What is Gitpan?
Gitpan is a project to import the entire history of CPAN (known as BackPAN) into a set of git repositories, one per distribution.
What is CPAN?
CPAN is the Comprehensive Perl Archive Network at cpan.org. It is an archive of tens of thousands of Perl modules written by thousands of authors. A good interface to it is http://metacpan.org
What is BackPAN?
In order to limit CPAN's size, authors are requested to delete old releases. BackPAN maintains all CPAN releases, even deleted ones, and is a complete history of CPAN. There are only a few BackPAN mirrors such as http://backpan.perl.org
Why is Gitpan?
CPAN (and thus BackPAN) is a pile of tarballs organized by author. It is difficult to get the complete history of a distribution, especially one that has changed authors or is released by multiple authors (for example, Moose). Because releases are regularly deleted from CPAN even sites like search.cpan.org provide an incomplete history. Having the complete history of each distribution in its own repository makes the full distribution history easy to access.
Gitpan also hopes to make patching CPAN modules easier. Ideally you simply clone the Gitpan repository and work. New releases can be pulled and merged from Gitpan.
Gitpan hopes to showcase using a repository as an archive format, rather than a pile of tarballs. A repository is far more useful than a pile of tarballs, and contrary to many people's expectations, the repository is turning out smaller.
Finally, Gitpan is being created in the hope that "if you build it they will come". Getting data out of CPAN in an automated fashion has traditionally been difficult.
Where is Gitpan?
The repositories are on github.com at http://github.com/gitpan.
Code, discussion, and issues can be had at http://github.com/evalEmpire/gitpan.
How do I access a distribution on Gitpan?
The clone URL for a given distribution is git://github.com/gitpan/.git. You can clone without a github account.
How big is BackPAN?
BackPAN (just the modules, we're not doing perl releases) contains over 230,000 archive files (mostly gzipped tarballs) representing over 35,000 distributions from over 6500 authors taking over 38 gigs of space.
How big is Gitpan?
Gitpan consists of over 35,000 repositories representing each CPAN distribution. Disk usage (garbage collected repositories with the latest version checked out checkout) is about 30 gigs. It imported over 230,000 releases with a compressed size of over 33 gigs.
Did Gitpan skip anything?
Yes. Gitpan generally skips things which are not modules, such as scripts, binary releases, patches, documentation and other randomness which has been uploaded to CPAN over the years. Gitpan also skips releases of Perl and Parrot, they are large and there are plenty of better archives for that.
Github has a limit of 100 megs per file, so Gitpan cannot archive the few files which go over that limit and will instead replace it with a dummy file indicating why it was skipped.
Gitpan skips any archives which cannot be extracted. Sometimes they are corrupt beyond repair, sometimes they can be extracted with some manual effort.
Occassionally something which is not a module will be considered of sufficient historical interest that it will be included, such as a heavily patched version of Perl for an obscure operating system, or a set of very old, well developed scripts.
Will you be adding X to Gitpan?
The primary focus is to get accurate repositories for each CPAN distribution and to make this data available for others to use. When you think "will Gitpan do X" instead think "how can I use Gitpan to build X?"
Suggestions on how to improve the data available from Gitpan heartily accepted.
How can I merge Gitpan's history with my module?
If you are the owner of a CPAN module and have an existing, but incomplete, repository you can fill in the history using Gitpan. The technique is outlined in this article. http://use.perl.org/~schwern/journal/39974
How do I update my module on Gitpan?
Gitpan will automatically pull new releases from CPAN, you don't have to do anything.
When does Gitpan update?
Updates happen about once a week. We hope to make them daily.
Where can I get a list of all the repositories?
How can I help?
See http://github.com/evalEmpire/gitpan/issues for a list of open problems.
You can also contribute by looking through imported CPAN distributions, checking for mistakes and reporting them as issues.
I'm the author of X distribution and already have a repository, would you delete the Gitpan repo?
Gitpan is intended to co-exist with, not compete with, the development repository for a distribution. It provides a consistent, easy to find interface to your releases so you don't have to.
Gitpan serves purposes different from the development repo. A Gitpan repo...
- Has a consistent location.
- Has a consistent structure.
- Uses a consistent version control system.
- Is only for releases.
- Has the entire release history.
While there are many different ways to use Gitpan, the primary use is to examine the release history of any given distribution regardless of the preferences of the distribution authors.
Gitpan tries to make it as clear as possible that it is not a development repository (descriptive text, descriptive commits, no issue tracker, no wiki) and to point the user at the proper development resources (ie. the distribution's Metacpan page).
You can make your own development repository more visible by adding a repository resource to your release meta-data. See https://metacpan.org/pod/CPAN::Meta::Spec#resources
I'm the author of X distribution, can I get commit access to Gitpan?
Sorry, no. Gitpan is intentionally read-only to provide a consistent interface over all of CPAN. Allowing developers to commit directly to Gitpan would endanger this consistency. In this sense, Gitpan is simply a read-only view on your releases.
As the developer of the project, you should continue to develop against your regular repo. However, it is helpful to fill in back history should you be missing it. You can use the release tags and dates on the Gitpan repo to place tags into your development repo. If history is completely missing, you can splice your development repository on top of the Gitpan repo. See "How can I merge Gitpan's history with my module?" above.
You could develop off a Gitpan fork, but the actual development history of your project up to this point would be lost. Merging your dev repo with Gitpan is left as an exercise for the reader to do usefully. If you tag your releases in a consistent manner and publish the location of your repository, Gitpan doesn't offer anything new to the developer.
I found a distribution that's out of date, could you update it?
If it's less than a week old, wait another week and it will probably happen as part of the normal update process.
I noticed a problem with a repository
Who do we have to thank for Gitpan?
Gitpan exists on top of a pile of pre-existing technology and services. Very little new code was written and the yaks were already well shorn.
- Elaine Ashton for instituting BackPAN.
- Jarkko, Graham Barr and the rest of the CPAN cabal.
- Andreas König for tirelessly maintaining PAUSE.
- brian d foy for spearheading BackPAN archeology.
- Léon Brocard for Parse::BACKPAN::Packages to access the backpan index and maintaining the BackPAN index.
- Linus and the git devs for git (this was tried before on SVN and guh...)
- github.com for a generous donation of space and support and angry unicorns
- Integra Telecom for donating a server.
- Yanick Champoux for git-cpan-patch which does most of the work.
- ftp.funet.fi for an rsync-able BackPAN mirror.
- Michael Schwern glued it all together.
- And all the people who contributed code and reported issues.