Include files from git submodules when building a ruby gem

Today I ran into the following situation. I wanted to build a gem with bundler which has some vendor assets included as git submodules. My directory structure was something like that

.git/
app/*
lib/*
vendor/assets/javascripts/es5-shim (submodule)
vendor/assets/javascripts/pathjs (submodule)

When doing

rake build

the files from the submodules where not included in the gem, because the gemspec specifies the files as follows.

gem.files = `git ls-files`.split($\)

Unfortunately, git ls-files does not list files from submodules and that’s why, these files are not included in the gem.

I solved this by utilizing git submodules’s foreach statement in combination with some ruby string manipulation.

The resulting gemspec looks like this.

	# -*- encoding: utf-8 -*-
	require File.expand_path('../lib/example/version', __FILE__)
	Gem::Specification.new do |gem|
	gem.authors = ["John Doe"]
	gem.email = ["john_doe@example.org"]
	gem.description = %q{Write a gem description}
	gem.summary = %q{Write a gem summary}
	gem.homepage = ""
	gem.files = `git ls-files`.split($\)
	gem.executables = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
	gem.test_files = gem.files.grep(%r{^(test|spec|features)/})
	gem.name = "example"
	gem.require_paths = ["lib"]
	gem.version = Example::VERSION
	# get an array of submodule dirs by executing 'pwd' inside each submodule
	`git submodule –quiet foreach pwd`.split($\).each do |submodule_path|
	# for each submodule, change working directory to that submodule
	Dir.chdir(submodule_path) do
	# issue git ls-files in submodule's directory
	submodule_files = `git ls-files`.split($\)
	# prepend the submodule path to create absolute file paths
	submodule_files_fullpaths = submodule_files.map do |filename|
	"#{submodule_path}/#{filename}"
	end
	# remove leading path parts to get paths relative to the gem's root dir
	# (this assumes, that the gemspec resides in the gem's root dir)
	submodule_files_paths = submodule_files_fullpaths.map do |filename|
	filename.gsub "#{File.dirname(__FILE__)}/", ""
	end
	# add relative paths to gem.files
	gem.files += submodule_files_paths
	end
	end
	end

view raw

example.gemspec

hosted with ❤ by GitHub

Matt Connolly suggested a shorter version of the gemspec. Have a look at his comment.