Airflow 3 Plugins

Airflow 3 plugins let you embed FastAPI apps, React UIs, middleware, macros, operator buttons, and custom timetables directly into the Airflow process. No sidecar, no extra server.

CRITICAL: Plugin components (fastapi_apps, react_apps, external_views) require Airflow 3.1+. NEVER import flask, flask_appbuilder, or use appbuilder_views / flask_blueprints — these are Airflow 2 patterns and will not work in Airflow 3. If existing code uses them, rewrite the entire registration block using FastAPI.

Security: FastAPI plugin endpoints are not automatically protected by Airflow auth. If your endpoints need to be private, implement authentication explicitly using FastAPI's security utilities.

Restart required: Changes to Python plugin files require restarting the API server. Static file changes (HTML, JS, CSS) are picked up immediately. Set AIRFLOW__CORE__LAZY_LOAD_PLUGINS=False during development to load plugins at startup rather than lazily.

Relative paths always: In external_views, href must have no leading slash. In HTML and JavaScript, use relative paths for all assets and fetch() calls. Absolute paths break behind reverse proxies.

Before writing any code, verify

1. Am I using fastapi_apps / FastAPI — not appbuilder_views / Flask?
2. Are all HTML/JS asset paths and fetch() calls relative (no leading slash)?
3. Are all synchronous SDK or SQLAlchemy calls wrapped in asyncio.to_thread()?
4. Do the static/ and assets/ directories exist before the FastAPI app mounts them?
5. If the endpoint must be private, did I add explicit FastAPI authentication?