Title: Configuration files merge

openSUSE-11.2: New
Priority
Requester: Desirable

Requested by: Michal Hrusecky (-miska-)

Description:
If we want to make our distribution friendly even to advanced users, I
think that we shouldn't touch users configuration files. Luckily this
isn't problem as in spec file Ican state that this file is
configuration and I don't want to replace it if user did some manual
changes. Or I can say that I want to replace it and keep backup of
original one. But what I'm missing is some tool to easily merge these
files. In Gentoo there is etc-update
(http://www.gentoo.org/doc/en/handbook/handbook-amd64.xml?part=3&chap=4#doc_chap2)
or dispatch-conf (http://en.gentoo-wiki.com/wiki/Dispatch-conf) . I'll
describe more precisely what feature I'm missing and why I think it's
needed.
Let's say that I've got some package and there was quite big change in
package default configuration file which will affect most of the users.
On the other hand users can have pretty complicated constructions in
their configuration files and if they did something like that, it's
quite possible that they don't need to update their configuration file.
So it is needed to tell users that if they are experiencing problems it
is most likely because they touched default configuration. I can take
care of it manually, mention it in various README and such, but more
easier way would be following.
User installs some packages. At the end of zypper or yast installation
there will be warning "You've got 42 configuration files to merge,
please run etc-update/dispatch-conf/whatever". Then user will run some
easy interactive tool which will state which configuration files can
use some manual merging, it will allow user to see difference between
them and let him choose which one he wants or let him merge them
manually somehow. Same warning about unmerged configuration files
should appear each time user installs something, no matter if this
installation didn't add any conflict, until all conflicts are fixed.
User will be warned about possible problems, hacker can play with it
and keep his changes against distribution defaults and ordinary user
will just click on "use distribution default for all" if he ever
encounter such a problem (shouldn't happen as ordinary user wouldn't
touch configuration files).
I explained basic expected work flow, so now what I think should be
supported:
* detect configuration files, their conflicts and allow their merge -
this shouldn't be a big problem as rpm already stores conflicting files
as .rpmnew/.rpmold
* we probably want to keep even old versions to support three way merge
to achieve even better results
* if we are already storing these configuration files, maybe we should
let users to backup their own changes as well, add support for
versioning these configuration files
* warn user that he has conflicts in configuration files - will require
a little bit yast/zypper integration
* merging tool should support both console and graphical interface
(maybe use yast as possible frontend)
* support for various formats (expandable by plugins) - ordinary diff
may not be the best tool for merging XML files or ini files
* ordinary user who don't change anything shouldn't need to know about
this tool

Relations:
- Debian-like dist-upgrade live system full version upgrade
(feature/id: 305634)

+ Discussion:
+ #1: Michal Hrusecky (-miska-) (2009-06-02 09:49:38)
+ I was thinking about this a little bit more and if we want to support
+ some kind of versioning and we want to use plugins for getting
+ differences, it may be a good idea to request that plugins will be
+ capable not only of producing nice output of difference between
+ configuration files, but it probably should be able to apply it (behave
+ not only as a 'diff', but also as a 'patch'). And we can build some
+ simple version control system on top of it.
+ Advantages:
+ * can handle non-plain text files better (via plugins)
+ * we can implement feature to discard or merge several commits into one
+ to save space/make commit log more readable
+ * can handle nicelly even insane configuration files like sqlite
+ database or compressed directory with configuration files or any other
+ binary format
+ Disadvantages:
+ * probably worse handling of text files
+ * another thing to maintain/possible source of bugs




--
openSUSE Feature:
https://features.opensuse.org/306411

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