SVN migration

SVN migration

[William Hall]

Hi gitters,

Background - I'm trying to convince my company to ditch SVN for git - 
the usual story. So for the duration of a project I'll be running git 
and SVN in parallel - the idea being is that we will still commit to SVN 
(and update), but the development work internal to my team will be using 
git.

An absolute *must* is for the SVN repo to continue as the SCM authority 
- at least until I can persuade the company to switch to git permanently.

Here's some crap ascii art to show the situation,

--------------
| non-git dev |
--------------
      |
      |
   -------         ----------------
  |  SVN  |-------| git/SVN bridge |
   -------         ----------------
                         |
                   ---------------
                  | bare git Repo |
                   ---------------
                         |
          ------------------------------
          |              |              |
        dev_1          dev_2          dev 3


- the git/SVN bridge is a git repo created with git-svn-clone.

- the 'bare git' repo is a typical standard git repo and I'm keen for 
the developers to experience a 'normal' git environment and not have to 
worry about SVN interactions.

Am sure this problem has been considered many times before, but I cannot 
seem to find an effective solution.

The issue is the dcommit operation from the bridge. The rebase part of 
this re-writes the commit messages to include the SVN commit-ids which 
is nice, but screws up the push/pulls between the bridge and the bare repo.

One solution I've tried is to create a branch in the bridge that tracks 
the bare repo, and another branch to track the SVN server. If the 
branches are kept separate then I can git-cherry-pick to replay changes 
from one side to the other (or at least merge one-way). his is not ideal 
as I really should use git's merge facility. I'd like to guarantee that 
the sides are not diverging over time.

Actually I've tried all permutations of merges/rebases/update-ref, I 
always fall into the same trap that befits a rebase in conjunction with 
remote repositories.

I can live without tags and branches for the time being - I just want to 
get a robust workflow defined in the bridge for the SVN 'trunk' - ie 
read/writes in both directions.

If anyone can offer any advice then it would be hugely appreciated. 
Perhaps you'll say that it cannot be done, which would make the git sell 
much harder.

Hopefully by the end of this exercise git will have 800 more fans.

Many thanks

Will

Re: SVN migration

[Steven Michalske]

On Jun 16, 2010, at 4:02 PM, William Hall wrote:

> 
> The issue is the dcommit operation from the bridge. The rebase part of this re-writes the commit messages to include the SVN commit-ids which is nice, but screws up the push/pulls between the bridge and the bare repo.

Look into svn.noMetadata configuration option.  It will prevent you from rebuilding the svn to git bridge if something seriously goes wrong, but it prevents the messages from changing.

svn-remote.<name>.noMetadata
This gets rid of the git-svn-id: lines at the end of every commit.
If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able to rebuild it and you won't be able to fetch again, either. This is fine for one-shot imports.
The git svn log command will not work on repositories using this, either. Using this conflicts with the useSvmProps option for (hopefully) obvious reasons

Re: SVN migration

[William Hall]

Thanks Steven,

The noMetadata option will prevent me from doing anything other than a 
one-shot import, which is not what I want. I need to somehow devise a 
workflow that allows me bidirectional push/pull between an svn repo and 
a remote git repo.



Steven Michalske wrote:
> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
> 
>> The issue is the dcommit operation from the bridge. The rebase part of this re-writes the commit messages to include the SVN commit-ids which is nice, but screws up the push/pulls between the bridge and the bare repo.
> 
> Look into svn.noMetadata configuration option.  It will prevent you from rebuilding the svn to git bridge if something seriously goes wrong, but it prevents the messages from changing.
> 
> svn-remote.<name>.noMetadata
> This gets rid of the git-svn-id: lines at the end of every commit.
> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able to rebuild it and you won't be able to fetch again, either. This is fine for one-shot imports.
> The git svn log command will not work on repositories using this, either. Using this conflicts with the useSvmProps option for (hopefully) obvious reasons

Re: SVN migration

[William Hall]

I'm going to answer my own post, I *think* I have something that works - 
please check if I'm doing anything idiotic.

Just to recap: trying to convince my company to move from svn to git, 
and they have agreed to try one project using git as long as all commits 
find their way to the svn repo as well.

So I have a standard bare git repo serving the developers, a git/svn 
"bridge" repo that performs bi-directional updates to and from svn and 
the bare git repo.

Ok, here's what I've done

Create bridge
-------------
$ git svn init -s file:///path_to_svn /path_to_git_svn_bridge/
$ cd /path_to_git_svn_bridge
$ git svn fetch --authors-file=/tmp/authors.map

Configure bare repo
-------------------------------
create bare repo that developers will use
$ git init --shared=all --bare /path_to_git_repo.git

configure bridge
----------------
$ git remote add -f -m master origin /path_to_git_repo.git
$ git push origin master
$ git branch --set-upstream master origin/master

this branch will be used to perform svn rebases and fetches
$ git checkout -t -b svn svn/trunk


Workflow
--------
Developer A clones from /path_to_git_repo.git, does some work, commits 
and pushes back to origin

Now, in the bridge repo, fetch changes from origin (where developer A 
pushed)
$ git checkout master
$ git pull

Replay all changes manually, in order, onto svn branch
$ git checkout svn
$ git rev-list --reverse heads/master@{1}..heads/master | while read rev; do
         git cherry-pick -n $rev
   done

Create one commit for all changes and synchronise with svn
$ git commit -am "cherry pick merge"
$ git svn rebase
$ git svn dcommit

Now merge in anything picked up from svn, plus the rebased final commit
$ git checkout master
$ git merge svn

Send back to bare repo (at least the final merge commit)
$ git push

It seems to handle changes and preserves linear history on both sides ok.
Can anyone see anything obviously wrong with this approach?

thanks,

Will






William Hall wrote:
 > Thanks Steven,
 >
 > The noMetadata option will prevent me from doing anything other than 
a one-shot import, which is not what I want. I need to somehow devise a 
workflow that allows me bidirectional push/pull between an svn repo and 
a remote git repo.
 >
 >
 >
 > Steven Michalske wrote:
 >> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
 >>
 >>> The issue is the dcommit operation from the bridge. The rebase part 
of this re-writes the commit messages to include the SVN commit-ids 
which is nice, but screws up the push/pulls between the bridge and the 
bare repo.
 >>
 >> Look into svn.noMetadata configuration option.  It will prevent you 
from rebuilding the svn to git bridge if something seriously goes wrong, 
but it prevents the messages from changing.
 >>
 >> svn-remote.<name>.noMetadata
 >> This gets rid of the git-svn-id: lines at the end of every commit.
 >> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be 
able to rebuild it and you won't be able to fetch again, either. This is 
fine for one-shot imports.
 >> The git svn log command will not work on repositories using this, 
either. Using this conflicts with the useSvmProps option for (hopefully) 
obvious reasons
 > --
 > To unsubscribe from this list: send the line "unsubscribe git" in
 > the body of a message to majordomo@vger.kernel.org
 > More majordomo info at  http://vger.kernel.org/majordomo-info.html


William Hall wrote:
> Thanks Steven,
> 
> The noMetadata option will prevent me from doing anything other than a 
> one-shot import, which is not what I want. I need to somehow devise a 
> workflow that allows me bidirectional push/pull between an svn repo and 
> a remote git repo.
> 
> 
> 
> Steven Michalske wrote:
>> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
>>
>>> The issue is the dcommit operation from the bridge. The rebase part 
>>> of this re-writes the commit messages to include the SVN commit-ids 
>>> which is nice, but screws up the push/pulls between the bridge and 
>>> the bare repo.
>>
>> Look into svn.noMetadata configuration option.  It will prevent you 
>> from rebuilding the svn to git bridge if something seriously goes 
>> wrong, but it prevents the messages from changing.
>>
>> svn-remote.<name>.noMetadata
>> This gets rid of the git-svn-id: lines at the end of every commit.
>> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be 
>> able to rebuild it and you won't be able to fetch again, either. This 
>> is fine for one-shot imports.
>> The git svn log command will not work on repositories using this, 
>> either. Using this conflicts with the useSvmProps option for 
>> (hopefully) obvious reasons
> -- 
> To unsubscribe from this list: send the line "unsubscribe git" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: SVN migration

[Joshua Shrader]

In Jon Loeliger's "Version Control with Git", Chapter 16, he describes
a similar situation in which there is a Subversion repository, and at
least a couple users that want to be using Git.  He proposes a single
"gatekeeper" git repository, what you refer to as a bridge, which is
the only interface to subversion.  After git svn cloneing the
subversion repo (with --prefix=svn/), all the branches are then pushed
to a bare repository (git push ../svn-bare.git
'refs/remotes/svn/*:refs/heads/svn/*', and other git users are told to
clone this repo, which now contains local branches of all the svn
remotes.  Then, to merge back to subversion, in the gatekeeper repo,
you do

git checkout svn/trunk (or other branch - this is checking out a
detached head as svn/trunk is a remote)
git merge --no-ff new-feature
git svn dcommit

This results in a merge commit on a detached head, and then the
modified commit (after the git-svn-id line is added) is put on the
real svn/trunk branch.  The commit on the detached head is "worse than
redundant.  Using it for anything else eventually results in
conflicts.  So, just forget about that commit.  If you haven't put it
on a branch in the first place, it's that much easier to forget" (Jon
Loeliger).

I haven't tried this yet, but I'm in a similar situation in that I'm
trying to convince my project to convert to using Git.  We're going to
use this gatekeeper approach for a while, and allow users to migrate
over at their own discretion.  Then hopefully, if there's not too much
resistance, we'll get rid of the subversion repo entirely.

If there's a problem with this workflow, I'd love to hear about it.
I'm only in the middle of setting this up, but hopefully I should know
if it works by the end of the week.

On Thu, Jun 17, 2010 at 12:27 PM, William Hall <will@gnatter.net> wrote:
> I'm going to answer my own post, I *think* I have something that works -
> please check if I'm doing anything idiotic.
>
> Just to recap: trying to convince my company to move from svn to git, and
> they have agreed to try one project using git as long as all commits find
> their way to the svn repo as well.
>
> So I have a standard bare git repo serving the developers, a git/svn
> "bridge" repo that performs bi-directional updates to and from svn and the
> bare git repo.
>
> Ok, here's what I've done
>
> Create bridge
> -------------
> $ git svn init -s file:///path_to_svn /path_to_git_svn_bridge/
> $ cd /path_to_git_svn_bridge
> $ git svn fetch --authors-file=/tmp/authors.map
>
> Configure bare repo
> -------------------------------
> create bare repo that developers will use
> $ git init --shared=all --bare /path_to_git_repo.git
>
> configure bridge
> ----------------
> $ git remote add -f -m master origin /path_to_git_repo.git
> $ git push origin master
> $ git branch --set-upstream master origin/master
>
> this branch will be used to perform svn rebases and fetches
> $ git checkout -t -b svn svn/trunk
>
>
> Workflow
> --------
> Developer A clones from /path_to_git_repo.git, does some work, commits and
> pushes back to origin
>
> Now, in the bridge repo, fetch changes from origin (where developer A
> pushed)
> $ git checkout master
> $ git pull
>
> Replay all changes manually, in order, onto svn branch
> $ git checkout svn
> $ git rev-list --reverse heads/master@{1}..heads/master | while read rev; do
>        git cherry-pick -n $rev
>  done
>
> Create one commit for all changes and synchronise with svn
> $ git commit -am "cherry pick merge"
> $ git svn rebase
> $ git svn dcommit
>
> Now merge in anything picked up from svn, plus the rebased final commit
> $ git checkout master
> $ git merge svn
>
> Send back to bare repo (at least the final merge commit)
> $ git push
>
> It seems to handle changes and preserves linear history on both sides ok.
> Can anyone see anything obviously wrong with this approach?
>
> thanks,
>
> Will
>
>
>
>
>
>
> William Hall wrote:
>> Thanks Steven,
>>
>> The noMetadata option will prevent me from doing anything other than a
>> one-shot import, which is not what I want. I need to somehow devise a
>> workflow that allows me bidirectional push/pull between an svn repo and a
>> remote git repo.
>>
>>
>>
>> Steven Michalske wrote:
>>> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
>>>
>>>> The issue is the dcommit operation from the bridge. The rebase part of
>>>> this re-writes the commit messages to include the SVN commit-ids which is
>>>> nice, but screws up the push/pulls between the bridge and the bare repo.
>>>
>>> Look into svn.noMetadata configuration option.  It will prevent you from
>>> rebuilding the svn to git bridge if something seriously goes wrong, but it
>>> prevents the messages from changing.
>>>
>>> svn-remote.<name>.noMetadata
>>> This gets rid of the git-svn-id: lines at the end of every commit.
>>> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able
>>> to rebuild it and you won't be able to fetch again, either. This is fine for
>>> one-shot imports.
>>> The git svn log command will not work on repositories using this, either.
>>> Using this conflicts with the useSvmProps option for (hopefully) obvious
>>> reasons
>> --
>> To unsubscribe from this list: send the line "unsubscribe git" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
> William Hall wrote:
>>
>> Thanks Steven,
>>
>> The noMetadata option will prevent me from doing anything other than a
>> one-shot import, which is not what I want. I need to somehow devise a
>> workflow that allows me bidirectional push/pull between an svn repo and a
>> remote git repo.
>>
>>
>>
>> Steven Michalske wrote:
>>>
>>> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
>>>
>>>> The issue is the dcommit operation from the bridge. The rebase part of
>>>> this re-writes the commit messages to include the SVN commit-ids which is
>>>> nice, but screws up the push/pulls between the bridge and the bare repo.
>>>
>>> Look into svn.noMetadata configuration option.  It will prevent you from
>>> rebuilding the svn to git bridge if something seriously goes wrong, but it
>>> prevents the messages from changing.
>>>
>>> svn-remote.<name>.noMetadata
>>> This gets rid of the git-svn-id: lines at the end of every commit.
>>> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able
>>> to rebuild it and you won't be able to fetch again, either. This is fine for
>>> one-shot imports.
>>> The git svn log command will not work on repositories using this, either.
>>> Using this conflicts with the useSvmProps option for (hopefully) obvious
>>> reasons
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe git" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
> --
> To unsubscribe from this list: send the line "unsubscribe git" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: SVN migration

[William Hall]

Hi Joshua - glad I'm not the only one facing this conundrum.

Yes, I've followed the Jon Loeliger's guide and am using something very 
similar.

I've come up with a couple of solutions, but this is my latest effort.
The only real difference in our situations is that I wanted the 
developers to get a feel of a bog-standard bare git repo to which they 
pull/push as usual - the gateway (...much better name) will also push 
and pull to this.

I've created a post-update hook in the bare git repo that does the 
following on the gateway repo

( there's a branch "svn" that tracks refs/remotes/svn/trunk)
- pulls commits from bare repo into master (all current dev work)
- on svn branch, run "git merge --squash master"
- commit changes
- git svn rebase (pick up changes from other depts)
- git svn dcommit
- switch back to master and merge in svn changes (with --no-ff)
- git push, back to bare repo

All git commits between pushes are squashed which probably represents 
the frequency of usual svn commits (ie, only when something is finished) 
so it's probably ok. Also, it prevents the developers from seeing 
duplicate commit messages - one from master and a duplicate (with svn 
commit-id) which may get annoying or confusing.

I've also tried doing a rebase with --onto to replay all changes to 
master onto the svn branch, which is ok, but all commits are duplicated 
and propagated.

I'm keen to merge the branches at some stage otherwise I'll end up with 
two branches on the gateway that never converge - which is probably not 
a good idea.

Have tried (briefly) your solution which also seems to work, but without 
any merge commits - will try more.

Naturally, I'd like a completely linear history, but the does not seem 
viable. I don't think git will be hard sell (most of our developers seem 
to agree that git is the future), but I need to get this right from the 
outset or confidence will be lost.


will




On 21/06/10 22:12, Joshua Shrader wrote:
> In Jon Loeliger's "Version Control with Git", Chapter 16, he describes
> a similar situation in which there is a Subversion repository, and at
> least a couple users that want to be using Git.  He proposes a single
> "gatekeeper" git repository, what you refer to as a bridge, which is
> the only interface to subversion.  After git svn cloneing the
> subversion repo (with --prefix=svn/), all the branches are then pushed
> to a bare repository (git push ../svn-bare.git
> 'refs/remotes/svn/*:refs/heads/svn/*', and other git users are told to
> clone this repo, which now contains local branches of all the svn
> remotes.  Then, to merge back to subversion, in the gatekeeper repo,
> you do
>
> git checkout svn/trunk (or other branch - this is checking out a
> detached head as svn/trunk is a remote)
> git merge --no-ff new-feature
> git svn dcommit
>
> This results in a merge commit on a detached head, and then the
> modified commit (after the git-svn-id line is added) is put on the
> real svn/trunk branch.  The commit on the detached head is "worse than
> redundant.  Using it for anything else eventually results in
> conflicts.  So, just forget about that commit.  If you haven't put it
> on a branch in the first place, it's that much easier to forget" (Jon
> Loeliger).
>
> I haven't tried this yet, but I'm in a similar situation in that I'm
> trying to convince my project to convert to using Git.  We're going to
> use this gatekeeper approach for a while, and allow users to migrate
> over at their own discretion.  Then hopefully, if there's not too much
> resistance, we'll get rid of the subversion repo entirely.
>
> If there's a problem with this workflow, I'd love to hear about it.
> I'm only in the middle of setting this up, but hopefully I should know
> if it works by the end of the week.
>
> On Thu, Jun 17, 2010 at 12:27 PM, William Hall<will@gnatter.net>  wrote:
>> I'm going to answer my own post, I *think* I have something that works -
>> please check if I'm doing anything idiotic.
>>
>> Just to recap: trying to convince my company to move from svn to git, and
>> they have agreed to try one project using git as long as all commits find
>> their way to the svn repo as well.
>>
>> So I have a standard bare git repo serving the developers, a git/svn
>> "bridge" repo that performs bi-directional updates to and from svn and the
>> bare git repo.
>>
>> Ok, here's what I've done
>>
>> Create bridge
>> -------------
>> $ git svn init -s file:///path_to_svn /path_to_git_svn_bridge/
>> $ cd /path_to_git_svn_bridge
>> $ git svn fetch --authors-file=/tmp/authors.map
>>
>> Configure bare repo
>> -------------------------------
>> create bare repo that developers will use
>> $ git init --shared=all --bare /path_to_git_repo.git
>>
>> configure bridge
>> ----------------
>> $ git remote add -f -m master origin /path_to_git_repo.git
>> $ git push origin master
>> $ git branch --set-upstream master origin/master
>>
>> this branch will be used to perform svn rebases and fetches
>> $ git checkout -t -b svn svn/trunk
>>
>>
>> Workflow
>> --------
>> Developer A clones from /path_to_git_repo.git, does some work, commits and
>> pushes back to origin
>>
>> Now, in the bridge repo, fetch changes from origin (where developer A
>> pushed)
>> $ git checkout master
>> $ git pull
>>
>> Replay all changes manually, in order, onto svn branch
>> $ git checkout svn
>> $ git rev-list --reverse heads/master@{1}..heads/master | while read rev; do
>>         git cherry-pick -n $rev
>>   done
>>
>> Create one commit for all changes and synchronise with svn
>> $ git commit -am "cherry pick merge"
>> $ git svn rebase
>> $ git svn dcommit
>>
>> Now merge in anything picked up from svn, plus the rebased final commit
>> $ git checkout master
>> $ git merge svn
>>
>> Send back to bare repo (at least the final merge commit)
>> $ git push
>>
>> It seems to handle changes and preserves linear history on both sides ok.
>> Can anyone see anything obviously wrong with this approach?
>>
>> thanks,
>>
>> Will
>>
>>
>>
>>
>>
>>
>> William Hall wrote:
>>> Thanks Steven,
>>>
>>> The noMetadata option will prevent me from doing anything other than a
>>> one-shot import, which is not what I want. I need to somehow devise a
>>> workflow that allows me bidirectional push/pull between an svn repo and a
>>> remote git repo.
>>>
>>>
>>>
>>> Steven Michalske wrote:
>>>> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
>>>>
>>>>> The issue is the dcommit operation from the bridge. The rebase part of
>>>>> this re-writes the commit messages to include the SVN commit-ids which is
>>>>> nice, but screws up the push/pulls between the bridge and the bare repo.
>>>>
>>>> Look into svn.noMetadata configuration option.  It will prevent you from
>>>> rebuilding the svn to git bridge if something seriously goes wrong, but it
>>>> prevents the messages from changing.
>>>>
>>>> svn-remote.<name>.noMetadata
>>>> This gets rid of the git-svn-id: lines at the end of every commit.
>>>> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able
>>>> to rebuild it and you won't be able to fetch again, either. This is fine for
>>>> one-shot imports.
>>>> The git svn log command will not work on repositories using this, either.
>>>> Using this conflicts with the useSvmProps option for (hopefully) obvious
>>>> reasons
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe git" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>> William Hall wrote:
>>>
>>> Thanks Steven,
>>>
>>> The noMetadata option will prevent me from doing anything other than a
>>> one-shot import, which is not what I want. I need to somehow devise a
>>> workflow that allows me bidirectional push/pull between an svn repo and a
>>> remote git repo.
>>>
>>>
>>>
>>> Steven Michalske wrote:
>>>>
>>>> On Jun 16, 2010, at 4:02 PM, William Hall wrote:
>>>>
>>>>> The issue is the dcommit operation from the bridge. The rebase part of
>>>>> this re-writes the commit messages to include the SVN commit-ids which is
>>>>> nice, but screws up the push/pulls between the bridge and the bare repo.
>>>>
>>>> Look into svn.noMetadata configuration option.  It will prevent you from
>>>> rebuilding the svn to git bridge if something seriously goes wrong, but it
>>>> prevents the messages from changing.
>>>>
>>>> svn-remote.<name>.noMetadata
>>>> This gets rid of the git-svn-id: lines at the end of every commit.
>>>> If you lose your .git/svn/git-svn/.rev_db file, git svn will not be able
>>>> to rebuild it and you won't be able to fetch again, either. This is fine for
>>>> one-shot imports.
>>>> The git svn log command will not work on repositories using this, either.
>>>> Using this conflicts with the useSvmProps option for (hopefully) obvious
>>>> reasons
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe git" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe git" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>

Re: SVN migration

[William Hall]

http://github.com/innerhippy/svnAndGit

I've created a new project on github called svnAndGit that attempts to 
create a bi-directional workflow to enable git and SVN to live side-by-side.

It's not perfect by any means, so all comments most welcome!

Re: SVN migration

[David Bainbridge]

Hi William,

I have been following this thread with interest so I thought that I
would just throw in my thoughts!

While maintaining synchronization with Git is part of what is needed I
suspect that this will not entirely convince the management of your
company that Git is the way forward.

They probably see Svn as a safe repository ... The company's assets
(intellectual property) are on a central server that is backed up, and
the contents of that repository can be audited and so on. They may be
thinking about things like SOX compliance too.

So if you want them to accept Git as a replacement for svn then you
need to understand and address these concerns. This means that you
will have to have a conversation with them. To a large extent this a
people thing ... technical solutions won't necessary convince them.
They are running a company based on the knowledge and information they
own - and they want to make sure that it doesn't get lost, stolen,
corrupted, or whatever. And they are accountable to the shareholders
for this.

Also, you say that they have been using Svn for donkey's years, so
from a corporate perspective it probably does what they want and need.
Otherwise THEY would have decided to change it.

I am in a similar situation and while developers clearly want to use
gIt, the motivation from a corporate perspective is less clear and can
be perceived as introducing risk. So we are looking at the wya in
which repositories are set up, the topology of git repository
networks, use of Gitosis. Gitolite and Gitorious, and so on, to
provide some security in the corporate environment.

Every company will have a different view of this so there is no
'right' answer. A lot depends on the type of product you produce and
how long it will need to be supported. If you have products that need
to be supported for 10 years or more then promoting a tool that is 5
years old may also raise some eyebrows! You need to have the answers
ready :-)

Get it right and you will be seen as a hero who understands the
business. Get it wrong and you will consigned to the religious nerd
category who just wants to promote his favourite tool ... which I
would hope is not the case :-)

Good luck with this ... you are not alone!

Dave Bainbridge

Re: SVN migration

[William Hall]

Hi David,
Thanks for your thoughts!

I agree with your points. To an extent, management don't really care how 
we implement SCM - as long as it's effective and secure they will trust 
the "tech-wranglers" to do the right thing and not impede upon the 
company's workflow. Fortunately the industry in which I work is VFX, so 
"cutting edge" software is at the core of what we do. I am not imposing 
Git because of my own personal preference, I honestly believe that SVN 
is simply not the right tool for the job - which will increasingly 
involve multi-site collaboration that spans departments as well as 
timezones. The ability for two disparate teams of developers to 
collaborate effectively without polluting the global codebase is essential.

The limitations with SVN are becoming more and more apparent - 
especially now that we have now embarked upon a fairly radical shake-up 
of our existing software stack.

I have explained all this with senior management, some who have heard of 
Git (and its reputation) and they pretty much say "about time too".

The hard part is that we have two tiers of developers - core software 
techies (C++, python) and scripters (python, MEL - these are the people 
who make VFX movies, for example, happen). The former will have no 
problem with Git, the latter probably just don't care - they just want 
to check stuff in and out.)

What I need to do is create this hybrid system that enables the 
scripters to pretty much carry on as usual, and to provide the necessary 
tools to do SCM more effectively - ie without the overhead of a brittle 
SVN environment. If all goes well, we'll take the plunge and make the 
switch permanent.

Yes, the technical sell for Git is the easy part, the cultural sell will 
be harder. It's up to me to make the business case to the bean-counters 
and make the technical transition painless. So far, so good.

I've posted this before, the scripts I am using are available at -

http://github.com/innerhippy/svnAndGit

The more eyes on this the better...

Cheers

Will




On 03/07/10 12:37, David Bainbridge wrote:
> Hi William,
>
> I have been following this thread with interest so I thought that I
> would just throw in my thoughts!
>
> While maintaining synchronization with Git is part of what is needed I
> suspect that this will not entirely convince the management of your
> company that Git is the way forward.
>
> They probably see Svn as a safe repository ... The company's assets
> (intellectual property) are on a central server that is backed up, and
> the contents of that repository can be audited and so on. They may be
> thinking about things like SOX compliance too.
>
> So if you want them to accept Git as a replacement for svn then you
> need to understand and address these concerns. This means that you
> will have to have a conversation with them. To a large extent this a
> people thing ... technical solutions won't necessary convince them.
> They are running a company based on the knowledge and information they
> own - and they want to make sure that it doesn't get lost, stolen,
> corrupted, or whatever. And they are accountable to the shareholders
> for this.
>
> Also, you say that they have been using Svn for donkey's years, so
> from a corporate perspective it probably does what they want and need.
> Otherwise THEY would have decided to change it.
>
> I am in a similar situation and while developers clearly want to use
> gIt, the motivation from a corporate perspective is less clear and can
> be perceived as introducing risk. So we are looking at the wya in
> which repositories are set up, the topology of git repository
> networks, use of Gitosis. Gitolite and Gitorious, and so on, to
> provide some security in the corporate environment.
>
> Every company will have a different view of this so there is no
> 'right' answer. A lot depends on the type of product you produce and
> how long it will need to be supported. If you have products that need
> to be supported for 10 years or more then promoting a tool that is 5
> years old may also raise some eyebrows! You need to have the answers
> ready :-)
>
> Get it right and you will be seen as a hero who understands the
> business. Get it wrong and you will consigned to the religious nerd
> category who just wants to promote his favourite tool ... which I
> would hope is not the case :-)
>
> Good luck with this ... you are not alone!
>
> Dave Bainbridge

Re: SVN migration

[David Bainbridge]

Hi Will,

You seem to have all the bases covered :-)

It seems like they have been continuing to use SVN just because it was
there, and there was no one willing or able to take them somewhere
else, even when the business was changing around them.

The geographical distribution is an interesting one, because somehow
someone needs to understand what progress is being made with the
product development. With Git it can be easy for people to hide their
'dirty little secrets' for far too long. This doesn't really matter in
open source development, but is an issue for in a commercial
situation.

I tend to prefer a central repository and then judge progress by what
is there. If it isn't there it hasn't been done ...

Unfortunately Git books are not so hot on this aspect of deploying Git :-(

Maybe there are some other ideas out there ...

All the best,

David Bainbridge
Sweden









On 4 July 2010 19:55, William Hall <will@gnatter.net> wrote:
> Hi David,
> Thanks for your thoughts!
>
> I agree with your points. To an extent, management don't really care how we
> implement SCM - as long as it's effective and secure they will trust the
> "tech-wranglers" to do the right thing and not impede upon the company's
> workflow. Fortunately the industry in which I work is VFX, so "cutting edge"
> software is at the core of what we do. I am not imposing Git because of my
> own personal preference, I honestly believe that SVN is simply not the right
> tool for the job - which will increasingly involve multi-site collaboration
> that spans departments as well as timezones. The ability for two disparate
> teams of developers to collaborate effectively without polluting the global
> codebase is essential.
>
> The limitations with SVN are becoming more and more apparent - especially
> now that we have now embarked upon a fairly radical shake-up of our existing
> software stack.
>
> I have explained all this with senior management, some who have heard of Git
> (and its reputation) and they pretty much say "about time too".
>
> The hard part is that we have two tiers of developers - core software
> techies (C++, python) and scripters (python, MEL - these are the people who
> make VFX movies, for example, happen). The former will have no problem with
> Git, the latter probably just don't care - they just want to check stuff in
> and out.)
>
> What I need to do is create this hybrid system that enables the scripters to
> pretty much carry on as usual, and to provide the necessary tools to do SCM
> more effectively - ie without the overhead of a brittle SVN environment. If
> all goes well, we'll take the plunge and make the switch permanent.
>
> Yes, the technical sell for Git is the easy part, the cultural sell will be
> harder. It's up to me to make the business case to the bean-counters and
> make the technical transition painless. So far, so good.
>
> I've posted this before, the scripts I am using are available at -
>
> http://github.com/innerhippy/svnAndGit
>
> The more eyes on this the better...
>
> Cheers
>
> Will
>
>
>
>
> On 03/07/10 12:37, David Bainbridge wrote:
>>
>> Hi William,
>>
>> I have been following this thread with interest so I thought that I
>> would just throw in my thoughts!
>>
>> While maintaining synchronization with Git is part of what is needed I
>> suspect that this will not entirely convince the management of your
>> company that Git is the way forward.
>>
>> They probably see Svn as a safe repository ... The company's assets
>> (intellectual property) are on a central server that is backed up, and
>> the contents of that repository can be audited and so on. They may be
>> thinking about things like SOX compliance too.
>>
>> So if you want them to accept Git as a replacement for svn then you
>> need to understand and address these concerns. This means that you
>> will have to have a conversation with them. To a large extent this a
>> people thing ... technical solutions won't necessary convince them.
>> They are running a company based on the knowledge and information they
>> own - and they want to make sure that it doesn't get lost, stolen,
>> corrupted, or whatever. And they are accountable to the shareholders
>> for this.
>>
>> Also, you say that they have been using Svn for donkey's years, so
>> from a corporate perspective it probably does what they want and need.
>> Otherwise THEY would have decided to change it.
>>
>> I am in a similar situation and while developers clearly want to use
>> gIt, the motivation from a corporate perspective is less clear and can
>> be perceived as introducing risk. So we are looking at the wya in
>> which repositories are set up, the topology of git repository
>> networks, use of Gitosis. Gitolite and Gitorious, and so on, to
>> provide some security in the corporate environment.
>>
>> Every company will have a different view of this so there is no
>> 'right' answer. A lot depends on the type of product you produce and
>> how long it will need to be supported. If you have products that need
>> to be supported for 10 years or more then promoting a tool that is 5
>> years old may also raise some eyebrows! You need to have the answers
>> ready :-)
>>
>> Get it right and you will be seen as a hero who understands the
>> business. Get it wrong and you will consigned to the religious nerd
>> category who just wants to promote his favourite tool ... which I
>> would hope is not the case :-)
>>
>> Good luck with this ... you are not alone!
>>
>> Dave Bainbridge
>