Add base code for REST API using Flask

tofu_api/app.py

@@ -1,10 +1,32 @@
-def app(environ, start_response):
-    """Simplest possible application object"""
-    data = b'Hello, wooorld!\n'
-    status = '200 OK'
-    response_headers = [
-        ('Content-type', 'text/plain'),
-        ('Content-Length', str(len(data)))
-    ]
-    start_response(status, response_headers)
-    return iter([data])
+import os
+
+import yaml
+from flask import Flask
+
+from tofu_api.api import TofuApiBlueprint
+from tofu_api.config import DefaultConfig
+
+
+def create_app() -> Flask:
+    """
+    App factory, returns a Flask app object.
+    """
+    # Set instance path to the project root directory
+    project_root_dir = os.path.abspath('.')
+
+    # Create and configure the app
+    app = Flask(
+        'tofu_api',
+        instance_path=project_root_dir,
+        instance_relative_config=True,
+    )
+    app.config.from_object(DefaultConfig)
+
+    # Load app configuration from YAML file
+    app.config.from_file(os.getenv('FLASK_CONFIG_FILE', default='config.yml'), load=yaml.safe_load)
+
+    # Register blueprints
+    app.register_blueprint(TofuApiBlueprint())
+
+    # Return WSGI app
+    return app