env-preferences

name	env-preferences
description	Reusable APP_ENV env-file pattern for local development. Commit template.env, keep dev/test/prod env files local-only, and load the selected file at app startup.

Env Preferences

Use this skill when you are setting up environment-variable conventions for a new project or runtime entrypoint.

Standard Pattern

1. Commit template.env with placeholders and comments.
2. Keep dev.env, test.env, and prod.env local-only (never committed).
3. Select runtime environment with APP_ENV=dev|test|prod (default: dev).
4. App startup should load <APP_ENV>.env, validate required keys, and fail with a clear error if the file is missing.

Required .gitignore Entries

dev.env
test.env
prod.env
**/dev.env
**/test.env
**/prod.env

Startup Pattern (Python)

import os
from pathlib import Path
from dotenv import load_dotenv

valid = {"dev", "test", "prod"}
app_env = os.getenv("APP_ENV", "dev").strip().lower()
if app_env not in valid:
    raise ValueError(f"Invalid APP_ENV '{app_env}'")

env_path = Path(__file__).parent / f"{app_env}.env"
if not env_path.exists():
    raise FileNotFoundError(f"Missing {env_path}; copy template.env first")

load_dotenv(env_path)

Documentation Checklist

• README setup tells users to copy template.env into dev.env/test.env/prod.env.
• README run section includes APP_ENV=test ... and APP_ENV=prod ... examples.
• Startup script docstring explains the APP_ENV loading behavior.