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tornado.httpserver — Non-blocking HTTP server

A non-blocking, single-threaded HTTP server.

Typical applications have little direct interaction with the HTTPServer class except to start a server at the beginning of the process (and even that is often done indirectly via tornado.web.Application.listen).

Changed in version 4.0: The HTTPRequest class that used to live in this module has been moved to tornado.httputil.HTTPServerRequest. The old name remains as an alias.

HTTP Server

class tornado.httpserver.HTTPServer(*args, **kwargs)[source]

A non-blocking, single-threaded HTTP server.

A server is defined by a subclass of HTTPServerConnectionDelegate, or, for backwards compatibility, a callback that takes an HTTPServerRequest as an argument. The delegate is usually a tornado.web.Application.

HTTPServer supports keep-alive connections by default (automatically for HTTP/1.1, or for HTTP/1.0 when the client requests Connection: keep-alive).

If xheaders is True, we support the X-Real-Ip/X-Forwarded-For and X-Scheme/X-Forwarded-Proto headers, which override the remote IP and URI scheme/protocol for all requests. These headers are useful when running Tornado behind a reverse proxy or load balancer. The protocol argument can also be set to https if Tornado is run behind an SSL-decoding proxy that does not set one of the supported xheaders.

By default, when parsing the X-Forwarded-For header, Tornado will select the last (i.e., the closest) address on the list of hosts as the remote host IP address. To select the next server in the chain, a list of trusted downstream hosts may be passed as the trusted_downstream argument. These hosts will be skipped when parsing the X-Forwarded-For header.

To make this server serve SSL traffic, send the ssl_options keyword argument with an ssl.SSLContext object. For compatibility with older versions of Python ssl_options may also be a dictionary of keyword arguments for the ssl.wrap_socket method.:

ssl_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
ssl_ctx.load_cert_chain(os.path.join(data_dir, "mydomain.crt"),
                        os.path.join(data_dir, "mydomain.key"))
HTTPServer(application, ssl_options=ssl_ctx)

HTTPServer initialization follows one of three patterns (the initialization methods are defined on tornado.tcpserver.TCPServer):

  1. listen: simple single-process:

    server = HTTPServer(app)

    In many cases, tornado.web.Application.listen can be used to avoid the need to explicitly create the HTTPServer.

  2. bind/start: simple multi-process:

    server = HTTPServer(app)
    server.start(0)  # Forks multiple sub-processes

    When using this interface, an IOLoop must not be passed to the HTTPServer constructor. start will always start the server on the default singleton IOLoop.

  3. add_sockets: advanced multi-process:

    sockets = tornado.netutil.bind_sockets(8888)
    server = HTTPServer(app)

    The add_sockets interface is more complicated, but it can be used with tornado.process.fork_processes to give you more flexibility in when the fork happens. add_sockets can also be used in single-process servers if you want to create your listening sockets in some way other than tornado.netutil.bind_sockets.

Changed in version 4.0: Added decompress_request, chunk_size, max_header_size, idle_connection_timeout, body_timeout, max_body_size arguments. Added support for HTTPServerConnectionDelegate instances as request_callback.

Changed in version 4.1: HTTPServerConnectionDelegate.start_request is now called with two arguments (server_conn, request_conn) (in accordance with the documentation) instead of one (request_conn).

Changed in version 4.2: HTTPServer is now a subclass of tornado.util.Configurable.

Changed in version 4.5: Added the trusted_downstream argument.

Changed in version 5.0: The io_loop argument has been removed.