Creates PostgreSQL database roles.

pg_role_create.rake

# The production database uses a non-default user name for PostgreSQL
# connections. The user name corresponds to the app name. Use this Rake task to
# create the corresponding PostgreSQL role.
namespace :pg do
  namespace :role do
    task :create => :environment do
      ActiveRecord::Base.configurations.select { |env, config|
        config['adapter'] == 'postgresql'
      }.collect { |env, config|
        config['username']
      }.compact.uniq.each do |username|
        IO.popen('psql -d postgres', 'r+') do |io|
          io.puts "create role #{username} login createdb;"
          io.close_write
          puts io.readlines
        end
      end
    end
  end
end