Sillo Configuration System

Config class, .env loading, secret masking, environment variables

1. Config Base Class

Source: core/sillo/config/core.py

Config is the base class for all Sillo configuration. It extends Pydantic’s BaseModel with automatic .env file loading, environment variable mapping, and secret masking in repr output.

The .env reading is Sillo’s own — sillo.env, documented in Environment & .env. python-dotenv is not a dependency of the framework and is not imported anywhere in it.

Class Definition

class Config(BaseModel):
    """Base configuration class, loaded from the environment."""

    model_config = ConfigDict(extra="ignore")

    def __init__(
        self,
        _env_file: str | None = _UNSET,
        _case_sensitive: bool = _UNSET,
        _env_prefix: str = _UNSET,
        **data
    ):

_UNSET is a sentinel, not a default value: it separates “the subclass said nothing”, which loads the project’s .env, from an explicit None, which loads no file at all.

Features

Feature	Description
`.env` loading	Finds and loads the project’s `.env` through `sillo.env.autoload`, once per process. No third-party dependency
Env prefix	`env_prefix` maps a whole class onto `PREFIX_*` variables
Type validation	All fields are validated by Pydantic at construction time
Env var mapping	Field names are mapped to uppercase environment variables by default
Secret masking	Fields with names containing `secret`, `key`, `password`, `token`, etc. are masked in `repr()`
IDE autocomplete	Full type hints for all fields
Extra field ignore	`extra="ignore"` prevents crashes from unknown environment variables

Initialization Flow

def __init__(self, _env_file=_UNSET, _case_sensitive=_UNSET, _env_prefix=_UNSET, **data):
    # 1. Read the subclass's inner options class (Env, or the older Config)
    options = self._options()
    env_file = _env_file if _env_file is not _UNSET else options.get("env_file", _UNSET)
    case_sensitive = ...
    prefix = ...

    # 2. Load the file: the project's .env when nothing was asked for,
    #    the named file when one was, nothing at all when it is None.
    if env_file is _UNSET:
        autoload()
    elif env_file is not None:
        load_env(env_file)

    # 3. Map fields onto environment variables, alias first
    env_data = {}
    for name, field in self.__class__.model_fields.items():
        alias = field.alias if isinstance(field.alias, str) else None
        for candidate in (alias, name):
            if candidate is None:
                continue
            key = prefix + candidate
            if not case_sensitive:
                key = key.upper()
            if key in os.environ:
                env_data[alias or name] = os.environ[key]
                break

    # 4. Merge with provided data (provided data takes precedence)
    env_data.update(data)
    super().__init__(**env_data)

Three sources, most specific first: arguments beat the real environment, and the real environment beats the file.

Environment Variable Mapping

class AppConfig(Config):
    database_url: str
    debug: bool = False

# Maps to:
#   database_url → DATABASE_URL (env var)
#   debug → DEBUG (env var)

config = AppConfig()  # Reads DATABASE_URL and DEBUG from environment
config = AppConfig(database_url="sqlite:///app.db")  # Explicit values take precedence

Secret Masking

def __repr__(self) -> str:
    fields_repr = {}
    for field_name, field_value in self.model_dump().items():
        if self._is_secret_field(field_name):
            fields_repr[field_name] = "***"
        else:
            fields_repr[field_name] = field_value
    return f"<{self.__class__.__name__} {fields_repr}>"

@staticmethod
def _is_secret_field(field_name: str) -> bool:
    secret_keywords = (
        "secret", "key", "password", "token", "apikey", "api_key",
        "auth", "credential", "private",
    )
    return any(keyword in field_name.lower() for keyword in secret_keywords)

Example:

class AppConfig(Config):
    database_url: str
    jwt_secret: str
    api_key: str

config = AppConfig(
    database_url="postgres://localhost/mydb",
    jwt_secret="super-secret",
    api_key="sk-123"
)
print(repr(config))
# <AppConfig {'database_url': 'postgres://localhost/mydb', 'jwt_secret': '***', 'api_key': '***'}>

Subclass Options Inner Class

class AppConfig(Config):
    database_url: str
    debug: bool = False

    class Env:
        env_file = ".env"          # None loads no file
        env_prefix = ""
        case_sensitive = False

Env is checked first, then Config — the name earlier versions documented, kept working but no longer recommended, since Pydantic uses it for its own deprecated class-based settings and warns whenever it sees one.

Each setting can be overridden at instantiation time:

config = AppConfig(_env_file=".env.production", _case_sensitive=True, _env_prefix="APP_")

Re-exported Field

from pydantic import Field as PydanticField
Field = PydanticField

Field is re-exported from Pydantic for convenience, so users can import from sillo.config:

from sillo.config import Config, Field

class AppConfig(Config):
    name: str = Field(default="Sillo", description="Application name")

2. DatabaseConfig

Pattern: Each subsystem owns its configuration class, extending Config.

Example Structure

from sillo.config import Config, Field
from typing import Literal

class DatabaseConfig(Config):
    """Database connection configuration."""

    # Connection
    url: str = Field(description="Database connection URL")
    pool_size: int = Field(default=10, description="Connection pool size")
    max_overflow: int = Field(default=20, description="Max overflow connections")
    pool_timeout: int = Field(default=30, description="Pool checkout timeout (seconds)")
    pool_recycle: int = Field(default=3600, description="Connection recycle time (seconds)")

    # Behavior
    echo: bool = Field(default=False, description="Log all SQL statements")
    echo_pool: bool = Field(default=False, description="Log pool checkouts/checkins")
    autoflush: bool = Field(default=True, description="Autoflush after each statement")
    autocommit: bool = Field(default=False, description="Autocommit mode")

    # Migration
    migration_dir: str = Field(default="migrations", description="Migration scripts directory")

    class Env:
        env_prefix = "DATABASE_"

Environment Variable Mapping

DATABASE_URL=postgres://user:pass@localhost:5432/mydb
DATABASE_POOL_SIZE=20
DATABASE_MAX_OVERFLOW=30
DATABASE_ECHO=false
DATABASE_MIGRATION_DIR=./migrations

Usage

db_config = DatabaseConfig()
# or
db_config = DatabaseConfig(url="sqlite:///app.db", pool_size=5)

3. SessionConfig

Example Structure

class SessionConfig(Config):
    """Session management configuration."""

    # Storage
    driver: Literal["cookie", "file", "redis", "database"] = Field(
        default="cookie", description="Session storage driver"
    )
    lifetime: int = Field(default=120, description="Session lifetime in minutes")
    encrypt: bool = Field(default=True, description="Encrypt session data")

    # Cookie settings (when driver="cookie")
    cookie_name: str = Field(default="sillo_session", description="Session cookie name")
    cookie_domain: str | None = Field(default=None, description="Cookie domain")
    cookie_path: str = Field(default="/", description="Cookie path")
    cookie_secure: bool = Field(default=False, description="Require HTTPS for cookie")
    cookie_httponly: bool = Field(default=True, description="HttpOnly flag")
    cookie_samesite: Literal["lax", "strict", "none"] = Field(
        default="lax", description="SameSite attribute"
    )

    # Redis settings (when driver="redis")
    redis_url: str | None = Field(default=None, description="Redis connection URL")

    # Database settings (when driver="database")
    table_name: str = Field(default="sessions", description="Sessions table name")

    class Env:
        env_prefix = "SESSION_"

Environment Variable Mapping

SESSION_DRIVER=redis
SESSION_LIFETIME=60
SESSION_ENCRYPT=true
SESSION_COOKIE_NAME=my_session
SESSION_COOKIE_SECURE=true
SESSION_REDIS_URL=redis://localhost:6379/0

4. MailConfig

Example Structure

class MailConfig(Config):
    """Email sending configuration."""

    # SMTP settings
    host: str = Field(default="localhost", description="SMTP server host")
    port: int = Field(default=587, description="SMTP server port")
    username: str | None = Field(default=None, description="SMTP username")
    password: str | None = Field(default=None, description="SMTP password")
    use_tls: bool = Field(default=True, description="Use STARTTLS")
    use_ssl: bool = Field(default=False, description="Use SSL/TLS")

    # Sender defaults
    from_address: str = Field(default="noreply@example.com", description="Default sender address")
    from_name: str = Field(default="Sillo App", description="Default sender name")

    # Queue
    queue_enabled: bool = Field(default=False, description="Enable mail queue")
    retry_count: int = Field(default=3, description="Retry count for failed sends")
    retry_delay: int = Field(default=60, description="Retry delay in seconds")

    class Env:
        env_prefix = "MAIL_"

Environment Variable Mapping

MAIL_HOST=smtp.gmail.com
MAIL_PORT=587
MAIL_USERNAME=user@gmail.com
MAIL_PASSWORD=app-specific-password
MAIL_USE_TLS=true
MAIL_FROM_ADDRESS=noreply@myapp.com

5. CorsConfig

Example Structure

class CorsConfig(Config):
    """CORS (Cross-Origin Resource Sharing) configuration."""

    allow_origins: list[str] = Field(
        default=["*"],
        description="Allowed origins. Use ['*'] for all origins."
    )
    allow_methods: list[str] = Field(
        default=["GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"],
        description="Allowed HTTP methods"
    )
    allow_headers: list[str] = Field(
        default=["*"],
        description="Allowed ctx headers"
    )
    allow_credentials: bool = Field(
        default=False,
        description="Allow credentials (cookies, auth headers)"
    )
    expose_headers: list[str] = Field(
        default=[],
        description="Headers exposed to the browser"
    )
    max_age: int = Field(
        default=600,
        description="Preflight cache duration in seconds"
    )

    class Env:
        env_prefix = "CORS_"

Environment Variable Mapping

CORS_ALLOW_ORIGINS=http://localhost:3000,https://myapp.com
CORS_ALLOW_METHODS=GET,POST,PUT,DELETE
CORS_ALLOW_CREDENTIALS=true
CORS_MAX_AGE=86400

Usage with Middleware

from sillo.middleware.security import CORSMiddleware

cors_config = CorsConfig(
    allow_origins=["http://localhost:3000"],
    allow_credentials=True,
)

app.use(CORSMiddleware(
    allow_origins=cors_config.allow_origins,
    allow_methods=cors_config.allow_methods,
    allow_headers=cors_config.allow_headers,
    allow_credentials=cors_config.allow_credentials,
    max_age=cors_config.max_age,
))

6. CSRFConfig

Example Structure

from sillo import HttpContext

class CSRFConfig(Config):
    """CSRF (Cross-Site HttpContext Forgery) protection configuration."""

    enabled: bool = Field(default=True, description="Enable CSRF protection")
    secret: str = Field(description="Secret key for CSRF token generation")
    token_name: str = Field(default="_token", description="Form field name for token")
    header_name: str = Field(default="X-CSRF-Token", description="Header name for token")
    cookie_name: str = Field(default="csrf_token", description="Cookie name for token")
    lifetime: int = Field(default=3600, description="Token lifetime in seconds")
    secure: bool = Field(default=False, description="Require HTTPS for cookie")
    same_site: Literal["lax", "strict", "none"] = Field(
        default="lax", description="SameSite attribute"
    )
    exempt_methods: list[str] = Field(
        default=["GET", "HEAD", "OPTIONS"],
        description="Methods exempt from CSRF checks"
    )
    exempt_paths: list[str] = Field(
        default=[],
        description="Paths exempt from CSRF checks"
    )

    class Env:
        env_prefix = "CSRF_"

Environment Variable Mapping

CSRF_ENABLED=true
CSRF_SECRET=my-csrf-secret-key
CSRF_TOKEN_NAME=_token
CSRF_HEADER_NAME=X-CSRF-Token
CSRF_LIFETIME=3600

7. RateLimitConfig

Example Structure

class RateLimitConfig(Config):
    """Rate limiting configuration."""

    enabled: bool = Field(default=True, description="Enable rate limiting")
    driver: Literal["memory", "redis", "database"] = Field(
        default="memory", description="Rate limit storage driver"
    )

    # Default limits
    default_rate: str = Field(
        default="60/minute",
        description="Default rate limit (format: count/period)"
    )
    default_burst: int = Field(
        default=10,
        description="Default burst allowance"
    )

    # Redis settings
    redis_url: str | None = Field(default=None, description="Redis URL for rate limiting")

    # BaseResponse
    retry_after_header: bool = Field(
        default=True,
        description="Include Retry-After header in 429 responses"
    )
    message: str = Field(
        default="Rate limit exceeded. Please try again later.",
        description="Error message for rate limited requests"
    )

    class Env:
        env_prefix = "RATE_LIMIT_"

Environment Variable Mapping

RATE_LIMIT_ENABLED=true
RATE_LIMIT_DRIVER=redis
RATE_LIMIT_DEFAULT_RATE=100/minute
RATE_LIMIT_DEFAULT_BURST=20
RATE_LIMIT_REDIS_URL=redis://localhost:6379/1

Period Parsing

The default_rate string is parsed into count and period:

"60/minute"  → 60 requests per 60 seconds
"1000/hour"  → 1000 requests per 3600 seconds
"10/second"  → 10 requests per 1 second
"5000/day"   → 5000 requests per 86400 seconds

8. InertiaConfig

Example Structure

class InertiaConfig(Config):
    """Inertia.js integration configuration."""

    # Version management
    version: str | None = Field(
        default=None,
        description="Asset version for cache busting"
    )

    # Root template
    root_view: str = Field(
        default="app.html",
        description="Root HTML template that wraps Inertia responses"
    )

    # SSR (Server-Side Rendering)
    ssr_enabled: bool = Field(default=False, description="Enable SSR mode")
    ssr_url: str | None = Field(
        default=None,
        description="SSR server URL (e.g., http://localhost:13714)"
    )

    # History encryption
    encrypt_history: bool = Field(
        default=False,
        description="Encrypt back/forward history state"
    )

    # Testing
    testing_enabled: bool = Field(
        default=False,
        description="Enable Inertia testing helpers"
    )

    class Env:
        env_prefix = "INERTIA_"

Environment Variable Mapping

INERTIA_VERSION=abc123
INERTIA_ROOT_VIEW=app.html
INERTIA_SSR_ENABLED=true
INERTIA_SSR_URL=http://localhost:13714
INERTIA_ENCRYPT_HISTORY=true

Inertia Integration Pattern

from inertia import InertiaConfig, inertia_middleware

config = InertiaConfig(
    version="1.0.0",
    root_view="app.html",
)

# Inertia middleware uses config to:
# 1. Compare X-Inertia-Version header with config.version
# 2. Force a full page reload on version mismatch
# 3. Render the root template with the Inertia page object

9. Configuration Patterns

10.1 Composite Configuration

Applications typically create a top-level config that composes subsystem configs:

from sillo.config import Config, Field

class AppConfig(Config):
    # Application
    app_name: str = Field(default="My App")
    debug: bool = Field(default=False)
    secret_key: str = Field(description="Application secret key")

    # Subsystem configs are declared as fields
    # They can be nested or flattened depending on preference

    class Env:
        env_file = ".env"

# Flat approach (all vars at top level)
class FlatAppConfig(Config):
    debug: bool = False
    database_url: str = ""
    session_driver: str = "cookie"
    mail_host: str = "localhost"
    cors_allow_origins: str = "*"

10.2 Environment-Specific Configuration

import os

class AppConfig(Config):
    debug: bool = False
    database_url: str = ""
    log_level: str = "info"

# Load from environment-specific .env file
env = os.getenv("APP_ENV", "development")
config = AppConfig(_env_file=f".env.{env}")
# .env.development, .env.staging, .env.production

10.3 Validation with Pydantic

from pydantic import field_validator
from sillo.config import Config

class DatabaseConfig(Config):
    url: str
    pool_size: int = 10

    @field_validator("url")
    @classmethod
    def validate_url(cls, v):
        if not v.startswith(("postgres://", "mysql://", "sqlite://")):
            raise ValueError("Unsupported database URL scheme")
        return v

    @field_validator("pool_size")
    @classmethod
    def validate_pool_size(cls, v):
        if v < 1 or v > 100:
            raise ValueError("Pool size must be between 1 and 100")
        return v

10.4 Integration with SilloApp

from sillo import SilloApp
from sillo.config import Config

class AppConfig(Config):
    debug: bool = False
    title: str = "My API"
    version: str = "1.0.0"

config = AppConfig()

app = SilloApp(
    debug=config.debug,
    title=config.title,
    version=config.version,
)

10.5 Configuration Loading Priority

The loading priority for configuration values is:

Constructor arguments (highest priority)
Environment variables
.env file values
Field defaults (lowest priority)

# .env file contains: DEBUG=true
# Environment variable: DEBUG=false

config = AppConfig()                    # DEBUG=False (env var wins)
config = AppConfig(_env_file=".env")    # DEBUG=False (env var still wins)
config = AppConfig(debug=True)          # DEBUG=True (constructor arg wins)

10.6 Secret Management

Configuration fields with secret-related names are automatically masked:

class AppConfig(Config):
    database_url: str          # Not masked
    app_name: str              # Not masked
    jwt_secret: str            # Masked (contains "secret")
    api_key: str               # Masked (contains "key")
    smtp_password: str         # Masked (contains "password")
    stripe_token: str          # Masked (contains "token")
    auth_token: str            # Masked (contains "auth" and "token")
    private_key: str           # Masked (contains "private")
    credentials: str           # Masked (contains "credential")

The masking applies to repr() output only. The actual values are accessible via attribute access:

config = AppConfig(jwt_secret="super-secret")
print(repr(config))        # <AppConfig {'jwt_secret': '***'}>
print(config.jwt_secret)   # "super-secret"

Appendix: Config Class Hierarchy

graph TD
    BM["pydantic.BaseModel"] --> CFG["Config"]
    CFG --> DBC["DatabaseConfig"]
    CFG --> SC["SessionConfig"]
    CFG --> MC["MailConfig"]
    CFG --> CC["CorsConfig"]
    CFG --> CSRF["CSRFConfig"]
    CFG --> RLC["RateLimitConfig"]
    CFG --> IC["InertiaConfig"]
    CFG --> APP_CFG["AppConfig (user-defined)"]

Module Structure

core/sillo/config/
├── __init__.py          # Re-exports Config, Field
└── core.py              # Config base class, Field re-export

Public API

from sillo.config import Config, Field

__all__ = ["Config", "Field"]

The Field export is Pydantic’s Field function, re-exported for convenience:

from pydantic import Field as PydanticField
Field = PydanticField

Extension Points

Each subsystem can define its own Config subclass:

# In sillo/session/config.py (if it exists)
from sillo.config import Config, Field

class SessionConfig(Config):
    driver: str = "cookie"
    lifetime: int = 120
    # ...

# In sillo/mail/config.py (if it exists)
from sillo.config import Config, Field

class MailConfig(Config):
    host: str = "localhost"
    port: int = 587
    # ...

The pattern is consistent: every subsystem’s config extends Config, gets .env loading for free, and masks secrets automatically.

Sillo Configuration System

1. Config Base Class

Class Definition

Features

Initialization Flow

Environment Variable Mapping

Secret Masking

Subclass Options Inner Class

Re-exported Field

2. DatabaseConfig

Example Structure

Environment Variable Mapping

Usage

3. SessionConfig

Example Structure

Environment Variable Mapping

4. MailConfig

Example Structure

Environment Variable Mapping

5. CorsConfig

Example Structure

Environment Variable Mapping

Usage with Middleware

6. CSRFConfig

Example Structure

Environment Variable Mapping

7. RateLimitConfig

Example Structure

Environment Variable Mapping

Period Parsing

8. InertiaConfig

Example Structure

Environment Variable Mapping

Inertia Integration Pattern

9. Configuration Patterns

10.1 Composite Configuration

10.2 Environment-Specific Configuration

10.3 Validation with Pydantic

10.4 Integration with SilloApp

10.5 Configuration Loading Priority

10.6 Secret Management

Appendix: Config Class Hierarchy

Module Structure

Public API

Extension Points

Internal Reference

Architecture & Foundations

HTTP Layer

Dependency Injection & Validation

Authentication & Authorization

Security

Database & ORM

Background Work

Real-Time

Application Features

Testing & Tools

Ecosystem Packages

Cross-Cutting Concerns