Configuration

Fenrir provides a Flask-style configuration system with a dict-based Config class.

Application Configuration

from fenrir import Fenrir

app = Fenrir(
    title="My Application",
    version="4.1.2",
    docs_url="/docs",
    redoc_url="/redoc",
    openapi_url="/openapi.json"
)

Environment-Based Configuration

import os
from fenrir import Fenrir

debug = os.getenv("DEBUG", "False") == "True"
app = Fenrir()
app.debug = debug

Config Class

Config is a dict subclass that provides methods for loading configuration from various sources.

class Config(dict):
    def __init__(self, root_path: str, defaults: dict = None):
        ...

root_path: Base directory for resolving relative file paths used by from_pyfile() and from_envvar().
defaults: Optional dict of initial config values.

Loading Configuration

`from_object(obj)`

Load uppercase attributes from an object or a module path string.

class Config:
    DEBUG = True
    TESTING = False
    DATABASE_URL = "postgresql://localhost/mydb"
    SECRET_KEY = "your-secret-key"

app.config.from_object(Config)

String form imports the module dynamically:

app.config.from_object("myapp.config.ProductionConfig")

`from_mapping(mapping)`

Load uppercase keys from any Mapping or dict.

app.config.from_mapping({
    "DEBUG": True,
    "SECRET_KEY": "your-secret-key",
    "DATABASE_URL": "postgresql://localhost/mydb",
})

`from_pyfile(filename, silent=False)`

Execute a Python file and load its uppercase attributes. The file is evaluated in an isolated module namespace.

filename: Path to the Python file, resolved relative to root_path.
silent: If True, return False on failure instead of raising OSError.

app.config.from_pyfile("config.py", silent=True)

Example config.py:

DEBUG = True
SECRET_KEY = "dev-key"
DATABASE_URL = "sqlite:///app.db"

`from_envvar(variable_name, silent=False)`

Read a file path from an environment variable and call from_pyfile() on it.

variable_name: Name of the environment variable containing the config file path.
silent: If True, return False on failure instead of raising RuntimeError.

export APP_CONFIG="/etc/myapp/config.py"

app.config.from_envvar("APP_CONFIG", silent=True)

Custom Configuration

app = Fenrir()

# Set config values directly
app.config["DEBUG"] = True
app.config["TESTING"] = False
app.config["DATABASE_URL"] = "postgresql://localhost/mydb"
app.config["SECRET_KEY"] = "your-secret-key"

# Load from an object
class Config:
    DEBUG = True
    TESTING = False
    DATABASE_URL = "postgresql://localhost/mydb"
    SECRET_KEY = "your-secret-key"

app.config.from_object(Config)

# Load from a mapping
app.config.from_mapping({
    "DEBUG": True,
    "SECRET_KEY": "your-secret-key",
})

# Load from a Python file
app.config.from_pyfile("config.py", silent=True)

# Load from an environment variable pointing to a config file
app.config.from_envvar("APP_CONFIG_FILE", silent=True)

Config API Reference

Constructor

Config(root_path, defaults=None)

root_path (str): Base path for resolving relative file paths.
defaults (dict, optional): Initial config values.

Methods

Method	Description
`from_object(obj)`	Load uppercase attributes from an object or module string.
`from_mapping(mapping)`	Load uppercase keys from a `Mapping` or `dict`.
`from_pyfile(filename, silent=False)`	Load config by executing a Python file. Returns `True` on success.
`from_envvar(variable_name, silent=False)`	Load config from the file path in an env var. Returns `True` on success.
`get(key, default=None)`	Get a config value (inherited from `dict`).

Attributes

Attribute	Type	Description
`root_path`	`str`	Base directory for file operations.

Default Configuration Values

These defaults are set when a Fenrir application is created:

Key	Default	Description
`ENV`	`"production"`	Application environment name.
`DEBUG`	`False`	Enable debug mode.
`TESTING`	`False`	Enable testing mode.
`SECRET_KEY`	`None`	Secret key for signing sessions and tokens.
`SESSION_COOKIE_NAME`	`"session"`	Name of the session cookie.
`SESSION_COOKIE_DOMAIN`	`None`	Domain scope for the session cookie.
`SESSION_COOKIE_PATH`	`"/"`	Path scope for the session cookie.
`SESSION_COOKIE_HTTPONLY`	`True`	Restrict cookie to HTTP-only access.
`SESSION_COOKIE_SECURE`	`True`	Require HTTPS for the session cookie.
`SESSION_COOKIE_SAMESITE`	`None`	SameSite attribute for the session cookie.

App Attributes

app.debug                    # bool — debug mode
app.strict_content_type      # bool — require JSON content-type
app.title                    # str — app title
app.version                  # str — app version
app.template_folder          # str — template directory
app.json                     # JSONProvider — JSON serializer
app.renderer                 # BaseTemplateRenderer — template renderer
app.session_interface        # SessionInterface — session backend
app.config                   # Config — configuration object