Re: Preservation of Guix report 2022-01-16

[Timothy Sample <samplet@ngyro.com>]

Hi,

Vagrant Cascadian <vagrant@debian.org> writes:

> On 2022-01-18, Ludovic Courtès wrote:
>> Timothy Sample <samplet@ngyro.com> skribis:
>>> A really important thing to do at this point is to verify that some
>>> reasonable looking computation is covered by what we are doing already.
>>> For instance, is every source used to build Guile (or Python or R)
>>> preserved?  This will ensure that key sources are not missing, which is
>>> a real possibility given that everything so far has been purely a
>>> numbers game!
>>
>> I wonder if we could have something similar to ‘guix weather -c’, which
>> would highlight missing sources with many dependents.

Definitely.  The simplest way to do that is to use the PoG database
as-is, and just write a script that traverses the derivation graph
checking for coverage.  It’s a bit trickier to integrate into Guix
itself, since we would have to make the data available.  It’s a good job
for the Data Service, but I feel like it’s a long road from here to
there.

>> TeX Live is a big concern: it’s all Subversion, and everything depends
>> on those packages.  IIRC, SWH does not support Subversion yet; and when
>> it does, we’ll have to adjust our code so it can actually fetch
>> Subversion checkouts from SWH.  One issue is partial checkouts: all
>> these ‘texlive-’ packages refer to partial checkouts of the big TeX Live
>> repo.
>
> Maintain a git mirror of texlive SVN using git-svn or similar, and have
> guix packages use that, and make sure SWH ingests it? Is it difficult
> because of the size of TeX Live?
>
> A little ugly, sure, but maybe only include the revisions that guix is
> interested in for starters...

Fortunately, SWH does support Subversion, so we can avoid this.  They
haven’t visited the TeX Live sources yet, but I’m sure they will
eventually.

How to actually match up what we want with what they have is a big
question!  I imagine they do quite a number to make the SVN repos fit
their Git-inspired data model.  It’s not clear to me how it works.  I’ll
have to look over the loader sometime:

https://forge.softwareheritage.org/source/swh-loader-svn/repository/master/

One way to handle things like partial checkouts is to revisit storing
SWHIDs with our origins.  If you have the directory ID, you can just
download the directory from SWH without worrying about SVN at all.  It
would also give us an easy way to handle Bazaar and CVS (which are under
development at SWH).


-- Tim