How to make a Dist::Zilla based Perl module (or app) install files into /etc/?

Question

I maintain multiple Perl written (unix-ish) applications whose current installation process consists of a manually written Makefile and installs configuration files into /etc/.

I'd really like to switch their development to use Dist::Zilla, but so far I haven't found any Dist::Zilla plugin or feature which allows me to put given files into /etc/ when the make install (or ./Build install in case of using Module::Build instead of ExtUtils::MakeMaker) is run by the local administrator who's installing my application.

With pure ExtUtils::MakeMaker, I could define additional make targets in MY::postamble and the let the install target depend on one of them via the depend { install => … } attribute. Doing something similar, but via dzil build, would probably suffice, but I'd appreciate a more obvious way.

One orthogonal approach would be to make the application not to require the files under /etc/ to exist, but for just switching to Dist::Zilla that seems to much change in the actual code despite I only want to change the build system for now.

For the curious: the two applications I currently have in mind for switching to Dist::Zilla are xen-tools and unburden-home-dir.

Answer 1

For porting a complex module installer to Dist::Zilla, I recommend my plugins MakeMaker::Custom or ModuleBuild::Custom, depending on which installer you prefer. These allow you to keep your existing Makefile.PL or Build.PL and just have Dist::Zilla plug in necessary bits like the dependencies.

Answer 2

The best thing to do is to avoid installing files into /etc from any Perl distribution. You cannot ensure that the cpan client (or the installing user) has permissions to install there, and there can be multiple Perls installed on a system, so each one of them would clobber the /etc files of another install. You can't really prevent the file from being overwritten by a subsequent install, so you shouldn't put config data there that you don't want to lose.

You could put the config file in /etc/, if the application knows to look for it there, but you should allow for that path to be customized (say on a test system, look for the file in the local directory, or in a user's home directory).

For installing read-only module-specific data, the best practice in Perl is to install into a Perl-install-specific location, and the module to do that is File::ShareDir::Install. You can use it from Dist::Zilla using the [ShareDir] plugin, Dist::Zilla::Plugin::ShareDir. It is even included in the [@Basic] plugin bundle, so if you use [@Basic] in your dist.ini, you don't need to do anything at all, other than drop your data files into the share/ directory in your distribution repository.

To access the contents of the sharedir from code, use File::ShareDir.