In Lumen you can create a database connection by filling out the default information you can find in .env file. But if you need multiple database connections you can do so by adding a new database config file and creating a list of the new database connections.

Create a database config file /config/database.php.

Add an array of database information.

return [
    'default' => 'mysql',
    'connections' => [
        'mysql' => [
            'driver' => 'mysql',
            'host' => env('DB_HOST'),
            'database' => env('DB_DATABASE'),
            'username' => env('DB_USERNAME'),
            'password' => env('DB_PASSWORD'),
            'charset'   => 'utf8',
            'collation' => 'utf8_unicode_ci',
        ],
        'mysql2' => [
            'driver' => 'mysql',
            'host' => env('DB2_HOST'),
            'database' => env('DB2_DATABASE'),
            'username' => env('DB2_USERNAME'),
            'password' => env('DB2_PASSWORD'),
            'charset'   => 'utf8',
            'collation' => 'utf8_unicode_ci',
        ],
    ]
];

By setting a default element will allow you to choose which database to use when you call DB::connection();. By placing the env() function inside the configuration file you can manage the database credentials on a per environment basis.

To use the different databases in your code you need to define which connection you want by passing in the name of the connection by either using the app() helper function or the DB facade.

// Use default connection
app('db')->connection()->select('xx');
DB::connection()->select('yy');

// Use mysql2 connection
app('db')->connection('mysql2')->select('xx');
DB::connection('mysql2')->select('yy');