[RFC] Moving from Bazaar (bzr) to git

[RFC] Moving from Bazaar (bzr) to git

[Paul Menzel]

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Dear GRUB folks,


this is *not* the start of a flame war about what VCS is the best.

Hopefully everyone will agree, that git is the most popular one in the
FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
are now familiar with the basic git commands. So using Bazaar is one
more thing to deal with for new contributors before making a
contribution to GRUB. (I know there is git-bzr-ng, but it is still one
more step.)

Talking to Vladimir and Colin in #grub, they did not oppose a migration
to git and Vladimir asked me to bring it up on the list.

Does anyone have experience with such a move and how to do it on
Savannah? Could you please share these? That would be great.


Thanks,

Paul

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Re: [RFC] Moving from Bazaar (bzr) to git

[Keshav Padram]

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On 22 June 2013 23:30, Paul Menzel <paulepanter@users.sourceforge.net>wrote:

> Dear GRUB folks,
>
>
> this is *not* the start of a flame war about what VCS is the best.
>
> Hopefully everyone will agree, that git is the most popular one in the
> FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
> are now familiar with the basic git commands. So using Bazaar is one
> more thing to deal with for new contributors before making a
> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
> more step.)
>
> Talking to Vladimir and Colin in #grub, they did not oppose a migration
> to git and Vladimir asked me to bring it up on the list.
>
> Does anyone have experience with such a move and how to do it on
> Savannah? Could you please share these? That would be great.
>
>
I don't have an idea how to do it in Savannah. But you can also use
git-remote-bzr (
http://felipec.wordpress.com/2012/11/13/git-remote-hg-bzr-2/ ) apart from
git-bzr-ng to checkout bzr repo via git. git-remote-bzr is part of git
contrib scripts and is already shipped as part of git pkg in many distros
(/usr/share/git/remote-helpers/git-remote-bzr in Arch Linux). I currently
use grub bzr via git-remote-bzr.


> Thanks,
>
> Paul
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>
>

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Re: [RFC] Moving from Bazaar (bzr) to git

[Andrey Borzenkov]

В Sun, 23 Jun 2013 00:09:31 +0530
Keshav Padram <the.ridikulus.rat@gmail.com> пишет:

> On 22 June 2013 23:30, Paul Menzel <paulepanter@users.sourceforge.net>wrote:
> 
> > Dear GRUB folks,
> >
> >
> > this is *not* the start of a flame war about what VCS is the best.
> >
> > Hopefully everyone will agree, that git is the most popular one in the
> > FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
> > are now familiar with the basic git commands. So using Bazaar is one
> > more thing to deal with for new contributors before making a
> > contribution to GRUB. (I know there is git-bzr-ng, but it is still one
> > more step.)
> >
> > Talking to Vladimir and Colin in #grub, they did not oppose a migration
> > to git and Vladimir asked me to bring it up on the list.
> >
> > Does anyone have experience with such a move and how to do it on
> > Savannah? Could you please share these? That would be great.
> >
> >
> I don't have an idea how to do it in Savannah. But you can also use
> git-remote-bzr (
> http://felipec.wordpress.com/2012/11/13/git-remote-hg-bzr-2/ ) apart from
> git-bzr-ng to checkout bzr repo via git. git-remote-bzr is part of git
> contrib scripts and is already shipped as part of git pkg in many distros
> (/usr/share/git/remote-helpers/git-remote-bzr in Arch Linux). I currently
> use grub bzr via git-remote-bzr.
> 

git-remote-bzr (and git-bzr-ng) are good to keep track of single
branch, but they won't replicate existing branches structure of bzr
repo. That will probably be the main problem. bzr and git use
sufficiently different work flow, so this will likely need to be done
manually (scripting).

git-remote-bzr does replicated all commits and stores branch tips,
which provides enough information to recreate branches in git. OTOH
with git often is using repo clones (which are really easy and cheap)
for what bzr is using branches. At least people/* branches are good
candidates for becoming separate repositories. 

I also do not know to which extent merge information is compatible
between git and bzr and whether this will preserve merge history,
assuming this is important.

Re: [RFC] Moving from Bazaar (bzr) to git

[Bruce Dubbs]

Paul Menzel wrote:
> Dear GRUB folks,
>
>
> this is *not* the start of a flame war about what VCS is the best.
>
> Hopefully everyone will agree, that git is the most popular one in the
> FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
> are now familiar with the basic git commands. So using Bazaar is one
> more thing to deal with for new contributors before making a
> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
> more step.)
>
> Talking to Vladimir and Colin in #grub, they did not oppose a migration
> to git and Vladimir asked me to bring it up on the list.

Personally, I prefer subversion, but I'm not a GRUB developer.  The 
choice of version control can be similar emacs/vi or Bourne Shell/C 
Shell, so it really should be the choice of the primary developers.

Using Google for 'git vs subversion' provides a lot of interesting 
opinions.

   -- Bruce

Re: [RFC] Moving from Bazaar (bzr) to git

[Mikko Rantalainen]

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Bruce Dubbs, 2013-06-23 00:52 (Europe/Helsinki):
> Paul Menzel wrote:
>> this is *not* the start of a flame war about what VCS is the best.
>>
>> Hopefully everyone will agree, that git is the most popular one in the
>> FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
>> are now familiar with the basic git commands. So using Bazaar is one
>> more thing to deal with for new contributors before making a
>> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
>> more step.)
> 
> Personally, I prefer subversion, but I'm not a GRUB developer.  The
> choice of version control can be similar emacs/vi or Bourne Shell/C
> Shell, so it really should be the choice of the primary developers.

I disagree. The choice of version control means a lot more than working
environment of a single developer (primary developer or not) because
that is the medium for sharing the source code. Even Linus himself uses
git over patches from email, even though the latter method is not bad
either for a single patch.

Once you master even a single DVCS system (e.g. Git, Mercurial, Bazaar),
the limitations caused by subversion or any other centralized version
control system start to look much greater than before.

I'd suggest trying to apply the workflow used by git development for
grub, too.

Make sure to have a mirror at github.com and if you don't want to use
github's issue tracker, put a big disclaimer about that in github. As
far as I know, you cannot disable public issue tracker in github
repository's settings.

-- 
Mikko



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Re: [RFC] Moving from Bazaar (bzr) to git

[Daniel Kahn Gillmor]

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On 06/24/2013 06:27 AM, Mikko Rantalainen wrote:
> I'd suggest trying to apply the workflow used by git development for
> grub, too.

While i don't expect my opinion to have any particular weight (i'm
mostly a bug reporter and tester in this community) i would also be
happy to see a switch from bzr to git if the upstream devs are OK with it.

> Make sure to have a mirror at github.com and if you don't want to use
> github's issue tracker, put a big disclaimer about that in github. As
> far as I know, you cannot disable public issue tracker in github
> repository's settings.

I have to disagree with the above.  Maintaining a mirror at github.com
is not at all a requirement, and the maintenance of such a mirror is
extra work (however small).  The extra mirror can potentially create
confusion if it isn't properly maintained, as can the github issue
tracker if it isn't the canonical issue tracker.  If you consider
switching to git, please don't spend any extra cycles worrying about
github.com integration unless you have a compelling reason to do so.

	--dkg


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Re: [RFC] Moving from Bazaar (bzr) to git

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 24.06.2013 12:27, Mikko Rantalainen wrote:
> Bruce Dubbs, 2013-06-23 00:52 (Europe/Helsinki):
>> Paul Menzel wrote:
>>> this is *not* the start of a flame war about what VCS is the best.
>>>
>>> Hopefully everyone will agree, that git is the most popular one in the
>>> FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
>>> are now familiar with the basic git commands. So using Bazaar is one
>>> more thing to deal with for new contributors before making a
>>> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
>>> more step.)
>>
>> Personally, I prefer subversion, but I'm not a GRUB developer.  The
>> choice of version control can be similar emacs/vi or Bourne Shell/C
>> Shell, so it really should be the choice of the primary developers.
>
> I disagree. The choice of version control means a lot more than working
> environment of a single developer (primary developer or not) because
> that is the medium for sharing the source code. Even Linus himself uses
> git over patches from email, even though the latter method is not bad
> either for a single patch.
>
> Once you master even a single DVCS system (e.g. Git, Mercurial, Bazaar),
> the limitations caused by subversion or any other centralized version
> control system start to look much greater than before.
>
> I'd suggest trying to apply the workflow used by git development for
> grub, too.
>
> Make sure to have a mirror at github.com and if you don't want to use
> github's issue tracker, put a big disclaimer about that in github. As
> far as I know, you cannot disable public issue tracker in github
> repository's settings.
>
Moving away from savannah is out of the question. Savannah is official 
place for GNU projects and as such we'll stay at savannah.

Re: [RFC] Moving from Bazaar (bzr) to git

[Gregg Levine]

On Mon, Jun 24, 2013 at 10:54 PM, Vladimir 'φ-coder/phcoder'
Serbinenko <phcoder@gmail.com> wrote:
> On 24.06.2013 12:27, Mikko Rantalainen wrote:
>>
>> Bruce Dubbs, 2013-06-23 00:52 (Europe/Helsinki):
>>>
>>> Paul Menzel wrote:
>>>>
>>>> this is *not* the start of a flame war about what VCS is the best.
>>>>
>>>> Hopefully everyone will agree, that git is the most popular one in the
>>>> FOSS world (Linux, freedesktop.org, GNOME, KDE, ...) and a lot of people
>>>> are now familiar with the basic git commands. So using Bazaar is one
>>>> more thing to deal with for new contributors before making a
>>>> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
>>>> more step.)
>>>
>>>
>>> Personally, I prefer subversion, but I'm not a GRUB developer.  The
>>> choice of version control can be similar emacs/vi or Bourne Shell/C
>>> Shell, so it really should be the choice of the primary developers.
>>
>>
>> I disagree. The choice of version control means a lot more than working
>> environment of a single developer (primary developer or not) because
>> that is the medium for sharing the source code. Even Linus himself uses
>> git over patches from email, even though the latter method is not bad
>> either for a single patch.
>>
>> Once you master even a single DVCS system (e.g. Git, Mercurial, Bazaar),
>> the limitations caused by subversion or any other centralized version
>> control system start to look much greater than before.
>>
>> I'd suggest trying to apply the workflow used by git development for
>> grub, too.
>>
>> Make sure to have a mirror at github.com and if you don't want to use
>> github's issue tracker, put a big disclaimer about that in github. As
>> far as I know, you cannot disable public issue tracker in github
>> repository's settings.
>>
> Moving away from savannah is out of the question. Savannah is official place
> for GNU projects and as such we'll stay at savannah.
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel

Hello!
I agree. Moving away from hosting there is not an option. But what
about the decision concerning BZR?

-----
Gregg C Levine gregg.drwho8@gmail.com
"This signature fought the Time Wars, time and again."

Re: [RFC] Moving from Bazaar (bzr) to git

[Lennart Sorensen]

On Sat, Jun 22, 2013 at 04:52:04PM -0500, Bruce Dubbs wrote:
> Personally, I prefer subversion, but I'm not a GRUB developer.  The
> choice of version control can be similar emacs/vi or Bourne Shell/C
> Shell, so it really should be the choice of the primary developers.
> 
> Using Google for 'git vs subversion' provides a lot of interesting
> opinions.

I find subversion almost as annoying as bazaar to deal with.  It makes
it very hard to find what you want to find.  Like bazaar, the only way
to tolerate subversion is to use a convertor to git format.

-- 
Len Sorensen

Re: [RFC] Moving from Bazaar (bzr) to git

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 24.06.2013 16:09, Lennart Sorensen wrote:
> On Sat, Jun 22, 2013 at 04:52:04PM -0500, Bruce Dubbs wrote:
>> Personally, I prefer subversion, but I'm not a GRUB developer.  The
>> choice of version control can be similar emacs/vi or Bourne Shell/C
>> Shell, so it really should be the choice of the primary developers.
>>
>> Using Google for 'git vs subversion' provides a lot of interesting
>> opinions.
>
> I find subversion almost as annoying as bazaar to deal with.  It makes
> it very hard to find what you want to find.  Like bazaar, the only way
> to tolerate subversion is to use a convertor to git format.

No flame-war messages please. You can voice your support pro or contra 
based on convenience for you but please don't transform this into flame war.

Re: [RFC] Moving from Bazaar (bzr) to git

[Lennart Sorensen]

On Tue, Jun 25, 2013 at 04:57:25AM +0200, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> No flame-war messages please. You can voice your support pro or
> contra based on convenience for you but please don't transform this
> into flame war.

I didn't intend to.  I was only trying to say I find the interface for
both hard to work with.

I should have phrased it better.

I know some people find git weird.  I suppose it depends what you are
used to.  I sure am happy there exists translations between many of the
systems so you can work with something you like locally.

-- 
Len Sorensen

Re: [RFC] Moving from Bazaar (bzr) to git

[Geoffrey Thomas]

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On Sat, 22 Jun 2013, Paul Menzel wrote:

> Hopefully everyone will agree, that git is the most popular one in the
> FOSS world (Linux, freedesktop.org, GNOME, KDE, …) and a lot of people
> are now familiar with the basic git commands. So using Bazaar is one
> more thing to deal with for new contributors before making a
> contribution to GRUB. (I know there is git-bzr-ng, but it is still one
> more step.)
>
> Talking to Vladimir and Colin in #grub, they did not oppose a migration
> to git and Vladimir asked me to bring it up on the list.
>
> Does anyone have experience with such a move and how to do it on
> Savannah? Could you please share these? That would be great.

I did a conversion via bzr fast-export | git fast-import a while ago for 
my workplace, so that we could internally use git for development (so we 
all don't have to learn yet another VCS). Our priorities have shifted so 
we haven't hacked on GRUB for a while, but this thread inspired me to dust 
off the conversion, and re-attempt setting up a cronjob to do the import. 
I believe I now have it working and it should push new commits every hour:

   https://github.com/mokafive/grub

I'd be thrilled for GRUB to adopt that history -- let me know if it looks 
reasonable. Until there's a move to git, I intend to keep the URL working, 
so feel free to clone and format-patch from there. I'll try not to break 
history, but if someone points out that something got mis-imported, I'll 
fix that, which will involve rewriting history.

I haven't handled branches, because they don't look very active and 
honestly I don't yet understand bzr branching. I think handling it is 
straightforward, though, so I will figure that out if someone asks.

If you're curious about the details, the scripts I used for the conversion 
are at the end of the email; consider them freely usable with no 
restrictions. Here are the issues I ran into:

* For some reason, git packs the fast-import very, very poorly, causing 
the .git directory to balloon to over a gigabyte (for comparison, the .bzr 
directory is 21M). Running `git gc --aggressive` fixes it and drops .git 
to more like 20M. Note that Github seems to preserve the packing you send 
it, so if you make a new repo on the Github web interface, clones _from_ 
there will be gargantuan if you don't run the aggressive GC before the 
first time you push. I don't seem to need to rerun the GC on incremental 
imports, fortunately.

* A couple of commits (like 
cjwatson@ubuntu.com-20110330103133-rwadssw622rhkogw / b38045f in my 
import) seem to have an empty author name or email, when fast-exported, 
but a valid committer. So I set the author to the committer.

* .bzrignore needs to become .gitignore, so I changed that in each commit 
so that checking out older commits works reasonably. bzr has some built-in 
defaults that git doesn't, that GRUB makes use of (like *.o), so I added 
those. Also, .bzrignore itself was listed in .bzrignore, which strikes me 
as odd.

* I couldn't easily figure out how to make filter-branch resume from a 
certain point. Fortunately it doesn't take _that_ long to filter the whole 
thing, and is consistent. I think you can do this with .git/info/replace, 
if you really care, though.

There's nothing Github-specific about the import, so it should upload to 
Savannah just fine. I can post the "marks" files, for converting between 
bzr and git commit names, if people find them useful.

As probably implied by the fact that I did this, I'm a fan of moving, both 
because git is significantly more popular and because I find the UI better 
than bzr's (although that may just be familiarity).

-- 
Geoffrey Thomas
gthomas@mokafive.com

[gthomas@hobgoblin grub]$ crontab -l
0 * * * * chronic /home/gthomas/src/grub/import.sh
[gthomas@hobgoblin grub]$ cat import.sh
#!/bin/sh

set -e

cd ~/src/grub/bzr
bzr up
cd ~/src/grub/git
bzr fast-export --branch=import --marks=../bzr-marks ../bzr | git fast-import --import-marks-if-exists=../git-marks --export-marks=../git-marks --quiet
git reset --hard
../filter.sh
git reset --hard
git push github HEAD:upstream
[gthomas@hobgoblin grub]$ cat filter.sh
#!/bin/sh

set -e

export default_ignores=$(python -c "from bzrlib import ignores; print \"\\n\".join(ignores.USER_DEFAULTS)")

git update-ref -m "New upstream" refs/heads/upstream import
git checkout upstream
git reset --hard

dir=$(mktemp -d --tmpdir=${XDG_RUNTIME_DIR:-/tmp} filter-branch.XXXXXX)
git filter-branch -f -d "$dir" --env-filter '
     export GIT_AUTHOR_NAME=${GIT_AUTHOR_NAME:-$GIT_COMMITTER_NAME}
     export GIT_AUTHOR_EMAIL=${GIT_AUTHOR_EMAIL:-$GIT_COMMITTER_EMAIL}
    ' --index-filter '
     flag=0
     if git checkout .bzrignore 2>/dev/null; then
         sed "s/^\*\*\///" .bzrignore | grep -v .bzrignore > .gitignore
         echo "$default_ignores" >> .gitignore
         git rm -qf .bzrignore
         git diff .gitignore
         git add .gitignore
         if git show --pretty=format: --name-only "$GIT_COMMIT" | grep -Fxq .bzrignore; then
             flag=1
         fi
     fi' --msg-filter '
     cat
     if [ "$flag" = 1 ]; then
         echo
         echo "[git importer: converted .bzrignore to .gitignore]"
     fi'

Re: [RFC] Moving from Bazaar (bzr) to git

[Darik Horn]

On Mon, Jun 24, 2013 at 9:50 PM, Geoffrey Thomas <gthomas@mokafive.com> wrote:
>
> * A couple of commits (like
> cjwatson@ubuntu.com-20110330103133-rwadssw622rhkogw / b38045f in my import)
> seem to have an empty author name or email, when fast-exported, but a valid
> committer. So I set the author to the committer.

The latest git import helper correctly handles all of these bzr
records.  If you put this file in /usr/local/bin, then you can move
the entire GRUB history from bzr to git without any manual edits:

https://github.com/felipec/git/blob/fc/master/contrib/remote-helpers/git-remote-bzr.py

-- 
Darik Horn <dajhorn@vanadac.com>

Re: [RFC] Moving from Bazaar (bzr) to git

[Geoffrey Thomas]

On Tue, 25 Jun 2013, Darik Horn wrote:

> On Mon, Jun 24, 2013 at 9:50 PM, Geoffrey Thomas <gthomas@mokafive.com> wrote:
>>
>> * A couple of commits (like
>> cjwatson@ubuntu.com-20110330103133-rwadssw622rhkogw / b38045f in my import)
>> seem to have an empty author name or email, when fast-exported, but a valid
>> committer. So I set the author to the committer.
>
> The latest git import helper correctly handles all of these bzr
> records.  If you put this file in /usr/local/bin, then you can move
> the entire GRUB history from bzr to git without any manual edits:
>
> https://github.com/felipec/git/blob/fc/master/contrib/remote-helpers/git-remote-bzr.py

Ah, thanks. I'm using bzr-fast-export, not git-remote-bzr, but that might 
be worth a shot. Theoretically they should export the same tree, I guess 
-- it looks like they're using the same solution.

Looks like git-remote-bzr doesn't handle the .bzrignore -> .gitignore 
munging that I included, so we would still need to fix those up, if we 
wanted ignores to work right when checking out an old commit (which I 
think is desirable).

-- 
Geoffrey Thomas
gthomas@mokafive.com