Heroku/Dokku buildpack: Perl-Procfile

This is a Heroku buildpack that makes it easy to run any Perl application (possibly a complex one with different components) from a Procfile.

The difference in the approach versus e.g. heroku-buildpack-perl is that it does not assume that your application is necessarily a web one, so nothing gets installed in addition to what you setup. This can be e.g. useful even if you have a web application, but you want to run it with something different from Starman (e.g. use Hypnotoad with Mojolicious).

If your repository has a top-level sub-directory named either epan or dpan, it's assumed to have a CPAN-like directory structure inside (with authors and modules and all the rest) and it will be used for looking for modules. This makes it easier to ship DarkPAN modules while still being able to install the official ones from the official CPAN.

This buildpack is a fork of heroku-buildpack-perl-heroku and will hopefully be upstreamed.

Usage

Example usage in Heroku (untested):

$ ls -a
.perl-archive
cpanfile
Procfile
lib/

$ cat .perl-archive
https://github.com/polettix/heroku-buildpack-perl-procfile/releases/download/v0.1-dokku/perl-5.26.1.tar.gz

$ cat cpanfile
requires 'Plack', '1.0000';
requires 'DBI', '1.6';

$ cat Procfile
web: plackup --port $PORT -a app.psgi    

$ heroku create --stack cedar \
   --buildpack https://github.com/polettix/heroku-buildpack-perl-procfile.git

$ git push heroku master
...
-----> Heroku receiving push
-----> Fetching custom buildpack
-----> Perl/Procfile app detected
-----> Installing dependencies

The buildpack will detect that your perl-app has an Procfile in the root.

Example usage in Dokku, using a .buildpacks file inside the repository:

$ ls -a
.buildpacks
cpanfile
.git
Procfile
lib/

$ cat .buildpacks
https://github.com/polettix/heroku-buildpack-perl-procfile.git

$ cat cpanfile
requires 'Plack', '1.0000';
requires 'DBI', '1.6';

$ cat Procfile
web: plackup --port $PORT -a app.psgi    

$ ssh dokku@your-node.example.com apps:create your-app

$ git add remote dokku dokku@your-node.example.com:your-app

$ git push dokku master
...
-----> Fetching custom buildpack
-----> Perl/Procfile app detected
...

Alternatively, if you don't want to use the .buildpacks file inside the repo, you can use the suggestions provided in custom buildpacks:

$ ssh dokku@your-node.example.com config:set your-app \
    BUILDPACK_URL=https://github.com/polettix/heroku-buildpack-perl-procfile.git

Custom Perl

You can optionally put a file .perl-archive with a URI to the archive containing a suitable version of perl to be used instead of system perl. You can find two such ones in the releases of the repository, for versions 5.24.3 and 5.26.1.

If you want to create your own:

make sure it will run inside the container created by heroku/dokku (compiling in herokuish can be a good start)
pack it as a tar.gz including the upper compilation directory
name the archive the same as the directory (plus the tar.gz)
upload in some place you can reach
use the resulting URI inside .perl-archive

For example, if you compile your new perl in /path/to/perl-5.26.1, then you can create the archive like this:

tar czf perl-5.26.1.tar.gz -C /path/to perl-5.26.1

Libraries

There are several ways you can declare dependencies:

Carton
CPAN Minus
Git repositories

More info in the subsections!

Carton

If you use Carton you will feel at home. Whenever file cpanfile.snapshot is found, it is used for installing modules via carton --deployment.

If you generate a bundle of all distribution packages using carton bundle and include it in the repository that is pushed, option --cached is added during installation so that it is used. This allows you to avoid hitting the internet (e.g. if you're behind some firewall, or you want to ship private modules).

You can also provide your own version of Carton by including it in vendor/bin/carton (which is where Carton puts the fatpacked version of itself, if you ask it to do so).

CPAN Minus

This method is alternative to the Carton method above, and used only if cpanfile.snapshot is not present.

Dependencies can be declared using cpanfile (recommended) or more traditional Makefile.PL, Build.PL and META.json (whichever you can install with cpanm --installdeps), and the buildpack will install these dependencies using cpanm into ./local directory.

You can ship your own DarkPAN modules by creating a subdirectory named either epan or dpan at the top level, and shaping it in a CPAN-compatible way. Example:

$ find epan -type f | sort
epan/authors/01mailrc.txt.gz
epan/authors/id/P/PO/POLETTIX/Some-DarkPAN-Module-0.01.tar.gz
epan/modules/02packages.details.txt.gz
epan/modules/03modlist.data.gz

To create it, you might want to look into:

and probably a few more. When either (or both) directory is present, it is set as a --mirror for cpanm before http://www.cpan.org so that you can e.g. ship patched versions of official modules.

Git repositories

Independently of whether you use Carton or not, you can also install the latest and greatest from a git repository by providing a gitpanfile.

This file contains lines with the following format:

<name> <repo-url> <commit>

No empty lines, no comment lines, etc. etc. patches welcome etc. etc.

The <commit> part is optional and allows you to settle on a specific commit (otherwise the latest of the default branch is taken).

The process is simple: the repository is cloned (or pulled), the specified commit is optionally checked out, and the installation is performed recursively.

rage311 / heroku-buildpack-perl-procfile