pyenvgen 0.4.0

Python tool to generate environment variables from schemas

pyenvgen

Warning: This project was vibe coded and is in early development. Expect breaking changes and incomplete features. Contributions are welcome!

Python tool to generate environment variables from YAML schemas.

1. Define variables in a YAML schema, including types, generation rules, and validation constraints.
2. Existing values are loaded from the chosen storage backend.
3. Values are generated (with existing/overridden values taking precedence), then validated.
4. The final environment is written back to the storage backend.

Installation

pip install pyenvgen

Usage

pyenvgen <schema.yaml> [-s STORAGE] [-b BACKEND] [-o KEY=VALUE ...] [--force]

Flag	Description
-s, --storage	Storage (default: stdout), path to a file to store output to.
-b, --backend	Storage backend, when the file extension is ambiguous (e.g. komodo vs toml backend).
-o, --override	Override a value via KEY=VALUE (repeatable)
--force	Regenerate all values, ignoring existing stored values

# Print to stdout
pyenvgen examples/basic.yaml

# Write to a .env file
pyenvgen examples/basic.yaml -s .env

# Override a value
pyenvgen examples/basic.yaml -o APP_PORT=9000

Schema format

variables:
  MY_VAR:
    type: str          # str | int | float | bool (default: str)
    description: "..."
    internal: false    # default: false
    generation:
      rule: default
      value: "hello"
    validation:
      length:
        min: 1
        max: 128

Variable types

str, int, float, bool

Generation rules

All string fields in generation rules are rendered as Jinja2 templates against already-generated values before execution.

• default – use a static value (supports Jinja2, e.g. "postgres://{{ HOST }}:{{ PORT }}/app")
• command – run a shell command and capture its stdout
• openssl – generate cryptographic material via the cryptography package

openssl commands

Command	Description	Key args
rsa	RSA private key (PEM or DER base64)	key_size (default 2048), encoding (pem|der_b64)
ec	EC private key	curve (secp256r1|secp384r1|secp521r1|secp256k1), encoding (pem|der_b64)
ed25519	Ed25519 private key	encoding (pem|raw_b64)
x25519	X25519 private key	encoding (pem|raw_b64, default raw_b64)
fernet	URL-safe base64 Fernet key	—
random	Random bytes	length (default 32), encoding (hex|base64|base64url)

Validation rules

Backed by marshmallow.

Rule	Applies to	Fields
length	str	min, max
range	int, float	min, max, min_inclusive, max_inclusive
one_of	any	choices: [...]
regexp	any	pattern

Storage backends

Value	Description
stdout	Print to standard output
.env	Read/write a .env file
json	Read/write a JSON file
toml	Read/write a TOML file
yaml	Read/write a YAML file
komodo	Read/write a Komodo-style TOML

Special properties

• internal: true – the variable is generated and available to Jinja2 templates but excluded from the output.