When deploying to Openshift this is what the database.yml should look like

database.yml

# MySQL.  Versions 4.1 and 5.0 are recommended.
#
# Install the MYSQL driver
#   gem install mysql2
#
# Ensure the MySQL gem is defined in your Gemfile
#   gem 'mysql2'
#
# And be sure to use new-style password hashing:
#   http://dev.mysql.com/doc/refman/5.0/en/old-client.html

production:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  pool: 5
  database: <%=ENV['OPENSHIFT_APP_NAME']%>
  username: <%=ENV['OPENSHIFT_MYSQL_DB_USERNAME']%>
  password: <%=ENV['OPENSHIFT_MYSQL_DB_PASSWORD']%>
  host:   <%=ENV['OPENSHIFT_MYSQL_DB_HOST']%>
  port:   <%=ENV['OPENSHIFT_MYSQL_DB_PORT']%>