Laravel 5 gets its enviroment related variables from the .env file located in the root of your project. You just need to set APP_ENV to whatever you want, for example:
APP_ENV=development
This is used to identify the current enviroment. If you want to display errors, you’ll need to enable debug mode in the same file:
APP_DEBUG=true
The role of the .env file is to allow you to have different settings depending on which machine you are running your application. So on your production server, the .env file settings would be different from your local development enviroment.