Get server url and port from Tornado Web Framework

Question

I'm using Tornado Web Framework to build a websocket server and I need to connect via WebSocket from javascript. How can I get the server url and port from tornado templates?

I'm thinking in something like this:

<script>
var _url = "{{ (server_url) }}";
var _port = "{{ (server_port) }}";

var ws = new WebSocket("ws://" + _url + ":" + _port + "/socket");
</script>

Answer 1

I think you have to define it as context variables. Tornado doesn't provide this information to templates automatically.

It is a good idea to use tornado.options to set this variables. And then, pass them to your template.

Simplified contents of app.py:

from tornado.options import options, define

define("host", default="localhost", help="app host", type=str)
define("port", default=3000, help="app port", type=int)


class WebsocketHandler(tornado.web.RequestHandler):

    def get(self):
        self.render(
            "index_websocket.html",
            server_url=options.host,
            server_port=options.port
        )


options.parse_command_line()  # don't forget to parse command line
app = tornado.web.Application(...)
app.listen(options.port)
tornado.ioloop.IOLoop.instance().start()

In that case, you can run you application and provide defined settings:

python app.py --host=yourserveraddres.com  --port=3000