Environment parser

Requirements

• Python - Minimum required version is 3.8

Using the environment parser

EnvironmentParser class parses all environment variables with certain prefix and creates a Python dictionary based on the structure of these variables. The values are converted to booleans and integers when detected as such by default.

General variable structure rules:

• variable name after prefix should not be empty
• first character of variable name after prefix should not be "_"
• different levels of depth within environment variables are specified by using "__" string.
• arrays can be specified by using numeric index as a key within particular level
• array numeric indices should be defined in order, variables with invalid index will be discarded

Value conversion rules:

• value will be converted to boolean if it matches true or false when lower cased
• value will be converted to integer if it contains digits only

Using the EnvironmentParser class

Example of instantiating of EnvironmentParser object using MYPREFIX as a prefix for environment variables. Upon instantiation, the object will automatically parse the current environment variables and store them in its configuration property.

import json
from adi_env_parser import EnvironmentParser

parser = EnvironmentParser(prefix="MYPREFIX")
print(json.dump(json.dumps(parser.configuration, indent=4)))

It is possible to provide existing JSON formatted file as a configuration base.

import json
from adi_env_parser import EnvironmentParser

parser = EnvironmentParser(prefix="MYPREFIX", config_file="configuration.json")
print(json.dump(json.dumps(parser.configuration, indent=4)))

It is possible to disable value conversion by setting convert_values parameter when instantiating EnvironmentParser object.

from adi_env_parser import EnvironmentParser

parser = EnvironmentParser(prefix="MYPREFIX", convert_values=False)

Examples

Examples use PYENV as environment variable prefix. This is default prefix used when not specifying one explicitly when instatiating EnvironmentParser.

Creating dictionary

Environment variables:

PYENV_hotel_name="Blue Falcon"
PYENV_rooms__room_1="James Holden"
PYENV_rooms__room_2="Amos Burton"
PYENV_rooms__room_3="Naomi Nagata"
PYENV_rooms__room_4="Alex Kamal"

Resulting object:

{
    "hotel_name": "Blue Falcon",
    "rooms": {
        "room_1": "James Holden",
        "room_2": "Amos Burton",
        "room_3": "Naomi Nagata",
        "room_4": "Alex Kamal"
    }
}

Creating array

Environment variables:

PYENV_hotel_name="Blue Falcon"
PYENV_room_1__inventory__0="Wardrobe"
PYENV_room_1__inventory__1="Table"
PYENV_room_1__inventory__2="Lamp"

Resulting object:

{
    "hotel_name": "Blue Falcon",
    "room_1": {
        "inventory": [
            "Wardrobe",
            "Table",
            "Lamp"
        ]
    }
}

Dictionaries within list

Environment variables:

PYENV_hotel_name="Blue Falcon"
PYENV_rooms__0__name="Room 1"
PYENV_rooms__0__capacity="2"
PYENV_rooms__2__name="Room 2"
PYENV_rooms__2__capacity="2"

Resulting object:

{
    "hotel_name": "Blue Falcon",
    "rooms": [
        {
            "name": "Room 1",
            "capacity": "2"
        },
        {
            "name": "Room 2",
            "capacity": "2"
        }
    ]
}

Console utility

Module provides console utility which can be used for parsing of environment variables. It also supports reading of existing JSON formatted file and setting indentation for output of created configuration JSON object.

➜ adi-env-parser --help
usage: adi-env-parser -p <prefix> -j <base_json_file>

Parses environment variables with defined prefix and creates JSON output from the parsed structure.

optional arguments:
  -h, --help            show this help message and exit
  --prefix [PREFIX], -p [PREFIX]
                        Environment variable prefix. Default: PYENV
  --json [JSON], -j [JSON]
                        JSON formatted file to read as base configuration
  --indent [INDENT], -i [INDENT]
                        Number of spaces to use for indentation of output JSON string
  --ignore-prefix IGNORE_PREFIX, -n IGNORE_PREFIX
                        Environment variable prefix to ignore. Can be used multiple times.

Development

Install development packages

pip install -e ".[dev]"
pip install -e ".[test]"
# Install build-local package group if you want to build packages locally
pip install -e ".[build-local]"

Install pre-commit

pre-commit install

Building and publishing new version

New version is built and published on tag in GitHub repository. The package version is infered from commit name.