bundler permission error on Ubuntu (ruby using apt, NOT rvm) - ruby

Question

We used to have a redmine setup on an Ubuntu 12 based server but our hoster upgraded the servers and we now have to move everything to the new machine. It now runs under Ubuntu 14LTS. I've installed the LAMP package with apt as well as the redmine one and (I assume) all dependencies required (including Passenger).
I did the modifications on the Apache2 conf files and I'm now able to access the redmine site... only to get the error page showing the following:
Bundler::PermissionError (Bundler::PermissionError)
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/shared_helpers.rb:110:in `rescue in filesystem_access'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/shared_helpers.rb:108:in `filesystem_access'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/definition.rb:306:in `lock'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/runtime.rb:122:in `lock'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/runtime.rb:49:in `setup'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler.rb:101:in `setup'
/var/lib/gems/1.9.1/gems/bundler-1.15.3/lib/bundler/setup.rb:19:in `<top (required)>'
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
/usr/lib/ruby/vendor_ruby/phusion_passenger/loader_shared_helpers.rb:245:in `block in run_load_path_setup_code'
/usr/lib/ruby/vendor_ruby/phusion_passenger/loader_shared_helpers.rb:348:in `running_bundler'
/usr/lib/ruby/vendor_ruby/phusion_passenger/loader_shared_helpers.rb:243:in `run_load_path_setup_code'
/usr/share/passenger/helper-scripts/rack-preloader.rb:100:in `preload_app'
/usr/share/passenger/helper-scripts/rack-preloader.rb:158:in `<module:App>'
/usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `<module:PhusionPassenger>'
/usr/share/passenger/helper-scripts/rack-preloader.rb:28:in `<main>'
Application root
/usr/share/redmine
Environment (value of RAILS_ENV, RACK_ENV, WSGI_ENV and PASSENGER_ENV)
production
Ruby interpreter command
/usr/bin/ruby
User and groups
uid=33(www-data) gid=33(www-data) groups=33(www-data)
All the information I can get from googling relate to a manual install of Ruby using RVM or RBENV, but I did the setup through apt (and, yes, using sudo apt-get... which I now know is not good for bundler).
I know the following are installed:
redmine 2.4.2-1 (from apt)
ruby 1.9.3 (ruby -v) but it looks like gems are running with/from 1.9.1
rails 3.2.16 (rails -v)
passenger 4.0.37-2
I've tried changing chown www-data /var/lib/gems/1.9.1/gems/bundler-1.15.3 but no success.
Is there a way to correct this or should I trash all the setup and restart manually without apt?

Answer 1

From the stacktrace above this looks like the section of bundler responsible for creating a Gemfile.lock in the application root directory.
https://github.com/bundler/bundler/blob/1-15-stable/lib/bundler/definition.rb#L307
the uid and gid of your passenger process appear to be www-data - does this user have write access to /usr/share/redmine? If not, that is likely what is wrong here - your passenger process is trying to generate a Gemfile.lock but does not have permission to do so.
This is a tutorial on linux users and groups - it should give you an overview of why the above issue is occurring.
A fix would be to add www-data to the group that owns /usr/share/redmine, and then grant group-level write access recursively to that group.