I am trying to attempt your code into my project. I added component and eval_gemfile_patch scripts the lib folder of my main application. I have an admin_panel engine that is included in the main Gemfile as written in the guide:

component 'admin_panel'

Engine Gemfile looks like:

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }
gemspec
eval_gemfile './Gemfile.runtime'

Engine admin_panel.gemspec looks like:

$LOAD_PATH.push File.expand_path('lib', __dir__)
require 'admin_panel/version'

Gem::Specification.new do |spec|
  spec.name        = 'admin_panel'
  spec.version     = AdminPanel::VERSION
  spec.summary     = 'AdminPanel.'
  spec.description = 'AdminPanel provides functionality to manage project entities'

  spec.add_dependency 'activeadmin'
  spec.add_dependency 'devise'
  spec.add_dependency 'draper'
  spec.add_dependency 'dry-validation', '~> 1.5'
  spec.add_dependency 'omniauth', '~> 1.9.1'
  spec.add_dependency 'omniauth-google-oauth2'
  spec.add_dependency 'omniauth-rails_csrf_protection'
  spec.add_dependency 'rails', '~> 6.0.3', '>= 6.0.3.2'
  spec.add_dependency 'reform', '~> 2.3'
  spec.add_dependency 'sassc-rails'
  spec.add_dependency 'trailblazer', '~> 2.1'

  spec.add_development_dependency 'bundler'
  spec.add_development_dependency 'combustion', '~> 1.3'
  spec.add_development_dependency 'factory_bot'
  spec.add_development_dependency 'ffaker'
  spec.add_development_dependency 'pg'
  spec.add_development_dependency 'pry-byebug'
  spec.add_development_dependency 'rake', '~> 13.0'
  spec.add_development_dependency 'rspec', '~> 3.0'
  spec.add_development_dependency 'rspec-rails'
  spec.add_development_dependency 'strong_migrations'
end

When I run bundle install I had an error:

[!] There was an error parsing `Gemfile`: 
[!] There was an error parsing `Gemfile`: You cannot specify the same gem twice coming from different sources.
You specified that admin_panel (>= 0) should come from source at `engines/admin_panel` and source at `.`
. Bundler cannot continue.

 #  from engines/admin_panel/Gemfile:6
 #  -------------------------------------------
 #  
 >  gemspec
 #  
 #  -------------------------------------------
. Bundler cannot continue.

 #  from /app/Gemfile:171
 #  -------------------------------------------
 #  # Admin panel
 >  component 'admin_panel'
 #  -------------------------------------------

If I remove the gemspec call from the engine Gemfile, everything works fine, but it looks strange because I want to reuse this engine in other applications.
The same will happen if I use your generators and create some kind of test engine or gem. It generates engine with Gemfile with gemspec call inside. And "bundle install" will throw an error again.

Hi,

The first step I'm trying to accomplish for now is just to have runtime dependencies shared by engines to be in one place.
In order to do that, I've created a /gemfiles folder at root with *.gemfiles and then including them with eval_gemfile inside engines.

# gemfiles/http.gemfile

gem 'rest-client', '2.1.0'

# engines/authentication/Gemfile

source 'https://rubygems.org'

eval_gemfile '../../gemfiles/rails.gemfile'
eval_gemfile '../../gemfiles/http.gemfile'
...

The problem is that I need to require the rest-client at engines/authentication/lib/authentication.rb to make it available inside engine runtime:

require "authentication/version"
require "authentication/engine"

require "rest-client"

module Authentication
   ....
end

But, to make this work, I must define rest-client inside engine's .gemspec (spec.add_dependency). But if I do that, it looses the purpose of the eval_gemfile for sharing versions.

Sorry if I'm misunderstanding the concept.

Thanks.

thanks for the sharing in RailsConf and writing this up.
enjoy it and learnt a ton from you.

here a question about the engem cli usage

bin/engem cli currently only run tests in engines and gems.
and I am thinking of adapting the bin/engem and is-dirty to handle my root level end to end testing as well.

do you usually not having root level test case (e.g. feature / system tests) for pure engem rails project ?
wonder if you guys are moving the main_app into engines as well (like the attempt in https://cbra.info/ moving the root app into a folder called web_container)

@palkan Did your team figure out a way to keep the engine namespaced and NOT have to repeat the engine name as a subdirectory everywhere:

• engines/subsystem1/app/controllers/subsystem1/application_controller.rb
• engines/subsystem1/app/controllers/subsystem1/foos_controller.rb
• engines/subsystem1/app/models/subsystem1/foo.rb
• engines/subsystem1/app/api/subsystem1/foo_service.rb

shared-testing is still using common naming

change common to shared inside https://github.com/palkan/engems/tree/master/examples/gems/shared-testing

• documentation
• lib directory

Hi,

I'm trying to use engem-approach, and build upon what you've already learned, in setting up a modular monolith in rails.

I want the table names to be prefixed by the engine/subsystem name... I see table_name_prefix in engines/subystem1/lib/subsystem1.rb, but it doesn't seem to be used anywhere. Can you fill in the details on where you intended to tie that in?

Thanks