chore: proper current_app.config proxy usage (#34345)

Co-authored-by: Claude <noreply@anthropic.com>

superset/initialization/__init__.py

@@ -23,6 +23,7 @@ import sys
 from typing import Any, Callable, TYPE_CHECKING
 
 import wtforms_json
+from colorama import Fore, Style
 from deprecation import deprecated
 from flask import abort, Flask, redirect, request, session, url_for
 from flask_appbuilder import expose, IndexView
@@ -201,6 +202,12 @@ class SupersetAppInitializer:  # pylint: disable=too-many-public-methods
         from superset.views.users_list import UsersListView
 
         set_app_error_handlers(self.superset_app)
+        self.register_request_handlers()
+
+        # Register health blueprint
+        from superset.views.health import health_blueprint
+
+        self.superset_app.register_blueprint(health_blueprint)
 
         #
         # Setup API views
@@ -552,6 +559,54 @@ class SupersetAppInitializer:  # pylint: disable=too-many-public-methods
         if self.config["SESSION_SERVER_SIDE"]:
             Session(self.superset_app)
 
+    def register_request_handlers(self) -> None:
+        """Register app-level request handlers"""
+        from flask import Response
+
+        @self.superset_app.after_request
+        def apply_http_headers(response: Response) -> Response:
+            """Applies the configuration's http headers to all responses"""
+            # HTTP_HEADERS is deprecated, this provides backwards compatibility
+            response.headers.extend(
+                {
+                    **self.superset_app.config["OVERRIDE_HTTP_HEADERS"],
+                    **self.superset_app.config["HTTP_HEADERS"],
+                }
+            )
+
+            for k, v in self.superset_app.config["DEFAULT_HTTP_HEADERS"].items():
+                if k not in response.headers:
+                    response.headers[k] = v
+            return response
+
+        @self.superset_app.context_processor
+        def get_common_bootstrap_data() -> dict[str, Any]:
+            # Import here to avoid circular imports
+            from superset.utils import json
+            from superset.views.base import common_bootstrap_payload
+
+            def serialize_bootstrap_data() -> str:
+                return json.dumps(
+                    {"common": common_bootstrap_payload()},
+                    default=json.pessimistic_json_iso_dttm_ser,
+                )
+
+            return {"bootstrap_data": serialize_bootstrap_data}
+
+    def check_and_warn_database_connection(self) -> None:
+        """Check database connection and warn if unavailable"""
+        try:
+            with self.superset_app.app_context():
+                # Simple connection test
+                db.engine.execute("SELECT 1")
+        except Exception:
+            db_uri = self.config.get("SQLALCHEMY_DATABASE_URI", "")
+            safe_uri = make_url_safe(db_uri) if db_uri else "Not configured"
+            print(
+                f"{Fore.RED}ERROR: Cannot connect to database {safe_uri}\n"
+                f"NOTE: Most CLI commands require a database{Style.RESET_ALL}"
+            )
+
     def init_app(self) -> None:
         """
         Main entry point which will delegate to other methods in
@@ -567,6 +622,10 @@ class SupersetAppInitializer:  # pylint: disable=too-many-public-methods
         self.configure_feature_flags()
         self.configure_db_encrypt()
         self.setup_db()
+
+        # Check database connection and warn if unavailable
+        self.check_and_warn_database_connection()
+
         self.configure_celery()
         self.enable_profiling()
         self.setup_event_logger()
@@ -599,7 +658,7 @@ class SupersetAppInitializer:  # pylint: disable=too-many-public-methods
                 set_isolation_level_to = "READ COMMITTED"
 
         if set_isolation_level_to:
-            logger.info(
+            logger.debug(
                 "Setting database isolation level to %s",
                 set_isolation_level_to,
             )
@@ -777,6 +836,7 @@ class SupersetAppInitializer:  # pylint: disable=too-many-public-methods
             async_query_manager_factory.init_app(self.superset_app)
 
     def register_blueprints(self) -> None:
+        # Register custom blueprints from config
         for bp in self.config["BLUEPRINTS"]:
             try:
                 logger.info("Registering blueprint: %s", bp.name)