let process = require('process');

module.exports = {
  'database': {
    'host': 'localhost',
    'user': 'choirmaster',
    'password': 'choirmaster',
    'database': 'choirmaster'
  },

  'authentication': {
    'encryptionKey': 'changethisatonce'
  },

  'server': {
    'port': 4567
  }
};

if (process.env.HEROKU) {
  module.exports.database = {
    host: process.env.DATABASE_HOST,
    user: process.env.DATABASE_USER,
    password: process.env.DATABASE_PASSWORD,
    database: process.env.DATABASE_NAME
  };

  module.exports.server.port = process.env.PORT;
}

let process = require('process');

module.exports = {
  'database': {
    'host': 'localhost',
    'user': 'choirmaster',
    'password': 'choirmaster',
    'database': 'choirmaster'
  },

  'authentication': {
    'encryptionKey': 'changethisatonce'
  },

  'server': {
    'port': 4567
  },

  'email': {
    'transporter': 'gmail',
    'auth': {
      'user': 'yourgmailusername',
      'pass': 'yourgmailpassword'
    }
  }
};

if (process.env.HEROKU) {
  module.exports.database = {
    host: process.env.DATABASE_HOST,
    user: process.env.DATABASE_USER,
    password: process.env.DATABASE_PASSWORD,
    database: process.env.DATABASE_NAME
  };

  module.exports.server.port = process.env.PORT;
}

Add example email configuration to configuration.example.js