Added CORS config

Gemfile

@@ -7,6 +7,7 @@ gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
 gem 'sqlite3'
 # Use Puma as the app server
 gem 'puma', '~> 3.0'
+gem 'rack-cors', '~> 0.4.0'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production

Gemfile.lock

@@ -89,6 +89,7 @@ GEM
     procto (0.0.3)
     puma (3.6.0)
     rack (2.0.1)
+    rack-cors (0.4.0)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (5.0.0.1)
@@ -178,6 +179,7 @@ DEPENDENCIES
   byebug
   listen (~> 3.0.5)
   puma (~> 3.0)
+  rack-cors (~> 0.4.0)
   rails (~> 5.0.0, >= 5.0.0.1)
   rails_best_practices (~> 1.16.0)
   reek (~> 3.4.0)

README.md

@@ -7,4 +7,5 @@
 3. `bundle install`
 4. `rake db:create`
 5. `rake db:migrate`
-6. `rails s`
+6. [Optional] Set your [frontend URL](https://github.com/cyu/rack-cors#origin) in `config/initializers/rack_cors.rb`
+7. `rails s`

config/initializers/rack_cors.rb

@@ -0,0 +1,10 @@
+module App
+  class Application < Rails::Application
+    config.middleware.insert_before 0, Rack::Cors do
+      allow do
+        origins '*'
+        resource '*', headers: :any, methods: [:get, :post, :options, :put, :delete]
+      end
+    end
+  end
+end