tornado.wsgi
— Interoperability with other Python frameworks and servers¶
WSGI support for the Tornado web framework.
WSGI is the Python standard for web servers, and allows for interoperability between Tornado and other Python web frameworks and servers.
This module provides WSGI support via the WSGIContainer
class, which
makes it possible to run applications using other WSGI frameworks on
the Tornado HTTP server. The reverse is not supported; the Tornado
Application
and RequestHandler
classes are designed for use with
the Tornado HTTPServer
and cannot be used in a generic WSGI
container.
- class tornado.wsgi.WSGIContainer(wsgi_application: WSGIAppType, executor: Optional[Executor] = None)[source]¶
Makes a WSGI-compatible application runnable on Tornado’s HTTP server.
Warning
WSGI is a synchronous interface, while Tornado’s concurrency model is based on single-threaded asynchronous execution. Many of Tornado’s distinguishing features are not available in WSGI mode, including efficient long-polling and websockets. The primary purpose of
WSGIContainer
is to support both WSGI applications and native TornadoRequestHandlers
in a single process. WSGI-only applications are likely to be better off with a dedicated WSGI server such asgunicorn
oruwsgi
.Wrap a WSGI application in a
WSGIContainer
to make it implement the TornadoHTTPServer
request_callback
interface. TheWSGIContainer
object can then be passed to classes from thetornado.routing
module,tornado.web.FallbackHandler
, or toHTTPServer
directly.This class is intended to let other frameworks (Django, Flask, etc) run on the Tornado HTTP server and I/O loop.
Realistic usage will be more complicated, but the simplest possible example uses a hand-written WSGI application with
HTTPServer
:def simple_app(environ, start_response): status = "200 OK" response_headers = [("Content-type", "text/plain")] start_response(status, response_headers) return [b"Hello world!\n"] async def main(): container = tornado.wsgi.WSGIContainer(simple_app) http_server = tornado.httpserver.HTTPServer(container) http_server.listen(8888) await asyncio.Event().wait() asyncio.run(main())
The recommended pattern is to use the
tornado.routing
module to set up routing rules between your WSGI application and, typically, atornado.web.Application
. Alternatively,tornado.web.Application
can be used as the top-level router andtornado.web.FallbackHandler
can embed aWSGIContainer
within it.If the
executor
argument is provided, the WSGI application will be executed on that executor. This must be an instance ofconcurrent.futures.Executor
, typically aThreadPoolExecutor
(ProcessPoolExecutor
is not supported). If noexecutor
is given, the application will run on the event loop thread in Tornado 6.3; this will change to use an internal thread pool by default in Tornado 7.0.Warning
By default, the WSGI application is executed on the event loop’s thread. This limits the server to one request at a time (per process), making it less scalable than most other WSGI servers. It is therefore highly recommended that you pass a
ThreadPoolExecutor
when constructing theWSGIContainer
, after verifying that your application is thread-safe. The default will change to use aThreadPoolExecutor
in Tornado 7.0.New in version 6.3: The
executor
parameter.Deprecated since version 6.3: The default behavior of running the WSGI application on the event loop thread is deprecated and will change in Tornado 7.0 to use a thread pool by default.
- environ(request: HTTPServerRequest) Dict[str, Any] [source]¶
Converts a
tornado.httputil.HTTPServerRequest
to a WSGI environment.Changed in version 6.3: No longer a static method.