Environments

In a lot of projects, if not all of them, the environment variables are used for deployments or to simply not to expose the secrets in the codebase.

There are many libraries you can use to make your life esier like load_env, for example.

Although these libraries are powerful, they might lack in simplicity of use and to help you with that, Lilya is shipped with a EnvironLoader functionality.

from lilya.environments import EnvironLoader

The EnvironLoader

This object is simply a wrapper on top of the already used multidict which does a lot of magic for us.

The purpose of the EnvironLoader is to make the process of loading and parsing simpler and direct for you without extra complications.

How to use it

The configurations of the application should be stored inside environment variables, for example, inside an .env file.

A good example of this practice is the access to a specific database, you don't want to hard code the credentials directly!

The EnvironLoader reads from the .env as well as from the system environments. See the order of priority for more details.

There are two ways of using the EnvironLoader.

• Via env().
• Via direct access.

Let us assume we have an .env file containing the following values and store them in a settings object specific from Lilya.

.env

DATABASE_NAME=mydb
DATABASE_USER=postgres
DATABASE_PASSWD=postgres
DATABASE_HOST=a-host-somewhere.com
DATABASE_PORT=5432
API_KEY=XXXXX

Let us see how we can use both approaches to extract the values.

Via env()

For those familiar with external libraries, this way follows the same principle. Very easy to understand and use.

from dataclasses import dataclass

from lilya.conf.global_settings import Settings
from lilya.environments import EnvironLoader

loader = EnvironLoader()


@dataclass
class DatabaseSettings(Settings):
    database_name: str = loader("DATABASE_NAME", cast=str, default="mydb")
    database_user: str = loader("DATABASE_USER", cast=str, default="postgres")
    database_password: str = loader("DATABASE_PASSWD", cast=str, default="postgres")
    database_host: str = loader("DATABASE_HOST", cast=str, default="localhost")
    database_port: int = loader("DATABASE_PORT", cast=int, default=5432)
    api_key: str = loader("API_KEY", cast=str, default="")

Via direct access

With direct access is pretty much the same but without calling the env() function.

from dataclasses import dataclass

from lilya.conf.global_settings import Settings
from lilya.environments import EnvironLoader

loader = EnvironLoader()


@dataclass
class DatabaseSettings(Settings):
    database_name: str = loader("DATABASE_NAME", cast=str, default="mydb")
    database_user: str = loader("DATABASE_USER", cast=str, default="postgres")
    database_password: str = loader("DATABASE_PASSWD", cast=str, default="postgres")
    database_host: str = loader("DATABASE_HOST", cast=str, default="localhost")
    database_port: int = loader("DATABASE_PORT", cast=int, default=5432)
    api_key: str = loader("API_KEY", cast=str, default="")

Order of priority

There is an order of priority in how the EnvironLoader operates and reads the values:

• From an environment variable.
• From an .env file declared.
• From the default value given in loader.

Parameters

• env_file - A string path of the location .env.
• environ - Optional dictionary containing specific environment variables. It defaults to os.environ if nothing is provided.
• prefix - A string prefix to be concatenated to all the loaded environment variables.
• ignore_case - Boolean flag indicating if an environment variable can be in lowercase. Defaults to false and internally transforms all the lowercase variables into uppercase().