Installing Perl Modules


When you need to install Perl modules locally for a project, nothing beats Carton and Cpanminus.

When I need to install Perl modules, I usually do this from CPAN directly without relying on the modules shipped with Debian. This allows me fine control over versions, etc., at the cost of not installing those modules in any place known to system perl.

(Sometimes I also find it useful to install my own perl too, but this is for another time).

To install modules locally for a project there are two very easy ways, i.e. Carton and Cpanminus. You don’t have to (explicitly) use both, and if you can go with Carton alone it’s probably the fastest way.

cpanfile, where your needs are explicit

Both tools (can) rely on a cpanfile, i.e.

A format for describing CPAN dependencies for Perl applications

This can be as easy as just list your needs in a clear way, like this:

requires 'Log::Log4perl::Tiny';
requires 'Try::Catch', '1.1.0';

carton, quick and to the point

If you can, just stick with Carton and you’re a word away from having your modules installed:

shell$ carton
Installing modules using /home/poletti/tmp/cpanfile
Successfully installed ExtUtils-Config-0.008
Successfully installed ExtUtils-InstallPaths-0.012
Successfully installed ExtUtils-Helpers-0.026
Successfully installed Module-Build-Tiny-0.039
Successfully installed Log-Log4perl-Tiny-1.4.0
Successfully installed Try-Catch-v1.1.0
6 distributions installed
Complete! Modules were installed into /home/poletti/tmp/local

This will also produce a file cpanfile.snapshot that you might want to put under version control.

Installing Carton can take time and effort though, this is why I find it useful to keep an old standalone carton script around.

cpanm, elegant and fast

If you don’t want to use Carton for some reason, your best fallback choice is cpanm. A way to install modules quickly is to jump tests, like this:

shell$ cpanm -l local --notest --installdeps .
--> Working on .
Configuring /home/poletti/tmp ... OK
==> Found dependencies: Try::Catch, Log::Log4perl::Tiny
--> Working on Try::Catch
Fetching ... OK
Successfully installed Log-Log4perl-Tiny-1.4.0
<== Installed dependencies for .. Finishing.
6 distributions installed

Installing cpanm is much easier than Carton, there’s even a suggested way to just get the standalone executable:

cd ~/bin
curl -L -o cpanm
chmod +x cpanm

You can also find an old standalone cpanm here.

Time’s up

This is all I wanted to scribble about installing Perl modules… it should not take unnecessary time for us to do it, nor to realize how to do it!

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