This document is part of the Appwrite contributors' guide. Before you continue reading this document, make sure you have read the [Code of Conduct](https://github.com/appwrite/appwrite/blob/master/CODE_OF_CONDUCT.md) and the [Contributing Guide](https://github.com/appwrite/appwrite/blob/master/CONTRIBUTING.md).
The environment variables in Appwrite are prefixed with `_APP_`. If it belongs to a specific category, the category name is appended as `_APP_REDIS` for the Redis category. The available categories are General, Redis, MariaDB, InfluxDB, StatsD, SMTP, Storage and Functions. Finally, a properly describing name is given to the variable. For example, `_APP_REDIS_HOST` is an environment variable for Redis connection host. You can find more information on available categories and existing environment variables in the [environment variables doc](https://appwrite.io/docs/environment-variables).
First of all, we added the new environment variable to `app/config/variables.php` in the designated category. If none of the categories fit, add it to the General category. Copy the description of the existing variable to create a new one so that you will not miss any required fields.
This information is also used to generate the website documentation at https://appwrite.io/docs/environment-variables, so please use good descriptions that clearly define the purpose and other required info about the environment variable that you are adding.
If the newly introduced environment variable has a default value, add it to the `.env` and `Dockerfile` along with other environment variables. `.env` file uses settings for Appwrite development environment.
Add the new environment variables to the `docker-compose.yml` and `app/views/install/compose.phtml` for each docker service that requires access to those environment variables.
The Appwrite maintainers use the `docker-compose.yml` file during development, whereas the `app/views/install/compose.phtml` file is used by the Appwrite setup script.
With these steps, your environment variable is properly added and can be accessed inside Appwrite code and any other containers where it is passed. You can access and use those variables to implement the features you are trying to achieve.
