mongo initializer to load config from database.yml, authenticate if needed and ensure indexes are created

database.yml

development: &global_settings
  database: textual_development
  host: 127.0.0.1
  port: 27017

test:
  database: textual_test
  <<: *global_settings

production:
  host: hostname
  database: databasename
  username: username
  password: password
  <<: *global_settings

mongo.rb

config = YAML.load_file(Rails.root + 'config' + 'database.yml')[Rails.env]

MongoMapper.connection = Mongo::Connection.new(config['host'], config['port'], {
  :logger         => Rails.logger
})

MongoMapper.database = config['database']
if config['username'].present?
  MongoMapper.database.authenticate(config['username'], config['password'])
end

Dir[Rails.root + 'app/models/**/*.rb'].each do |model_path|
  File.basename(model_path, '.rb').classify.constantize
end
MongoMapper.ensure_indexes!

if defined?(PhusionPassenger)
  PhusionPassenger.on_event(:starting_worker_process) do |forked|
    # if using older than 0.6.5 of MM then you want database instead of connection
    # MongoMapper.database.connect_to_master if forked
    MongoMapper.connection.connect_to_master if forked
  end
end

It was pointed out to me on the Google group that you don't have to parse the database.yml yourself either. This wil suffice:

MongoMapper.setup(Rails.configuration.database_configuration, Rails.env, :logger => Rails.logger)

Assigning the Rails logger in all environments has worked fine for me, too.

Super-cool. Thanks!