Ruby gemspec
From wikinotes
Your gemspec file defines requirements, version, author etc.
A gemspec file is required to publish to rubygems.
You can reference your gemspec requirements within a Gemfile by calling the function gemspec.
Documentation
official docs https://guides.rubygems.org/specification-reference/
Build/Release Gem
gem build foo.gemspec gem push foo-0.0.0.gem
