wsgi.py

#!/usr/bin/env python3

from __future__ import unicode_literals

import logging
import multiprocessing
import os
import sys
from argparse import ArgumentParser
from typing import Dict

import gunicorn.app.base
from flask import Flask
from gunicorn.six import iteritems

from shop_db2.api import app, set_app

import configuration as config  # isort: skip


def number_of_workers() -> int:
    return (multiprocessing.cpu_count() * 2) + 1


class StandaloneApplication(gunicorn.app.base.BaseApplication):
    def __init__(self, _app: Flask, _options: Dict = None) -> None:
        self.options = _options or {}
        self.application = _app
        super(StandaloneApplication, self).__init__()

    def load_config(self) -> None:
        _config = dict(
            [(key, value) for key, value in iteritems(self.options) if key in self.cfg.settings and value is not None]
        )
        for key, value in iteritems(_config):
            self.cfg.set(key.lower(), value)

    def load(self) -> Flask:
        return self.application


if __name__ == "__main__":
    # Check whether the productive database exists.
    if not os.path.isfile(config.ProductiveConfig.DATABASE_PATH):
        sys.exit(
            "No database found. Please read the documentation and use " "the setupdb.py script to initialize shop-db."
        )

    parser = ArgumentParser(description="Starting shop-db2 with a gunicorn server")
    parser.add_argument(
        "--loglevel",
        help="select the log level",
        default="WARNING",
        choices=["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"],
    )

    args = parser.parse_args()

    # Overwrite the app configuration with the productive settings.
    set_app(config.ProductiveConfig)

    # Logging
    app.logger.handlers = logging.getLogger("gunicorn.error").handlers
    app.logger.setLevel(logging.getLevelName(args.loglevel))

    # Set the gunicorn options.
    options = {
        "bind": "%s:%s" % (app.config["HOST"], app.config["PORT"]),
        # BEGIN OF WARNING
        # DO NOT CHANGE THIS VALUE, THE APPLICATION IS NOT DESIGNED FOR
        # MULTITHREADING AND ERRORS MAY OCCUR IN THE DATABASE!!!
        "workers": 1,
        # END WARNING
    }

    StandaloneApplication(app, options).run()