tmpl-fastapi/app/common.py

import secrets
from pathlib import Path

from fastapi.templating import Jinja2Templates
from pydantic import BaseSettings


# Directories
file_dir = Path(__file__).parent
templates_dir = str(file_dir.parent / 'templates')
static_dir = str(file_dir.parent / 'static')


# Main configuration
class Settings(BaseSettings):
    debug: bool = False
    secret_key: str = 'secret'
    app_host: str = '127.0.0.1'
    app_port: int = 8000


# Instantiate Settings class
settings = Settings()

# Jinja templates handler
templates = Jinja2Templates(
    directory=templates_dir,
)


def secret_key_check() -> None:
    """Generates a secret key automatically
    if the env var `secret_key` is not set
    or contains text `secret`"""

    if settings.secret_key == 'secret':

        key_file = Path('/tmp/secret_key')

        if key_file.exists():
            with key_file.open('rt') as f:
                secret_key = f.read()

        else:
            secret_key = secrets.token_hex(32)
            with key_file.open('wt') as f:
                f.write(secret_key)

        settings.secret_key = secret_key


# Call the function
secret_key_check()