[Nix-dev] Re: new possible movement to git (?)

[Shea Levy]

On 08/26/2011 07:36 AM, Michael Raskin wrote:
> <j377eb$m52$1 at dough.gmane.org>)
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>>  From my thinking, the process would be cleanest if it took the
>> following steps:
>>
>> 1. All the projects which contain references to the svn repos get
>> updated to point to where the new git repos will be
>> 2. The svn repo is rendered read-only or all committers have their write
>> access revoked
>> 3. Git repos are generated from the svn repos (each of the
>> https://svn.nixos.org/repos/nix/*) using one of the many available tools
>> for the purpose
>> 4. The newly-generated git repos are put in the locations specified in
>> step 1.
>>
>> Anyone can perform steps 1 and 3, while steps 2 and 4 require some sort
>> of administrative access to complete, but are fairly straightforward in
>> and of themselves. If we can get agreement about where the git repos
>> should go, I'll be happy to perform steps 1 and 3 (and 4, if we decide
>> to host the git repos somewhere public or on my servers for some reason)
>> myself, but without agreement on step 1 any effort on this will just be
>> wasted since everything will still default to the svn.nixos.org repos.
>>
>> I'm a bit tempted to just say "If I get no objections by two weeks from
>> now, I'll update the svn to point to a github repo until someone can set
>> the repos up on the nixos servers", but I don't know whether the policy
>> for a change this big is "if nothing is said, do it" or "if nothing is
>> said, don't do it".
>>
>> ~Shea
> We have "if nothing is said, don't do it" for far less intrusive changes
> than changes that include loss of access to some parts of data.
>
> With SVN I can easily look up which commits were initially done in
> stdenv branch and which were done in trunk. Ditto with Mercurial. But
> with git you seem to need some extra knowledge to do that after the
> proposed move.
>
> There are many arguments for hg/fossil/git, so just moving to git is
> not obviously the best solution. There are things that are better in
> SVN than in git, and we are not a kernel-sized project where we would
> be in the situation git is tuned for. So it is not a good idea to do any
> radical step without explicit support from TU Delft people.
>
>
>
Yeah, I won't actually do anything without an explicit go-ahead, though 
I'll really want to if this discussion just dies out without any 
resolution like the last time this came up.

As to the "git is not obviously the best solution": this is why I wanted 
to revive this discussion. Please, let's discuss the relative merits of 
different SCM options. Obviously ultimately the TU Delft people are 
ultimately in control of this project, but to the extent that we want 
decisions like these to be handled by the community: If the answer to 
"why haven't we switched away from svn" is simply inertia, then we 
should discuss how to overcome that inertia. If the answer is that we 
might want to stick with svn, or that we might want to switch to 
something besides git, then we should discuss the reasons for and 
against, and if we can't come to an obvious solution than maybe we 
should take a step back and discuss how decisions like this should be 
made. I'm not saying nixos needs formal processes or anything, but this 
was discussed last year and seems to have a fair amount of support but 
has never been resolved. I am pushing for git because it is from my 
(admittedly limited) knowledge the best solution, but what I care about 
more than that is making some move on this issue. That could mean Eelco 
saying that he's going to stick with subversion and that's that, it 
could mean a consensus that it is too difficult to choose which system 
to switch to so subversion wins by default, it could mean a consensus 
that we should table this discussion for a fixed period of time, etc. 
The current situation is a bit frustrating, though, since we have people 
willing to do the work involved but no definitive answer either way, 
even though those who have the authority to give a definitive answer 
have commented on the matter.