我应该在生产Knex构建中指定什么主机以部署在heroku上？

Question

我有一个如下所示的knexfile：

module.exports = {

  testing: {
    client: 'postgresql',
    connection: {
      database: 'poker_handsdb'
    },
    pool: {
      min:2,
      max: 10
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  },

  development: {
    client: 'postgresql',
    connection: {
      database: 'poker_handsdb',
    },
    pool: {
      min: 2,
      max: 10
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  }, 

  production: { 
    client: 'postgresql', 
    connection: {
      database: 'poker_handsdb',
    },
    pool: {
      min: 2,
      max: 10
   },
    migrations: {
      tableName: 'knex_migrations'
    }
  }
}; 

我将应用程序部署到了heroku，当我尝试运行knex migration：latest时，出现以下错误：  连接ECONNREFUSED 127.0.0.1:5432

要让生产版本在heroku上运行，我需要指定什么作为主机/数据库？我试图在heroku上运行本地托管的postgres实例是否有意义？