FastAPIPassthroughAuthMiddleware

Package: flyte.app.extras

FastAPI middleware that automatically sets Flyte auth metadata from request headers.

This middleware extracts authentication headers from incoming HTTP requests and sets them in the Flyte context using the auth_metadata() context manager. This eliminates the need to manually wrap endpoint handlers with auth_metadata().

The middleware is highly configurable:

• Custom header extractors can be provided
• Specific paths can be excluded from auth requirements
• Auth can be optional or required

Thread Safety: This middleware is async-safe and properly isolates auth metadata per request using Python’s contextvars. Multiple concurrent requests with different authentication will not interfere with each other.

Parameters

class FastAPIPassthroughAuthMiddleware(
    app,
    header_extractors: list[HeaderExtractor] | None,
    excluded_paths: set[str] | None,
)

Initialize the Flyte authentication middleware.

Methods

dispatch()

def dispatch(
    request: 'Request',
    call_next,
) -> 'Response'

Process each request, extracting auth headers and setting Flyte context.

Returns: The HTTP response from the handler

extract_authorization_header()

def extract_authorization_header(
    request: 'Request',
) -> tuple[str, str] | None

Extract the Authorization header from the request.

Returns: Tuple of (“authorization”, header_value) if present, None otherwise

extract_cookie_header()

def extract_cookie_header(
    request: 'Request',
) -> tuple[str, str] | None

Extract the Cookie header from the request.

Returns: Tuple of (“cookie”, header_value) if present, None otherwise

extract_custom_header()

def extract_custom_header(
    header_name: str,
) -> HeaderExtractor

Create a header extractor for a custom header name.

Example::

# Create extractor for X-API-Key header
api_key_extractor = extract_custom_header("x-api-key")

app.add_middleware(
    FastAPIAuthMiddleware,
    header_extractors=[api_key_extractor],
)

Returns

A header extractor function that extracts the specified header