`postdeploy` script for Heroku Review Apps that replaces the default Postgres DB with a MySQL DB from ClearDB.

review-apps-postdeploy.sh

#!/app/bin/ruby

require 'platform-api'

cleardb_url = ENV['CLEARDB_DATABASE_URL']
if cleardb_url.nil? || cleardb_url == ''
  puts "Error: CLEARDB_DATABASE_URL not set"
  exit -1
end

target_app = ENV['HEROKU_APP_NAME']
puts "target_app: #{ target_app }"
mysql_url = cleardb_url.sub('mysql', 'mysql2')
puts "mysql_url: #{ mysql_url }"
heroku = PlatformAPI.connect_oauth('REDACTED')

postgres_addon = heroku.addon.list_by_app(target_app).find do |addon|
  addon.dig('addon_service', 'name') == "heroku-postgresql"
end
puts "Postgres addon: '#{ postgres_addon.inspect }'"

if postgres_addon
  puts "Deleting postgres addon..."
  heroku.addon.delete(target_app, postgres_addon["id"])
end

puts "Promoting '#{ mysql_url }' to DATABASE_URL for '#{ target_app }'..."
begin
  heroku.config_var.update(target_app, { 'DATABASE_URL' => mysql_url })
rescue Excon::Errors::UnprocessableEntity => e
  puts "#{ e.class }: #{ e.message }"
  exit (-1)
end

puts "1 DATABASE_URL: #{ ENV['DATABASE_URL'] }"
`export DATABASE_URL='#{ mysql_url }'`
puts "2 DATABASE_URL: #{ ENV['DATABASE_URL'] }"
ENV['DATABASE_URL'] = mysql_url
puts "3 DATABASE_URL: #{ ENV['DATABASE_URL'] }"