envo

Environment variable loading utility.

envo provides a powerful, type-safe way to manage environment variables in Python projects. It automatically discovers .env files, coerces values to appropriate types, validates against specifications, and offers both programmatic and CLI interfaces.

Features

• Load From Many Sources - .env.sample + .env.base + .other.yaml + c.json + d.toml + .env + os.environ
• Refs - ENV_VAR_B=$ENV_VAR_A
• Math - ITEM_COUNT=($MODE=="prod")?5:10
• Chaining - ENVO_EXTENDS=.env.base ENVO_EXTENDED_BY=.env.overrides
• Auto-Coerced Types - env.MY_VAL # 5 <int> automatically converts strings to int, float, bool, Path, dict, list, and more
• Validation - using @min/@max/@type/etc declarations in sample.env
• Self-Documenting - comments in the sample.env get loaded into the Env object and used/shown in commandline tools
• CLI Tools - for validating, configuring, etc.
• Path Substitution - % references the project root, and can be used for filepath env variables
• Path Fallbacks - /file-a.txt|/file-b.txt will use the firs path that exists
• Multiple file formats — Load from .env, .json, .yaml, and .toml files
• Variable grouping — Auto-detected from sample.env, helps with grabbing chunks of env variables
• Customizable — Override behavior with ENVO_* environment variables
• Supports .py env specs - Allow using .py files to specify default values

How to use?

Requirements

• Python 3.10+

Install

pip install modularizer-envo

Your job is simple:

• write a sample.env in your project root
• let the user overwrite variables using .env or by running envo config
• load in parsed variables with from envo import Env and env = Env()

Quick Start

Programmatic Usage

from envo import Env

# Auto-discover and load environment
env = Env()

# Access with automatic type coercion
debug = env.DEBUG          # bool
port = env.PORT            # int
db_url = env.DATABASE_URL  # str

# Or use the pre-built global instance
from envo import env
print(env.DEBUG)

Using a Spec File

Create a sample.env file to define your environment schema:

# sample.env - Environment Variable Specification

# =============================================================================
# database - Database Configuration
# =============================================================================
DB_HOST=localhost          # Database hostname @required
DB_PORT=5432               # Port number @type:int @range:1-65535
DB_NAME=myapp              # Database name

# =============================================================================
# server - Server Configuration  
# =============================================================================
DEBUG=false                # Enable debug mode @type:bool
PORT=8080                  # Server port @type:int
LOG_LEVEL=info             # Log level @choices:debug,info,warn,error

Then in your code:

from envo import Env

env = Env()  # Automatically uses sample.env as spec

# Values are validated and coerced according to spec
port = env.DB_PORT    # int: 5432
debug = env.DEBUG     # bool: False

CLI Commands

envo show - Display environment variables with colored output.

envo validate - Validate a .env file against a spec.

envo config - Interactive TUI for browsing and editing environment variables.

Spec File Format

Basic .env Spec

# =============================================================================
# group_name - Group Description
# =============================================================================

VARIABLE_NAME=default_value  # Documentation text @directive:value

# Supported directives:
#   @type:int|float|bool|str|path|json|list|glob
#   @min:N          - Minimum value
#   @max:N          - Maximum value
#   @range:N-M      - Range constraint
#   @choices:a,b,c  - Valid choices
#   @pattern:regex  - Regex pattern
#   @required       - Value must be non-empty

JSON/YAML Spec

# config.yaml
database:
  DB_HOST:
    default: localhost
    help: Database hostname
    required: true
  DB_PORT:
    default: 5432
    type: int
    min: 1
    max: 65535

server:
  DEBUG:
    default: false
    type: bool
  PORT:
    default: 8080
    type: int

Type Coercion

envo automatically coerces values based on content or explicit type hints:

Type	Examples	Notes
bool	true, false, 1, 0, yes, no, on, off	Case-insensitive
int	42, 1_000_000	Underscores allowed
float	3.14, 1_000.5	Underscores allowed
path	/home/user, ~/data, %/config	% = project root
dict/list	{"key": "value"}, ["a", "b"]	JSON format
null	null, none	Becomes Python None

# Explicit type override
env.get("PORT", type=int)
env.get("HOSTS", type=list)
env.get_as("CONFIG_PATH", Path)

File Chaining

Chain multiple configuration files with priority control:

# base.env - Load another file with LOWER priority (we override it)
ENVO_EXTENDS=defaults.env
DB_HOST=production-db

# .env - Load another file with HIGHER priority (it overrides us)
ENVO_EXTENDED_BY=.env.local

Priority order (lowest to highest):

1. Spec file defaults (sample.env)
2. Extended files (ENVO_EXTENDS)
3. Main .env file
4. Extending files (ENVO_EXTENDED_BY)
5. System environment variables (os.environ)

Variable References

Reference other variables with $VAR_NAME:

BASE_DIR=/app
DATA_DIR=$BASE_DIR/data
LOG_DIR=$BASE_DIR/logs
FULL_URL=http://$HOST:$PORT/api

Use % to reference the project root:

CONFIG_PATH=%/config
DATA_PATH=%/data

Expression Operators

Envo supports logical and arithmetic expressions for dynamic configuration:

Operator	Syntax	Description	Result
Ternary	$VAR?yes:no	If VAR is truthy, use "yes", else "no"	yes or no
NOT	!$VAR	Logical negation	true or false
AND	$A&&$B	Logical AND	true or false
OR	$A||$B	Logical OR	true or false
Equals	$A==$B	Equality check	true or false
Not Equals	$A!=$B	Inequality check	true or false

Note: Single | and / are NOT operators to avoid conflicts with path separators.

# Ternary - conditional values
DEBUG_MSG=$DEBUG?Debugging enabled:Production mode
DB_HOST=$USE_DOCKER?db:localhost

# Logical operators (use && and ||)
IS_READY=$DB_CONFIGURED&&$CACHE_CONFIGURED
USE_FALLBACK=$PRIMARY_DOWN||$FORCE_FALLBACK
FEATURE_OFF=!$FEATURE_ENABLED

# Comparisons
IS_PROD=$ENV==production
NOT_LOCAL=$ENV!=local

# Arithmetic
TOTAL_WORKERS=$CPU_COUNT*2
ADJUSTED_PORT=$BASE_PORT+$INSTANCE_ID

# String concatenation (when values aren't both numeric)
GREETING=$HELLO+$WORLD

# Combine with parentheses
SHOW_DEBUG=($DEBUG&&$VERBOSE)||$FORCE_DEBUG
COMPLEX_CALC=($A+$B)*$C

Truthiness: Values are truthy unless they are empty, false, 0, no, off, null, or none.

Variable Groups

Filter variables by group for organized access:

# Get all database variables
db_env = env.get_group("database")
print(db_env.DB_HOST)

# List all available groups
print(env.list_groups())

# Access all groups as a dict
for name, group_env in env.groups.items():
    print(f"{name}: {list(group_env.keys())}")

Configuration

Customize envo behavior with environment variables:

Variable	Default	Description
ENVO_DEFAULT_ENV_FILE	.env	Default env file name
ENVO_DEFAULT_SPEC_FILES	sample.env,.env.sample	Spec file search order
ENVO_DEFAULT_GROUP	unknown	Default group for ungrouped vars
ENVO_USE_SPEC_DEFAULT	<default>	Special value to use spec default
ENVO_BOOL_TRUE_VALUES	true,1,yes,on,y,enable,enabled	Values coerced to True
ENVO_BOOL_FALSE_VALUES	false,0,no,off,n,disable,disabled	Values coerced to False
ENVO_PROJECT_ROOT_CHAR	%	Character for project root substitution
ENVO_REF_CHAR	$	Character for variable references

See sample.env in the repository for the complete list of configuration options, including color scheme customization.

Advanced Usage

Custom Spec

from envo import Env

env = Env(
    ".env",
    spec={
        "PORT": int,
        "DEBUG": bool,
        "HOSTS": list,
        "DB_*": {"groups": ("database",), "type": str},
        "API_*": {"groups": ("api",), "required": True},
    }
)

Multiple Files with Priority

# Load with explicit priority order
env = Env(
    "defaults.env",      # Lowest priority
    ".env",              # Medium priority
    ".env.local",        # Highest priority
)

# Control system environment handling
env = Env(
    ".env",
    existing_env_priority="lowest",  # or "highest" (default), "none"
)

Validation Pipeline

from envo import Env
from envo.spec_type import VariableSpec

env = Env(
    spec={
        "PORT": VariableSpec(
            type=int,
            default=8080,
            validator=lambda x: x if 1 <= x <= 65535 else ValueError("Invalid port"),
        ),
        "EMAIL": VariableSpec(
            type=str,
            pattern=r"^[^@]+@[^@]+\.[^@]+$",
            required=True,
        ),
    }
)

Access Raw Values

# Get the raw string value before coercion
raw_port = env.raw["PORT"]  # "8080" (string)

# Get the parsed/coerced value
port = env.PORT  # 8080 (int)

License

Unlicense — Public Domain