It is essential for every Python application to have an initial point, also known as the primary file, that executes as soon as the application runs. In this file, you will develop code that displays the authenticated users’ current server time. The custom MySQL and Redis modules developed earlier are used in this file to authenticate users.

To create the file, follow the instructions below:

1. Open a new file named index.py using nano index.py command.
2. Enter the following details in the index.py file:

~/project/index.py

    from encodings import utf_8

    import base64

    from hashlib import md5

    import json

    import datetime
    import http.server

    from http import HTTPStatus

    import socketserver
    import mysql_db

    import redis_db
    class HttpHandler(http.server.SimpleHTTPRequestHandler):
        def do_GET(self):
            self.send_response(HTTPStatus.OK)

            self.send_header('Content-type', 'application/json')

            self.end_headers()
            authHeader = self.headers.get('Authorization').split(' ');

            auth_user, auth_password = base64.b64decode(authHeader[1]).decode('utf8').split(':')
            mysql_server = mysql_db.MysqlDb()

            redis_server = redis_db.RedisDb()
            redis_client = redis_server.db_con()
            now = datetime.datetime.now()

            current_time = now.strftime("%Y-%m-%d %H:%M:%S")
            resp = {}
            if redis_client.exists(auth_user):
                if md5(auth_password.encode('utf8')).hexdigest() != redis_client.get(auth_user).decode('utf8'):

                    resp = {"error": "Invalid username/password."}

                else:

                    resp = {"time": current_time, "authorized by": "Redis server"}

            else:
                mysql_resp = mysql_server.query(auth_user, auth_password)
                if mysql_resp == False:

                    resp = {"error": "Invalid username/password."}

                else:

                    resp = {"time": current_time, "authorized by": "MySQL server"}

                    redis_client.set(auth_user, mysql_resp)
            self.wfile.write(bytes(json.dumps(resp, indent = 2) + "\r\n", "utf8"))
    httpd = socketserver.TCPServer(('', 8080), HttpHandler)

    print("Web server is running on port 8080...")
    try:

        httpd.serve_forever()

    except KeyboardInterrupt:

        httpd.server_close()

        print("Web server has stopped runing.")

The import section in the index.py file adds various modules, including utf_8, base64, md5, and json, which are used to encode and format text, and http.server, HTTPStatus, and socketserver that are web server modules.

The datetime module is used to obtain the system’s date and time, while mysql_db and redis_db are custom modules that were created earlier to access the MySQL and Redis servers.

The HttpHandler class is a handler class for the HTTP server, and under the class, the do_GET function serves the HTTP GET requests and displays the system’s date/time for authenticated users.

The Python script runs the if…else… logic to verify whether the user’s details exist in the Redis server. If the user details exist and the Redis stored password doesn’t match the user’s submitted password, the application returns the {“error”: “Invalid username/password.”} error.

If the user details do not exist in the Redis server, the application queries the MySQL database server using the mysql_resp = mysql_server.query(auth_user, auth_password) statement. In case the user’s supplied password doesn’t match the database stored value, the application returns the {“error”: “Invalid username/password.”} error. Otherwise, the application caches the user’s details in the Redis server using the redis_client.set(auth_user, mysql_resp) statement.

In all cases where the user’s credentials match the Redis/MySQL details, the application displays the system’s current date/time using the {“time”: current_time, …} statement. The authorized by entry in the output allows you to see the database server that authenticates the users in the application.

You have now set up the main file for the application. In the next step, you’ll test the application.