Postgress Connection Pool with Gunicorn and Connexion

wsgi.py

#!/usr/bin/env python3
import configparser, os
import connexion
from swagger_server import encoder
from flask_cors import CORS
from flask import g, jsonify
import psycopg2
from psycopg2 import pool


application = connexion.App(__name__, specification_dir='./swagger/')
CORS(application.app)
application.app.json_encoder = encoder.JSONEncoder
application.add_api('swagger.yaml', arguments={'title': 'My Simple Swagger API'})

# CREATE A DB CONNECTION POOL FOR THIS APPLICATION
config = configparser.ConfigParser()
CONFIG_ABSOLUTE_PATH = os.getcwd() + os.sep + 'config.ini'
config.read_file(open(CONFIG_ABSOLUTE_PATH))
postgres_url = config.get('POSTGRES', 'URL')
postgres_port = config.get('POSTGRES', 'PORT')
postgres_user = config.get('POSTGRES', 'USER')
postgres_pwd = config.get('POSTGRES', 'PW')
postgres_db = config.get('POSTGRES', 'DB')
application.app.config['postgreSQL_pool'] = psycopg2.pool.ThreadedConnectionPool(1, 20,
                                            user = postgres_user,
                                            password = postgres_pwd,
                                            host = postgres_url,
                                            port = postgres_port,
                                            database = postgres_db)
@application.app.before_request
def before_request():
    g.db = application.app.config['postgreSQL_pool'].getconn()

@application.app.teardown_appcontext
def close_conn(e):
    print('CLOSING CONN')
    db = g.pop('db', None)
    if db is not None:
        application.config['postgreSQL_pool'].putconn(db)


if __name__ == '__main__':
    application.run(port=8080)