Hacking Thy Fearful Symmetry

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Picking Packages With Pass-through, Proxied Pinto

January 3, 2013
perl pinto

Edit: Jeffrey reminded me of a much easier way to accomplish the proxy dance. Look at the end of this entry for a new, shocking ending to this tale.

A long time ago, I wrote a small Catalyst app called dpanneur, a CPAN proxy which main goal was to cache requested modules so that I could quickly seed a local darkpan mirror. Since then technology marched on and the magnificent Pinto made its entrance. Pinto is miles and leagues superior to anything I could ever dream to achieve with dpanneur, so it's with a total lack of regrets that I declared that the king is dead, long live the Pinto.

Well, almost with a total lack of regrets. While adding any module to a Pinto repository is only a


$ pinto pull Git::CPAN::Patch

away, it's still one command to type. Wouldn't be nice to be able to have a proxy mode, just like dpanneur had? Well, as it turns out, thanks to the beautifully clean innards of Pinto, such a proxy is a small Dancer app away:


package PintoProxy;

use Dancer ':syntax';

use CPAN::Cache;
use Path::Class;
use Pinto;

# workaround for silly RT55160
*CPAN::Cache::_static = *CPAN::Cache::static;

# the stack that will absorb our proxied packages
my $stack = 'proxy';
my $pinto_dir = dir( $ENV{PINTO_REPOSITORY_ROOT}, $stack );

my $pinto = Pinto->new( root => $ENV{PINTO_REPOSITORY_ROOT} );

my $cache = CPAN::Cache->new(
    remote_uri => 'http://search.cpan.org/CPAN/',
    local_dir  => 'public',   # to take advantage of the default behavior
                              # of 'send_file'
);

# we want to get the list of modules fresh from CPAN
get '/modules/02packages.details.txt.gz' => sub {
    my $file = $cache->mirror( request->path ) 
        or return send_error 400;

    return send_file(request->path);
};

get '/**' => sub {
    my $path = request->path;

    my $pinto_path = $pinto_dir->file($path);

    unless ( -f $pinto_path ) {  
        # not there? Try to pull

        ( my $target = $path ) =~ s#/authors/id/./../##;

        $pinto->run( 'pull', norecurse => 1, stack => $stack, targets => [ $target ] );
    }

    return send_file $pinto_dir->file($path), system_path => 1;
};

true;

And indeed:


$ pinto list -s bleeding | grep Acme::EyeDrops

$ alias darkpan='cpanm --mirror http://localhost:3000/ --mirror-only'

$ darkpan Acme::EyeDrops
--> Working on Acme::EyeDrops
Fetching http://localhost:3000/authors/id/A/AS/ASAVIGE/Acme-EyeDrops-1.60.tar.gz ... OK
Configuring Acme-EyeDrops-1.60 ... OK
Building and testing Acme-EyeDrops-1.60 ... OK
Successfully installed Acme-EyeDrops-1.60
1 distribution installed

$ pinto list -s bleeding | grep Acme::EyeDrops
rf  Acme::EyeDrops

Tadah!

Or, Y'know, You Could Have Done It the Easy Way...

... by using what pinto already provides:


$ alias darkpan='pinto install --message="proxy import" -v --pull '

$ darkpan Acme::EyeDrops
Pulling distribution http://cpan.perl.org/authors/id/A/AS/ASAVIGE/Acme-EyeDrops-1.60.tar.gz
Pulling distribution http://cpan.perl.org/authors/id/P/PE/PETDANCE/Test-Pod-Coverage-1.08.tar.gz
Pulling distribution http://cpan.perl.org/authors/id/R/RC/RCLAMP/Pod-Coverage-0.22.tar.gz
Pulling distribution http://cpan.perl.org/authors/id/A/AN/ANDK/Devel-Symdump-2.08.tar.gz
Acme::EyeDrops is up to date. (1.60)

To my defense, last time I had checked the argument --message wasn't there yet and pinto was forcefully asking for a commit message, which was kinda spoiling the transparent proxy thing.

Note that this method and mine are very similar, but will exhibit some slight differences in behavior due to the fact that mine is querying CPAN directly, and this one here goes through Pinto's database. Caveat Emptor and all that, as usual.

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About the author

Yanick Champoux
Perl necrohacker , ACP writer, orchid lover. Slightly bonker all around. he/him/his