Validate templates at startup.

Author: Johnny Bouder

app/main.py

@@ -35,29 +35,32 @@
 Base.metadata.create_all(bind=engine)
 logger.info("Database tables created")
 
-# Load and cache the landing page template at startup
-_landing_page_template: str | None = None
-try:
+# Cache for landing page template
+_landing_page_template: str = ""
+
+
+@app.on_event("startup")
+async def startup_event():
+    """Validate application configuration and load required resources."""
+    global _landing_page_template
+
+    # Load landing page template - fail fast if not available
     html_path = Path(__file__).parent / "templates" / "index.html"
-    _landing_page_template = html_path.read_text()
-    logger.info("Landing page template loaded successfully")
-except Exception as e:
-    logger.error("Failed to load landing page template from %s: %s", html_path, e)
+    try:
+        _landing_page_template = html_path.read_text()
+        logger.info("Landing page template loaded successfully from %s", html_path)
+    except FileNotFoundError as exc:
+        logger.critical("Landing page template not found at %s", html_path)
+        raise RuntimeError(f"Required template file not found: {html_path}") from exc
+    except Exception as e:
+        logger.critical("Failed to load landing page template: %s", e)
+        raise RuntimeError(f"Failed to load required template: {e}") from e
 
 
 # Root endpoint with API documentation links
 @app.get("/", response_class=HTMLResponse, include_in_schema=False)
 def root():
     """Render an HTML page with links to API documentation."""
-    if _landing_page_template is None:
-        logger.error("Landing page template not available")
-        return HTMLResponse(
-            content=(
-                "Error: Unable to load the homepage template. "
-                "Please contact the administrator."
-            ),
-            status_code=500,
-        )
     return _landing_page_template