Steps to upgrade an existing Rails 4.2.x app to unreleased Rails 5 edge version

rails-5-edge-upgrade.markdown

Note: At the time of writing this the commands shown below were executed on Ubuntu 14.04

• Updated .ruby-version by replacing 2.2.1 WITH 2.2.3. In case this file is not present, its better to create it.

• Updated .ruby-gemset by replacing <MY_APP_NAME> WITH <MY_APP_NAME>-on-rails-5, where <MY_APP_NAME> represents your app's name. In case this file is not present, its better to create it.

• Upgraded rvm by running command $ rvm get stable.

• Installed latest stable Ruby version listed here using command: $ rvm install 2.2.3

• Removed Gemfile.lock

• Updated Gemfile by replacing gem 'rails', '4.2.0' WITH gem 'rails', git: 'https://github.com/rails/rails.git'

• Installed bundler using command: $ gem install bundler

• Ran bundle and encountered error:

  ```
    Bundler could not find compatible versions for gem "rack":
    In Gemfile:
      rails (>= 0) ruby depends on
        actionpack (= 5.0.0.alpha) ruby depends on
          rack (~> 2.x) ruby
    Could not find gem 'rack (~> 2.x) ruby', which is required by gem 'actionpack (= 5.0.0.alpha) ruby', in any of the sources.
  ```
  
  Found following references on this error: https://github.com/rails/rails/issues/21422
  

• Based on the reference found to get rid of the error shown above, added following to the Gemfile.

    ```
    # ================================
    # Once Rails 5 is officially released I don't think the following shall be needed. But for
    # now those are required to get rid of error reported in https://github.com/rails/rails/issues/21422
    gem 'rack', :git => 'https://github.com/rack/rack.git'
    gem 'arel', :git => 'https://github.com/rails/arel.git'
    # ================================
    ```
  

  Reference: http://www.christopherbloom.com/2015/04/26/setting-up-a-rails-5-app-from-edge/

• Ran bundle and encountered following error:

    ```
      Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
          /home/jignesh/.rvm/rubies/ruby-2.2.3/bin/ruby -r ./siteconf20151119-12203-hjmfyi.rb extconf.rb
      creating Makefile
  
      make "DESTDIR=" clean
  
      make "DESTDIR="
      compiling generator.c
      linking shared-object json/ext/generator.so
      /usr/bin/ld: cannot find -lgmp
      collect2: error: ld returned 1 exit status
      make: *** [generator.so] Error 1
  
      make failed, exit code 2
  
      Gem files will remain installed in /home/jignesh/.rvm/gems/ruby-2.2.3@<GEMSET_NAME>/gems/json-1.8.3 for inspection.
      Results logged to /home/jignesh/.rvm/gems/ruby-2.2.3@<GEMSET_NAME>/extensions/x86_64-linux/2.2.0/json-1.8.3/gem_make.out
      An error occurred while installing json (1.8.3), and Bundler cannot continue.
      Make sure that `gem install json -v '1.8.3'` succeeds before bundling.
    ```
  
    Found following reference on this error: http://stackoverflow.com/questions/32130649/can-not-install-json-gem-with-ruby-2-2-3-on-ubuntu
  

• Based on the reference found to get rid of the error shown above, ran following: $ sudo apt-get install libgmp3-dev Reference: http://stackoverflow.com/a/32191707/936494

• Ran bundle again and it ran successfully!