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"""Application initialisation module."""
import os
import sys
import logging
from pathlib import Path
from typing import Optional, Callable
from flask import Flask
from flask_cors import CORS
from authlib.jose import JsonWebKey
from gn_auth import hooks
from gn_auth.misc_views import misc
from gn_auth.auth.views import oauth2
from gn_auth.auth.authentication.oauth2.server import setup_oauth2_server
from . import settings
from .errors import register_error_handlers
class ConfigurationError(Exception):
"""Raised in case of a configuration error."""
def check_mandatory_settings(app: Flask) -> None:
"""Verify that mandatory settings are defined in the application"""
undefined = tuple(
setting for setting in (
"SECRET_KEY", "SQL_URI", "AUTH_DB", "AUTH_MIGRATIONS",
"OAUTH2_SCOPES_SUPPORTED")
if not ((setting in app.config) and bool(app.config[setting])))
if len(undefined) > 0:
raise ConfigurationError(
"You must provide (valid) values for the following settings: " +
"\n\t* " + "\n\t* ".join(undefined))
def override_settings_with_envvars(
app: Flask, ignore: tuple[str, ...]=tuple()) -> None:
"""Override settings in `app` with those in ENVVARS"""
for setting in (key for key in app.config if key not in ignore):
app.config[setting] = os.environ.get(setting) or app.config[setting]
def load_secrets_conf(app: Flask) -> None:
"""Load the secrets file."""
secretsfile = app.config.get("GN_AUTH_SECRETS")
if ((not secretsfile is None) and (bool(secretsfile.strip()))):
secretsfile = Path(secretsfile.strip()).absolute()
app.config["GN_AUTH_SECRETS"] = secretsfile
if not secretsfile.exists():
raise ConfigurationError(
f"The file '{secretsfile}' does not exist. "
"You must provide a path to an existing secrets file.")
app.config.from_pyfile(secretsfile)
def dev_loggers(appl: Flask) -> None:
"""Setup the logging handlers."""
stderr_handler = logging.StreamHandler(stream=sys.stderr)
appl.logger.addHandler(stderr_handler)
root_logger = logging.getLogger()
root_logger.addHandler(stderr_handler)
root_logger.setLevel(appl.config["LOGLEVEL"])
def gunicorn_loggers(appl: Flask) -> None:
"""Use gunicorn logging handlers for the application."""
logger = logging.getLogger("gunicorn.error")
appl.logger.handlers = logger.handlers
appl.logger.setLevel(logger.level)
def setup_logging(appl: Flask) -> Callable[[Flask], None]:
"""
Setup the loggers according to the WSGI server used to run the application.
"""
# https://datatracker.ietf.org/doc/html/draft-coar-cgi-v11-03#section-4.1.17
# https://wsgi.readthedocs.io/en/latest/proposals-2.0.html#making-some-keys-required
# https://peps.python.org/pep-3333/#id4
software, *_version_and_comments = os.environ.get(
"SERVER_SOFTWARE", "").split('/')
if bool(software):
return gunicorn_loggers(appl)
return dev_loggers(appl)
def create_app(config: Optional[dict] = None) -> Flask:
"""Create and return a new flask application."""
app = Flask(__name__)
# ====== Setup configuration ======
app.config.from_object(settings) # Default settings
# Override defaults with startup settings
app.config.update(config or {})
# Override app settings with site-local settings
if "GN_AUTH_CONF" in os.environ:
app.config.from_envvar("GN_AUTH_CONF")
override_settings_with_envvars(app)
load_secrets_conf(app)
# ====== END: Setup configuration ======
setup_logging(app)
check_mandatory_settings(app)
setup_oauth2_server(app)
CORS(
app,
origins=app.config["CORS_ORIGINS"],
allow_headers=app.config["CORS_HEADERS"],
supports_credentials=True, intercept_exceptions=False)
## Blueprints
app.register_blueprint(misc, url_prefix="/")
app.register_blueprint(oauth2, url_prefix="/auth")
register_error_handlers(app)
hooks.register_hooks(app)
return app
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