Settings from the environment in Python

One model for configuration, read from the environment with defaults.

import os

from pydantic import BaseModel, Field


class Settings(BaseModel):
    port: int = 8080
    debug: bool = False
    theme: str = "default"
    languages: int = Field(default=10, ge=1)

    @classmethod
    def from_env(cls, prefix="TYPESTAR_"):
        raw = {key[len(prefix):].lower(): value
               for key, value in os.environ.items() if key.startswith(prefix)}
        return cls.model_validate(raw)


os.environ["TYPESTAR_PORT"] = "9000"
os.environ["TYPESTAR_DEBUG"] = "true"
settings = Settings.from_env()
print(settings.port, settings.debug, settings.theme)

How it works

1. Annotations give every setting a type and a default.
2. model_validate accepts a dict of raw strings.
3. Coercion means the rest of the program sees real types.

Keywords and builtins used here

• Settings
• bool
• class
• cls
• def
• for
• from_env
• if
• int
• len
• print
• return
• str

The run, in numbers

Lines

22

Characters to type

527

Tokens

147

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 84 seconds.

Type this snippet

Step 5 of 5 in Pydantic models, step 5 of 19 in Web services & data access.

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