Ruby "bundle install" error on Openshift - ruby-on-rails

Question

I'am fairly new in Ruby and terms of deploying app through remote tools. I've tried to deploy my App on free openshift account. And I connot run application.
When I run application i get this error:
You have already activated rack 1.5.2, but your Gemfile requires rack 1.6.0.
Using bundle exec may solve this. (Gem::LoadError)
So I try to run bundle exec but i got another error:
Gemfile syntax error:
/var/lib/openshift/xxxxxxxxxxxxxxxxxxxxxxxxxx/app-root/runtime/repo/Gemfile:24:
syntax error, unexpected ':', expecting $end
gem 'sdoc', '~> 0.4.0', group: :doc
I think it might be because I used Ruby 2.1.5 on local and Open shift runs Ruby 2.0 by default.
I had foud this topic How can I force a bundle install on OpenShift Online when my RAILS_ENV is set to development?
but i don't know if I am doing it right. I don't even know where to put this pre_build file. I tried to put it under /var/lib/openshift/xxxxxxxxxxxxxxxxxxxxxxxxxx/app-root/runtime/repo/.openshift/action_hooks/ . But I'm not sure if runtime is right repo.
EDIT 1:
This it my Gemfile:
source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.0'
# Use sqlite3 as the database for Active Record
gem 'sqlite3'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.1.0'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby
# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
group: :doc do
gem 'sdoc', '~> 0.4.0'
end
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use Unicorn as the app server
# gem 'unicorn'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
group :development, :test do
# Call 'byebug' anywhere in the code to stop execution and get a debugger console
gem 'byebug'
# Access an IRB console on exception pages or by using <%= console %> in views
gem 'web-console', '~> 2.0'
end
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :jruby]
SOLUTION:
As #Rajarshi Das said I had to change
gem 'sdoc', '~> 0.4.0', group: :doc
into
group: :doc do
gem 'sdoc', '~> 0.4.0'
end
I don know exactly why. Maybe some syntax issues as I was using Ruby 2.1.5 on local, and had to use 2.0.0 on production. And after that I had to run gem install rails even though I used rails quick start. Finally I had to manually add to Gemfile gem 'nokogiri'. Finally I could run bundle install and application started to work.

Answer 1

You can simply solve the error by following way
group :doc do
gem 'sdoc', '~> 0.4.0'
end
For platforms
platforms :jruby, :mingw, :mswin do
gem 'tzinfo-data'
end
Remove Gemfile.lock as You have already activated rack 1.5.2, but your Gemfile requires rack 1.6.0
Then check bundle install

Answer 2

I ssh to $app_root directory
gem install rack
it worked

Answer 3

Make sure your branch is being used for deployment
rhc app-configure --deployment-branch [BRANCH]
Then in your development environment update gems
# bundle install
It will change Gemfile.lock
$ git add -A
$ git commit -am "Updating gemfile"
$ git push
Wait until deployment is updated

Answer 4

I tried most of the solutions here, but I still got stuck. What the problem was is to install bundle for the current version of ruby being used. You will want to do a gem install bundler in app-root/runtime/repo.
Then RAILS_ENV=production bundle exec rails console
You can refer to this answer