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There were two things I have wanted to do for some time now. The first was to come up with a way to quickly and easily set up a DarkPAN mirror so that we would have more control over our dependency chain at work. The second was to make a portable CPAN proxy service, so that I can always have access to my favorite modules, even if the machine I’m working on has no Internet access. Last week, I finally had a few ‘rount tuits’ to spend on this type of background itch, and the result is dpanneur (for dépanneur, French Canadian for convenience store).

Installation

As it stands, dpanneur is a very thin Catalyst application gluing together the goodiness of CPAN::Cache and MyCPAN::App::DPAN, and throwing in Git as the archive manager.

To get it running, first fetch it from Github

$ git clone git://github.com/yanick/dpanneur.git

then check that you have all the dependencies

$ perl Makefile.PL

and run the script that will create the module repository

$ ./script/create_repo

For now, the module repository is hard-coded to be in the subdirectory cpan of dpanneur. A branch called proxy is created and checked out. Eventually, I’ll use GitStore to push newly fetched modules to the repository, but for the time being if dpanneur is to be used as a proxy, that branch must remain as the one being checked out.

All that is left is to fire up the server in whichever mode you prefer (single-thread test server would do nicely for now)

$ ./script/dpanneur_server.pl

and there you are, running your first dpanneur. Congrats! :-)

Using it as a caching proxy

You can use the server as a caching proxy, either for its own sake, or to seed the DarkPAN branches. To do that, you just have to configure your CPAN client to use http://yourmachine:3000/proxy:

$ cpan
cpan[1]> o conf urllist = http://localhost:3000/proxy
cpan[2]> reload index
cpan[3]> install Acme::EyeDrops
Running install for module 'Acme::EyeDrops'
Running make for A/AS/ASAVIGE/Acme-EyeDrops-1.55.tar.gz
Fetching with LWP:
    http://localhost:3000/proxy/authors/id/A/AS/ASAVIGE/Acme-EyeDrops-1.55.tar.gz
etc..

As the modules are downloaded, they are also saved and committed within the repo

[dpanneur]$ cd cpan

[cpan (proxy)]$ git log -n 3
commit d065ad152f2204295334c5475104a3da517b6ae1
Author: Yanick Champoux <yanick@babyl.dyndns.org>
Date:   Wed Mar 10 20:32:52 2010 -0500

    authors/id/A/AS/ASAVIGE/Acme-EyeDrops-1.55.tar.gz

commit e8d2e83d1b16e2e0713d125f9a4bd2742681f859
Author: Yanick Champoux <yanick@babyl.dyndns.org>

Date:   Wed Mar 10 20:31:42 2010 -0500

    authors/id/D/DC/DCONWAY/Acme-Bleach-1.12.tar.gz

commit 7e0b4b600bac8424c519199ee96dc56ffbb177eb
Author: Yanick Champoux <yanick@babyl.dyndns.org>
Date:   Wed Mar 10 20:30:47 2010 -0500

    modules/03modlist.data.gz

Using it as a DarkPAN server

There is not much more involved to enabling DarkPAN repos. All we have to do is to create a branch with the modules we want and have the ‘dpan’ utility bundled with MyCPAN::App::DPAN generate the right files for us.

To continue with the example of the previous section, let’s say that we want a DarkPAN branch containing Acme::EyeDrops, but not Acme::Bleach. Then we’d do

                        # only necessary if you are running
                        # the server while you work on the branch
[dpanneur]$ git clone cpan cpan-work   

[dpanneur]$ cd cpan-work

                        # branch just before we imported Acme::Bleach
[cpan-work (proxy)]$ git branch pictoral 7e0b4b600bac8424c519199ee96dc56ffbb177eb

[cpan-work (proxy)]$ git checkout pictoral
Switched to branch 'pictoral'

                        # cherry-pick the Acme::EyeDrops commit
[cpan-work (pictoral)]$ git cherry-pick d065ad152f2204295334c5475104a3da517b6ae1

                        # rebuild the module list
[cpan-work (pictoral)]$ dpan

                        # commit the new 02packages.details.txt.gz
[cpan-work (pictoral)]$ git add .
[cpan-work (pictoral)]$ git commit -m "dpan processing"

                        # push back to the mothership
[cpan-work (pictoral)]$ git push origin pictoral

And that’s it. Now point the cpan client to http://yourmachine:3000/pictoral, and you’ll get the limited mirror.

cpan[1]> o conf urllist http://localhost:3000/pictoral
cpan[2]> reload index

cpan[3]> i Acme::EyeDrops
Strange distribution name [Acme::EyeDrops]
Module id = Acme::EyeDrops
    CPAN_USERID  ASAVIGE (Andrew J. Savige <asavige@cpan.org>)
    CPAN_VERSION 1.55
    CPAN_FILE    A/AS/ASAVIGE/Acme-EyeDrops-1.55.tar.gz
    UPLOAD_DATE  2008-12-02
    MANPAGE      Acme::EyeDrops - Visual Programming in Perl
    INST_FILE    /usr/local/share/perl/5.10.0/Acme/EyeDrops.pm
    INST_VERSION 1.55

cpan[4]> i Acme::Bleach
Strange distribution name [Acme::Bleach]
No objects found of any type for argument Acme::Bleach

The Itch

For many, CPAN is a Canadian Prairies-sized field of modules where it’s darn hard to separate the wheat from the chaff.

While the CPAN Ratings service is the principal and official way CPAN tries to rank its distributions, for me at least, it doesn’t quite scratch the itch because . . . 

1. not all distributions have reviews.
2. even when there are reviews, they generally don’t answer the next question: what should I use, instead?.

Read the rest of this entry . . .

CPAN Wants You!

Want to contribute to your favorite CPAN module, or maybe create your own, but don’t have the foggiest idea how to do it? Here are a few notes, tips, tricks, and links that might help you get started.

PAUSE id

While bringing awesome street cred, having a PAUSE id is strictly necessary only if you want to maintain or co-maintain a module. If you just want to contribute code, you’ll perfectly be able to do without, as it will usually be done via patches submitted to a bug tracking system, a code repository or using good ol’ email.

Becoming a co-maintainer

Becoming the co-maintainer of a module gives you the power to upload authorized releases of the modules on CPAN. To become one, the maintainer of the module simply has to promote you as such on PAUSE.

Creating a new module

You want to create your own module? Read the rest of this entry . . .

Recently, hanekomu was contemplating how to make subsequent installs of a Task::BeLike module upgrade its dependencies to their latest version.

The idea is intriguing. It’s not something you want to do for a typical module, but it makes sense in the context of Task::BeLike. If you care enough about a module to put it in your Task::BeLike, you probably care enough to want to upgrade when there’s a new version out there.

Alas, I think hanekomu’s proposed way of doing it is flawed (mind you, the debate is still going on as of the writing of this entry, and I can very well still be proven wrong). But after some pondeferous chin scratching, I might have come with a cunning alternative to it.

Read the rest of this entry . . .