Subject: Re: Using git to store /etc, redux

From: David Härdeman <[email-masked]>
Date: Sun, 20 May 2007 11:48:35 +0200

On Sat, May 19, 2007 at 04:37:54PM -0700, [email-masked] wrote:
>On Sat, 19 May 2007, David Härdeman wrote:
>
>>I recently had the idea to store and track /etc using git. When googling 
>>the topic I came across the "Using git to store /etc" thread from the end 
>>of last year which provided some interesting details on what would be 
>>necessary.
>>
>>It seems the file metadata (owner, group, mode, xattrs, etc) was the big 
>>stumbling point, so I wrote up a tool over the last few days which allows 
>>the metadata to be stored in a separate file which can be stored along 
>>with the rest of the data in the repo (or separately).
>>
>>This is also useful for tripwire type checks and for other types of 
>>storage which drops some of the metadata (tar comes to mind)...
>>
>>The tool (metastore) is available from: git://git.hardeman.nu/metastore.git
>>
>>Not completely cleaned up yet (it lacks a real README and some Makefile 
>>targets) but I hope it might be useful to others (it sure is to me).
>>
>>Please CC me on any replies.
>
>as I understand the issue, the problem isn't creating a tool to store the 
>metadata, but in integrating things with git.

That is also important of course, the problem is that there are many 
different scenarios for how people might want to work with the metadata 
(e.g. whether changed metadata should be stored automatically or only 
with user interaction, etc).

For the "store /etc in git" solution which is what got me into this, it 
might be enough to have a pre-commit hook if all changes are made in 
/etc and committed to /etc/.git periodically (meaning there are no real 
checkouts to speak of).

>when checking something in a pre-commit hook needs to run the tool to 
>store the data.
>
>git supports this and it's pretty simple to do this.

Yes, I already have hook scripts in my local setup which does this, 
it was not clear whether pre-commit hooks could change the commit by 
adding more files to be committed but it seems to work, essentially 
the pre-commit hook is just:

metastore -s
git-add .metadata

>however when checking things out there are approaches
>
>1. modify git to have a post-checkout hook to set the metadata to match
>    what was stored at checkin and accept the fact that this leaves a
>    window where the file has the wrong metadata on it (between when the
>    file is written and when the hook runs), or use a staging area to have
>    copies of the files during check-in and check-out

Right, I use a non-hook script for this right now which changes umask to 
0077, pulls the changes, shows the difference in metadata and asks for 
confirmation and then applies the metadata (which undoes the effects of 
the umask setting).

I think I'll add both scripts to my git repo as examples soon.

-- 
David Härdeman