ecological 3.1.0

Getting Started

Ecological lets you read and convert environment variables according to your configuration class definition.

For example, imagine that your application has a configurable integer port, a boolean debug flag, and a string log_level that defaults to INFO. You could declare your configuration as follows:

class Configuration(ecological.Config):
    port: int
    debug: bool
    log_level: str = "INFO"

And then set the environment variables PORT, DEBUG and LOG_LEVEL. Ecological will automatically set the class properties from the environment variables with the same (but upper cased) name.

By default, Ecological sets the values at class definition time and assigns them to the class itself, so you do not need to instantiate the class. If needed, you can change this behavior (see the Autoloading section).

Typing Support

You can use Ecological with several types defined in PEP484, for example:

class Configuration(ecological.Config):
    list_of_values: List[str]

Will automatically parse the environment variable value as a list.

Prefixed Configuration

You can also decide to prefix your application configuration, for example, to avoid collisions:

class Configuration(ecological.Config, prefix='myapp'):
    home: str

In this case, the home property will be read from the MYAPP_HOME environment variable.

Nested Configuration

Ecological.Config also supports nested configurations, for example:

class Configuration(ecological.Config):
    integer: int

    class Nested(ecological.Config, prefix='nested'):
        boolean: bool

This way you can group related configuration properties hierarchically.

Advanced

my_source = {"KEY1": "VALUE1"}

class Configuration(ecological.Config, transform=lambda v, wt: v, wanted_type=int, ...):
    my_var1: WantedType = ecological.Variable(transform=lambda v, wt: wt(v), source=my_source, ...)
    my_var2: str
    # ...

class Configuration(ecological.Config):
    port: int
# Values already read and set at this point.
# assert Configuration.port == <value-of-PORT-env-var>

class Configuration(ecological.Config, autoload=ecological.Autoload.NEVER):
    port: int
# Values not set at this point.
# Accessing Configuration.port would throw AttributeError.

Configuration.load()
# Values read and set at this point.
# assert Configuration.port == <value-of-PORT-env-var>

class Configuration(ecological.Config, autoload=ecological.Autoload.OBJECT):
    port: int
# Values not set at this point.

config = Configuration()
# Values read and set at this point on ``config``.
# assert config.port == <value-of-PORT-env-var>
# Accessing ``Configuration.port`` would throw AttributeError.

Caveats and Known Limitations

• Ecological doesn’t support (public) methods in Config classes