Adding updated database configuration functions

src/app.py

@@ -4,28 +4,61 @@ from flask import Flask
 from models import db
 
 
-def database_uri() -> str:
+def database_uri() -> sqlalchemy.engine.url.URL:
     """
     A function to build the database connection string, using environment
     variable settings.
     """
+
+    # If the connection string has been given, use it.
+    url = os.environ.get("DB_CONNECTION_STRING", default="")
+    if len(url) != 0:
+        return url
+
+    # Create a new DB connection string from components.
     url = sqlalchemy.engine.url.URL.create(
-        drivername = "mariadb+mariadbconnector",
+        drivername = os.environ.get("DB_DRIVER", default="mariadb+mariadbconnector"),
         username = os.environ.get("DB_USER", default="none"),
         password = os.environ.get("DB_PASSWORD", default="none"),
         host = os.environ.get("DB_SERVER", default="127.0.0.1"),
         port = os.environ.get("DB_PORT", default="3306"),
         database = os.environ.get("DB_NAME", default="mydb"))
-    return str(url)
+
+    return url
+
+
+def database_connection_args() -> dict:
+    """
+    A function to build the connection arguments, which are associated 
+    with an SSL connection.
+    """
+    connection_args = {}
+
+    # Check for a SSL certificate.
+    ssl_cert_file = os.environ.get("DB_SSL_CERT", default=None)
+    if ssl_cert_file is not None:
+        connection_args.update({
+            "ssl_ca": ssl_cert_file
+        })
+
+    # Check if SSL should be enabled.
+    ssl_str = os.environ.get("DB_SSL", default=None)
+    if ssl_str is not None:
+        if ssl_str.strip().lower() == "true":
+            connection_args.update({
+                "ssl": "1"
+            })
+    
+    return connection_args
 
 
 def create_app(test_config:dict = {}):
+    """
+    A factory function to create a Flask app.
+    """
     app = Flask(__name__)
     app.config['SQLALCHEMY_DATABASE_URI'] = database_uri()
-    connection_args = {}
-    ssl_cert = os.environ.get("DB_SSL_CERT", default=None)
-    if ssl_cert is not None:
-        connection_args["ssl_ca"] = ssl_cert
+    connection_args = database_connection_args()
     if len(connection_args) > 0:
         app.config['SQLALCHEMY_ENGINE_OPTIONS'] = {"connect_args": connection_args}
     app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
@@ -40,6 +73,9 @@ def create_app(test_config:dict = {}):
 
 
 if __name__ == '__main__':
+    """
+    A test program to create one running Flask app.
+    """
     app = create_app()
     svc_host = os.environ.get("SVC_HOST", default=None)
     app.run(debug=True, host=svc_host)