001
from pathlib import Path
002
from typing import Literal
003

004
from pydantic import (
005
    BaseModel,
006
    ConfigDict,
007
    Field,
008
    HttpUrl,
009
    SecretStr,
010
    model_validator,
011
)
012
from pydantic_settings import (
013
    BaseSettings,
014
    PydanticBaseSettingsSource,
015
    SettingsConfigDict,
016
    TomlConfigSettingsSource,
017
)
018

019
PROJECT_ROOT = Path(__file__).resolve().parents[2]
020

021

022
class StrictSettingsModel(BaseModel):
023
    model_config = ConfigDict(
024
        extra="forbid",
025
        hide_input_in_errors=True,
026
    )
027

028

029
class AppSettings(StrictSettingsModel):
030
    name: str = Field(min_length=1)
031
    environment: Literal["development", "test", "staging", "production"]
032
    log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]
033

034

035
class CorsSettings(StrictSettingsModel):
036
    allow_origins: list[str]
037
    allow_methods: list[str]
038

039

040
class ServerSettings(StrictSettingsModel):
041
    host: str = Field(min_length=1)
042
    port: int = Field(ge=1, le=65535)
043
    cors: CorsSettings
044

045

046
class ModelSettings(StrictSettingsModel):
047
    provider: str = Field(min_length=1)
048
    name: str = Field(min_length=1)
049
    base_url: HttpUrl
050
    api_key: SecretStr | None = None
051
    temperature: float = Field(ge=0, le=2)
052
    timeout_seconds: float = Field(gt=0)
053
    max_retries: int = Field(ge=0, le=10)
054

055

056
class LangGraphSettings(StrictSettingsModel):
057
    recursion_limit: int = Field(gt=0)
058
    checkpoint_backend: Literal["memory", "postgres"]
059

060

061
class DatabaseSettings(StrictSettingsModel):
062
    url: SecretStr | None = None
063
    pool_size: int = Field(gt=0)
064
    pool_timeout_seconds: float = Field(gt=0)
065

066

067
class Settings(BaseSettings):
068
    app: AppSettings
069
    server: ServerSettings
070
    model: ModelSettings
071
    langgraph: LangGraphSettings
072
    database: DatabaseSettings
073
    langsmith_tracing: bool = False
074
    langsmith_api_key: SecretStr | None = None
075

076
    model_config = SettingsConfigDict(
077
        env_file=PROJECT_ROOT / ".env",
078
        env_file_encoding="utf-8",
079
        env_ignore_empty=True,
080
        env_nested_delimiter="__",
081
        toml_file=PROJECT_ROOT / "config.toml",
082
        extra="forbid",
083
        hide_input_in_errors=True,
084
    )
085

086
    @classmethod
087
    def settings_customise_sources(
088
        cls,
089
        settings_cls: type[BaseSettings],
090
        init_settings: PydanticBaseSettingsSource,
091
        env_settings: PydanticBaseSettingsSource,
092
        dotenv_settings: PydanticBaseSettingsSource,
093
        file_secret_settings: PydanticBaseSettingsSource,
094
    ) -> tuple[PydanticBaseSettingsSource, ...]:
095
        return (
096
            init_settings,
097
            env_settings,
098
            dotenv_settings,
099
            TomlConfigSettingsSource(settings_cls),
100
        )
101

102
    @model_validator(mode="after")
103
    def validate_runtime(self) -> "Settings":
104
        if self.langsmith_tracing and self.langsmith_api_key is None:
105
            raise ValueError("启用 LangSmith 追踪时必须配置 API Key")
106

107
        if self.app.environment == "production":
108
            if self.model.api_key is None:
109
                raise ValueError("生产环境必须配置模型 API Key")
110
            if self.model.base_url.host in {"localhost", "127.0.0.1"}:
111
                raise ValueError("生产模型地址不能使用本机地址")
112

113
        return self

1
settings = Settings()
2

3
print(settings.app.environment)
4
print(settings.model.name)
5
print(settings.model.timeout_seconds)

1
default = {
2
    "model": {"name": "deepseek-v4-flash", "timeout": 30},
3
}
4
production = {
5
    "model": {"timeout": 60},
6
}
7

8
default.update(production)
9
# model.name 也被一起丢失了

1
model_config = SettingsConfigDict(
2
    toml_file=[
3
        PROJECT_ROOT / "config" / "default.toml",
4
        PROJECT_ROOT / "config" / "production.toml",
5
    ],
6
)
7

8
# settings_customise_sources() 中
9
toml_settings = TomlConfigSettingsSource(settings_cls, deep_merge=True)

01
ALLOWED_ENVIRONMENTS = {
02
    "development",
03
    "test",
04
    "staging",
05
    "production",
06
}
07

08

09
def validate_environment(value: str) -> str:
10
    if value not in ALLOWED_ENVIRONMENTS:
11
        raise ValueError(f"不支持的运行环境：{value}")
12
    return value

1
from pydantic import SecretStr
2

3

4
class ModelSettings(StrictSettingsModel):
5
    api_key: SecretStr

1
if settings.model.api_key is None:
2
    raise RuntimeError("尚未配置模型 API Key")
3

4
api_key = settings.model.api_key.get_secret_value()