Allow deploying to heroku (#20)

* Use pg on production

* Update Gemfile.lock

* Update databse.yml

* Allow colorize to be loaded by default by ActiveSupport

Hopefully solves this error:
 !     Could not detect rake tasks
 !     ensure you can run `$ bundle exec rake -P` against your app
 !     and using the production group of your Gemfile.
 !     rake aborted!
 !     LoadError: cannot load such file -- colorize

* And update Gemfile.lock again

* Try this other thing

* Heroku is being needy

* Add procfile

* Upgrade sprockets

Fix for this message:

sh: 2: config.assets.compile: not found
 !
 !     A security vulnerability has been detected in your application.
 !     To protect your application you must take action. Your application
 !     is currently exposing its credentials via an easy to exploit directory
 !     traversal.
 !
 !     To protect your application you must either upgrade to Sprockets version "3.7.2"
 !     or disable dynamic compilation at runtime by setting:

* Have heroku automigrate

Gemfile

@@ -1,4 +1,5 @@
 source "https://rubygems.org"
+ruby "2.5.0"
 
 git_source(:github) do |repo_name|
   repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
@@ -9,7 +10,8 @@ group :production, :development, :test do
   # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
   gem "rails", "~> 5.1.5", require: false
   # Use sqlite3 as the database for Active Record
-  gem "sqlite3", require: false
+  # sqlite is disabled here because we want to use it only for development.
+  # gem "sqlite3", require: false
   # Use Puma as the app server
   gem "puma", "~> 3.7", require: false
   # Use SCSS for stylesheets
@@ -38,10 +40,19 @@ group :production, :development, :test do
   ##############################
 
   gem "activeadmin"
+  gem "colorize"
   gem "devise"
   gem "haml"
 end
 
+group :production do
+  ##############################
+  # Place all added gems below #
+  ##############################
+
+  gem "pg"
+end
+
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   # gem "byebug", platforms: [:mri, :mingw, :x64_mingw]
@@ -54,12 +65,12 @@ group :development, :test do
   ##############################
 
   gem "awesome_print", require: true
-  gem "colorize", require: false
   gem "cucumber", require: false
   gem "cucumber_lint", require: false
   gem "pry-nav", require: true
   gem "pry-rails", require: true
   gem "rubocop", require: false
+  gem "sqlite3", require: false
 end
 
 group :development do

Gemfile.lock

@@ -188,6 +188,7 @@ GEM
     parallel (1.12.1)
     parser (2.5.0.5)
       ast (~> 2.4.0)
+    pg (1.0.0)
     polyamorous (1.3.3)
       activerecord (>= 3.0)
     powerpack (0.1.1)
@@ -201,7 +202,7 @@ GEM
       pry (>= 0.10.4)
     public_suffix (3.0.2)
     puma (3.11.3)
-    rack (2.0.4)
+    rack (2.0.5)
     rack-test (0.8.3)
       rack (>= 1.0, < 3)
     rails (5.1.5)
@@ -278,7 +279,7 @@ GEM
       actionpack (> 4, < 5.2)
       activemodel (> 4, < 5.2)
     slop (3.6.0)
-    sprockets (3.7.1)
+    sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
     sprockets-rails (3.2.1)
@@ -333,6 +334,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   listen (>= 3.0.5, < 3.2)
   mdl
+  pg
   pry-nav
   pry-rails
   puma (~> 3.7)
@@ -348,5 +350,8 @@ DEPENDENCIES
   uglifier (>= 1.3.0)
   web-console (>= 3.3.0)
 
+RUBY VERSION
+   ruby 2.5.0p0
+
 BUNDLED WITH
    1.16.1

Procfile

@@ -0,0 +1,4 @@
+# https://devcenter.heroku.com/articles/getting-started-with-rails5#webserver
+web: bundle exec puma -t 5:5 -p ${PORT:-3000} -e ${RACK_ENV:-development}
+# https://mentalized.net/journal/2017/04/22/run-rails-migrations-on-heroku-deploy/
+release: bundle exec rake db:migrate

config/database.yml

@@ -21,5 +21,5 @@ test:
   database: db/test.sqlite3
 
 production:
-  <<: *default
-  database: db/production.sqlite3
+  url:  <%= ENV["DATABASE_URL"] %>
+  pool: <%= ENV["DB_POOL"] || ENV['RAILS_MAX_THREADS'] || 5 %>