text: # 3 - Configuration
  
  Configuration (credentials, database connection string, ...) should be stored in the environment.
  
  ## What does that mean for our application ?
  
  In _config/connections.js_, we define the _mongo_ connection and use MONGO_URL environment variable to pass the mongo connection string.
  
  ```node
  module.exports.connections = {
    mongo: {
      adapter: 'sails-mongo',
      url: process.env.MONGO_URL
    }
  };
  ```
  
  In _config/model.js_, we make sure the _mongo_ connection defined above is the one used.
  
  ```node
  module.exports.models = {
    connection: 'mongo',
    migrate: 'safe'
  };
  ```
  
  Those changes enable to provide a different _MONGO_URL_ very easily as it's defined in the environment.
  
  [Previous](02_dependencies.md) - [Next ](04_external_services.md)
  