Flask App Initialization

deployless automatically uses your create_app() factory to initialize each Lambda — no extra configuration needed.

Zero-config: app factory auto-detection

If your project has a create_app() function in app/__init__.py, the generated bootstrap calls it directly:

app/__init__.py

def create_app() -> Flask:
    app = Flask(__name__)
    CORS(app, origins=settings.CORS_ORIGINS)
    register_error_handlers(app)
    app.register_blueprint(todo_bp)
    return app

The generated bootstrap:

.dist/TodoFunction/bootstrap.py (auto-generated)

try:
    from app import create_app as _deployless_factory
    flask_app = _deployless_factory()  # CORS, error handlers, etc. all applied
    del _deployless_factory
except (ImportError, AttributeError) as _e:
    # Fallback: manual bootstrap
    ...

For multi-feature projects, deployless generates minimal stubs for other features so create_app() can import all blueprints without errors:

.dist/TodoFunction/
  app/
    __init__.py              ← real (with create_app)
    features/
      todo/                  ← real code
      auth/routes.py         ← stub (empty Blueprint, ~5 lines)
      user/routes.py         ← stub (empty Blueprint, ~5 lines)
    shared/

Fallback: manual bootstrap

If create_app() is not found or fails to import, deployless falls back to manual bootstrap, registering blueprints directly. In this case, cors: and init_app: from deployless.yaml are used.

A warning is printed to stderr:

[deployless] create_app() unavailable (...). Using manual bootstrap.

init_app (legacy / override)

init_app in deployless.yaml is the explicit alternative for projects without an app factory. It is only applied in the fallback path.

deployless.yaml

init_app:
  - app.shared.errors.register_error_handlers
  - app.shared.middleware.register_middleware

Each entry is a dotted module.function path. deployless imports and calls function(flask_app):

from app.shared.errors import register_error_handlers
register_error_handlers(flask_app)

Validation

Code	Rule
E31	Each init_app entry must be a string in module.function format