EnvReader

Environment variables parser with types! Yes!

Every time when you make new service you need some class to receive, validate and store environment variables.

With this package it’ll be easy and funny.

Just make a class with typed fields and... that’s it.

Requirements

Python 3.7 and above. There's no additional dependencies.

Installation

pip install envreader

Simple usage

from envreader import EnvReader


class MyEnv(EnvReader):
    PATH: str
    LIST: list
    NONE_EXIST: int = 1234  # Variable with default value


e = MyEnv()

print(e.PATH)
# /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin

print(e.LIST)
# [1, 2, 3, 4]

print(e.NONE_EXIST)
# 1234

Use with transform functions

I don’t want to make a giant validation library like wonderful Pydantic. Thus EnvReader supports only simple types( bool, str, int, float, list, tuple and dict) by default. This is enough in most cases.

Transform functions allows using EnvReader for more complex cases.

from typing import List
from envreader import EnvReader, Field


class MyEnv(EnvReader):
    PATH: List[str] = Field(transform=lambda x: x.split(":"))


e = MyEnv()

print(e.PATH)
# ['/usr/local/bin', '/usr/bin', '/bin', '/usr/sbin', '/sbin']

Using static methods as a transform functions.

You may store all your helper functions inside the same class. But don’t forget to add @staticmethod decorator.

from typing import List
from envreader import EnvReader, Field


class MyEnv(EnvReader):
    @staticmethod
    def trans(x: str) -> List[str]:
        return x.split(':')

    PATH: List[str] = Field(transform=trans)


e = MyEnv()

print(e.PATH)
# ['/usr/local/bin', '/usr/bin', '/bin', '/usr/sbin', '/sbin']

Make your environment variables self-documented.

Documentation is in great demand for all good applications, right?

from envreader import EnvReader, Field


class MyEnv(EnvReader):
    PATH: str = Field("/sbin", description="Application path", example="/usr/bin:/bin:/usr/sbin:/sbin")


e = MyEnv()

print(e.help())
# PATH
#     Application path
#     Example: /usr/bin:/bin:/usr/sbin:/sbin
#     Default: /sbin

Error handling? Easy.

import sys
from envreader import EnvReader, EnvMissingError


class MyEnv(EnvReader):
    SOME_VAR: str


try:
    e = MyEnv()
except EnvMissingError as e:
    print(f"Missing required env var {e.field}")
    sys.exit(-1)
# Missing required env var SOME_VAR

Enjoy!