[Sisuite-devel] Revision control for image chroot

[Bernard Li]

Does anybody have a suggestion on a revision control system for
SystemImager images (chroot)?

Does anybody even want such a feature?

I am thinking along the lines of recording what files have been
changed when and being able to roll back to previous revisions etc.
You could keep entire backups of your entire image, but that eats up a
lot of space quickly if your image is big.

SVN seems like an overkill, since you probably just want the revision
control bits to be local to the system (included in the image), plus
it probably cannot handle file ownership correctly (not to mention
treat special files in /dev).

RCS may be a good way to implement this. Also some sort of
LVM/snapshot mechanism can be used.

Any thoughts on this topic?

Cheers,

Bernard

[Andrea Righi]

Post by Bernard Li
Does anybody have a suggestion on a revision control system for
SystemImager images (chroot)?
Does anybody even want such a feature?
I am thinking along the lines of recording what files have been
changed when and being able to roll back to previous revisions etc.
You could keep entire backups of your entire image, but that eats up a
lot of space quickly if your image is big.
SVN seems like an overkill, since you probably just want the revision
control bits to be local to the system (included in the image), plus
it probably cannot handle file ownership correctly (not to mention
treat special files in /dev).
RCS may be a good way to implement this. Also some sort of
LVM/snapshot mechanism can be used.
Any thoughts on this topic?
Cheers,
Bernard

Bernard,

have you seen this?

http://www.nongnu.org/rdiff-backup/index.html

We could implement a versioning mechanism using this tool, maybe saving
incremental changes in /var/lib/systemimager/backups or similar... since
it supports also remote server backups the user could choose also to
push backups to an external machine to have a mirror image server, or
similar stuff...

Moreover the package seems to be already included in SuSE, Fedora,
Debian, etc...

See also this howto: http://www.howtoforge.com/linux_rdiff_backup

Cheers,
-Andrea

[Bernard Li]

Hi Andrea:

This is a great idea! I think we can definitely build upon this tool.

I would like to keep revision notes, and I do not see this capability
with rdiff-backup, perhaps we can implement a sqlite backend (or a
text file...?) to keep revision logs.

Here are some ideas of operations:

si_rci st: rdiff-backup --compare <image> <backup>
si_rci log: rdiff-backup --list-increments <backup>
si_rci ci: rdiff-backup <image> <backup>
si_rci revert: rdiff-backup --restore <image> <backup>
si_rci restore 1: rdiff-backup --force --restore-as-of 1B <backup> <image>
...

(Here, rci stands for Revision Control for Image :-) )

I would also like to tie this in with a si_chroot wrapper, which
basically runs like:

si_chroot <image_name>

and would wrap chroot. It will also ensure that once you exit from
the chroot, your modifications are automatically checked in.

I tested this on Fedora Core 6 VMWare on a 1GB image, the operations
did not take too long. This really looks promising. I will try to do
some tests tomorrow with real hardware...

Sounds like an IRC brainstorming session is in order ;-)

Cheers,

Bernard

Post by Andrea Righi

Post by Bernard Li
Does anybody have a suggestion on a revision control system for
SystemImager images (chroot)?
Does anybody even want such a feature?
I am thinking along the lines of recording what files have been
changed when and being able to roll back to previous revisions etc.
You could keep entire backups of your entire image, but that eats up a
lot of space quickly if your image is big.
SVN seems like an overkill, since you probably just want the revision
control bits to be local to the system (included in the image), plus
it probably cannot handle file ownership correctly (not to mention
treat special files in /dev).
RCS may be a good way to implement this. Also some sort of
LVM/snapshot mechanism can be used.
Any thoughts on this topic?
Cheers,
Bernard

Bernard,
have you seen this?
http://www.nongnu.org/rdiff-backup/index.html
We could implement a versioning mechanism using this tool, maybe saving
incremental changes in /var/lib/systemimager/backups or similar... since
it supports also remote server backups the user could choose also to
push backups to an external machine to have a mirror image server, or
similar stuff...
Moreover the package seems to be already included in SuSE, Fedora,
Debian, etc...
See also this howto: http://www.howtoforge.com/linux_rdiff_backup
Cheers,
-Andrea

[Paul Jackson]

Post by Bernard Li
I would like to keep revision notes, and I do not see this capability
with rdiff-backup

I don't see why one has to integrate the backup and the revision notes
facilities.

If one has a file in which one just adds dated revision notes, and that
file is part of what gets backed up, then all we'd need (that I can see)
in addition is an easy way to display an annotated version of that file,
so one could see when changes or additions were made to that notes file.

I'm always in favor of "one more simple utility", over trying to integrate
two separate non-trivial subsystems.

[Thomas Naughton]

Bernard,

I didn't look at the rdiff tool but the old RCS software is pretty basic
and does incremental diffs and has logs from what I remember.

Also, I have a very vague memory of Brian Finley saying that someone had
used CVS or some other revision ctrl system with SystemImager images.
Maybe it was more of a hack than anything formal???

later,
--tjn

_________________________________________________________________________
Thomas Naughton ***@ornl.gov
Research Associate [phone]

Post by Bernard Li
This is a great idea! I think we can definitely build upon this tool.
I would like to keep revision notes, and I do not see this capability
with rdiff-backup, perhaps we can implement a sqlite backend (or a
text file...?) to keep revision logs.
si_rci st: rdiff-backup --compare <image> <backup>
si_rci log: rdiff-backup --list-increments <backup>
si_rci ci: rdiff-backup <image> <backup>
si_rci revert: rdiff-backup --restore <image> <backup>
si_rci restore 1: rdiff-backup --force --restore-as-of 1B <backup> <image>
...
(Here, rci stands for Revision Control for Image :-) )
I would also like to tie this in with a si_chroot wrapper, which
si_chroot <image_name>
and would wrap chroot. It will also ensure that once you exit from
the chroot, your modifications are automatically checked in.
I tested this on Fedora Core 6 VMWare on a 1GB image, the operations
did not take too long. This really looks promising. I will try to do
some tests tomorrow with real hardware...
Sounds like an IRC brainstorming session is in order ;-)
Cheers,
Bernard

Post by Andrea Righi

Post by Bernard Li
Does anybody have a suggestion on a revision control system for
SystemImager images (chroot)?
Does anybody even want such a feature?
I am thinking along the lines of recording what files have been
changed when and being able to roll back to previous revisions etc.
You could keep entire backups of your entire image, but that eats up a
lot of space quickly if your image is big.
SVN seems like an overkill, since you probably just want the revision
control bits to be local to the system (included in the image), plus
it probably cannot handle file ownership correctly (not to mention
treat special files in /dev).
RCS may be a good way to implement this. Also some sort of
LVM/snapshot mechanism can be used.
Any thoughts on this topic?
Cheers,
Bernard

Bernard,
have you seen this?
http://www.nongnu.org/rdiff-backup/index.html
We could implement a versioning mechanism using this tool, maybe saving
incremental changes in /var/lib/systemimager/backups or similar... since
it supports also remote server backups the user could choose also to
push backups to an external machine to have a mirror image server, or
similar stuff...
Moreover the package seems to be already included in SuSE, Fedora,
Debian, etc...
See also this howto: http://www.howtoforge.com/linux_rdiff_backup
Cheers,
-Andrea

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